AGRO- PROCESSING OF PATCHOULI (Pogostemon cablin Benth.) FOR EFFICIENT ESSENTIAL OIL
EXTRACTION
ANITHA, M.
DEPARTMENT OF AGRICULTURAL ENGINEERING
UNIVERSITY OF AGRICULTURAL SCIENCES BANGALORE
2008
ii
AGRO- PROCESSING OF PATCHOULI (Pogostemon
cablin Benth.) FOR EFFICIENT ESSENTIAL OIL EXTRACTION
ANITHA, M.
THESIS SUBMITTED TO THE
UNIVERSITY OF AGRICULTURAL SCIENCES, BANGALORE
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
AWARD OF THE DEGREE OF
MASTER OF TECHNOLOGY (AGRICULTURAL ENGINEERING)
IN
POST HARVEST PROCESS AND FOOD ENGINEERING BANGALORE
JULY, 2008
iv
Affectionately Dedicated to My Beloved Parents
& Sisters
iii
C e r t i f i c a t e
This is to certify that the thesis entitled Agro-Processing of Patchouli (Pogostemon cablin Benth.) for Efficient Essential Oil
Extraction submitted in partial fulfillment of the requirements for the
award of degree of Master of Technology (Agricultural Engineering) in
Post Harvest Process and Food Engineering to the University of
Agricultural Sciences, Bangalore, is a bona fide record of research work carried out by Ms. Anitha, M. under my guidance and supervision and that
no part of the thesis has been submitted for the award of any other degree,
diploma, associateship, fellowship or any other similar titles.
Bangalore Dr. V. PALANIMUTHU July 2008 Major Advisor
APPROVED BY:
Chairman : ______________________________
(V. PALANIMUTHU)
Members: ______________________________
1. (B. RANGANNA)
______________________________
2. (H. ESHWARAPPA)
______________________________
3. (K.B. MUNISHAMMANA)
______________________________
4. (M. HANUMANTHAPPA)
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Acknowledgment
I am extremely grateful and indebted to my chairperson Dr. V. Palanimuthu, Assistant research Engineer, PHT Scheme, UAS, Bangalore for his inspiring, untiring, valuable guidance, constructive criticism, constant encouragement and above all the love and affection offered to me during the course of my study and research. Without his constant support and guidance, preparation of this manuscript wouldn’t have been possible. I consider myself lucky to have worked under the guidance of the knowledge hungry, excellence pursuing and ever helpful personality.
My heartfelt thanks are due to Dr. B. Ranganna, Professor and Research Engineer, PHT Scheme, UAS, Bangalore, for his constant encouragement, sense of responsibility and help as a human being, advice and for his valuable suggestions during the course of my investigation.
I place to record my profound indebtedness and gratitude to Mr. R. Chandru, Associate Professor of Biochemistry, PHT Scheme, for his encouragement, valuable suggestions, sustained interest on the selected problem and the help during the course of my investigation.
I owe an intellectual debt to, Mr.H. Eshwarappa Professor and Head, Department of Agricultural Engineering, for all his help during my research and stay at UAS, Bangalore.
My heartfelt thanks are also due to Mr. Munishyamanna, Associate Professor, PHT Scheme, UAS, Bangalore, who served as one of my Members of Advisory Committee.
I thank Central Institute of Medicinal and Aromatic Plants for providing patchouli fresh herbage for drying purpose and for quality analysis of patchouli oil performed in their laboratory.
I thank to IISC,for providing Astra dryer for patchouli drying.
I take this opportunity to thank the staff of PHT scheme, Mr. Mohan, Mrs. Channamma and the workers Narayanappa and Hanumakka, workshop staff Mr. Bhaskar, Anand, , Kumar and Changappa sir, Dept of Horticulture who have helped me during my research work and also were a great company in Scheme.
My vocabulary fails to get words to convey my wholehearted thanks to my lifetime friends pex, jay, and Sum and my room mates Lacchi, Jo, Prathi, Chethu for their
vi
natured and selfless help during my research. Their constant companionship, love and moral support always give me strength in odd times.
I would also like to thank my PG friends Anupama, Jyothi, Shwetha, Ravi, Raghu, and Shivbasappa for their kind help and company during my studies.
Words sometimes fail to express when the occasion really demands it. However, with all the limitations of words, I offer my floral salutations laden with pure love that contain only my feelings towards my parents (Muniramaiah& susheela), elder sister (vanaja) younger sister (sunitha) and to my whole family members. It is my sinscere duty to acknowledge their undemanding, steadfast support and love during my entire career that stands immaculately in my memory.
I would like to express my sincere thanks to my cousins, aunty, uncle and for their constant inspiration, encouragement and blessings.
I sincerely thank all those who directly or indirectly helped me during the course of this investigation.
I’m grateful to University of Agricultural Sciences, Bangalore for providing me the opportunity and facilities to prosecute my Post-graduation Degree.
Bangalore July 2008 (Anitha.M)
Agro-Processing o f Patchouli (P(>gostemon cablin Benth.J fo r EfficientEssential o / / Extraction
A n itha M.
Thesis Abstract
A g ro -p ro c e s s in g o f p a tc h o u l i , (cv. j 0 }X 0 r e } a n im p o r ta n t a ro m a tic he rb v a lu e d for i ts e s s e n t i a l oil, w a s a t te m p te d . The d ry ing c h a ra c te r is t ic s of h e r b a g e w e re s t u d i e d u n d e r v a r io u s m e th o d s n am ely , in sh a d e , in tray d r y e r a n d in ASTRA C ro p W a s te g aseci Dryer. T he in itial d ry ing bed t h i c k n e s s w a s u n i fo r m ly m a in t a in e d a t 100 m m in all m e th o d s a n d the h e r b a g e w a s d r ie d f ro m 80% (w b) initial m o is tu re to 11-12% final m o is tu r e . U n d e r B a n g a lo re c l im a tic cond itions (21 .0-24 .4°C ; 40 -81% RH), p a t c h o u l i r e q u i r e d 5 4 h o f d ry in g tim e in s h a d e w hile in ASTRA d ry e r , i t w a s j u s t 14 h . In c o n v e c t i0 n a i tray d ryer (electrical), th e d iy ing t im e a t 3 0 , 4 0 , 5 0 , 6 0 a n d 70°C w a s 13, 12, 11, 7 a n d 6 h, respectively.
C le v e n g e r ’s E s s e n t i a l Oil D is til la tion U nit w as u s e d to e s t im a te the e s s e n t i a l oil y ie ld fro m d r ie d p a tc h o u l i an d the oil q u a li ty w as analyzed u s i n g G a s C h r o m a to g r a p h . T h e m e a n e ssen tia l oil y ie lds w ere 2 .41 , 2 .24 a n d 2 .2 5 - 2 .4 0 % re s p e c t iv e ly in s a m p le s dried in sh ad e , ASTRA d ry e r an d t r a y d ry e r . T h e r e w a s a c o n s id e r a b le varia tion in th e q ua li ty of ex trac ted p a tc h o u l i e s s e n t i a l oil in t e r m s p a tc h o u l i alcohol, a -g u a ien e , ct-bulnesene a n d (3 -p a tc h o u le n e c o n t e n t s , from h e rb ag e dried u n d e r different m e th o d s . P a tc h o u l i a lc o h o l c o n t e n t w as 64 .6 5 , 4 2 .2 7 a n d 5 7 .15 -66 .26% in th e d is t i l le d o i ls f ro m h e r b a g e dried in sh ad e , ASTRA d ry e r a n d tray d ry e r , re sp ec t iv e ly . T h e a - g u a ie n e a n d a -b u ln e se n e c o n te n t s were h igher in e s s e n t i a l o i ls d is t i l le d fro m h e rb ag e dried in ASTRA dryer, p- p a t c h o u l e n e c o n t e n t w a s h ig h e r in th e oil distilled from h e rb ag e dried a t 70°C in t r a y d iy e r .
E s s e n t i a l oil y ie ld a n d i ts q u a li ty by s te a m distilla tion techn ique w e re s tu d i e d in a P ilo t S c a le S te a m Distillation U nit a t d ifferent pack ing b e d d e n s i t i e s a n d d is t i l la t io n p e rio d s u s in g sh a d e d r ied patchouli h e r b a g e . F o r d i f f e r e n t p a c k in g d e n s i t ie s , th e p a tch o u l i e ssen tia l oil yields w ere : a t 4 k g / 0 . 5 m 3 - 2 .7 8 , 3 .0 6 , 3 .2 6 a n d 3 .42% ; a t 5 k g /0 .5 m 3 - 2 .46 , 2 .7 4 , 2 .9 5 a n d 3 .1 0 % ; a n d a t 6 k g /0 .5 m 3 - 2 .25 , 2 .54 , 2 .7 9 a n d 2 .97% re sp ec t iv e ly fo r 3, 4 , 5 a n d 6 h d is t i l la t ion . F rom s te a m distilled e ssen tia l o ils , p a t c h o u l i a lc o h o l w a s 3 4 .7 4 , 34 .92 a n d 27 .78% ; a -b u ln e se n e c o n t e n t w a s 2 0 .0 4 , 1 9 .7 5 a n d 19 .38% ; a -g u a ien e c o n te n t w as 12.75, 12 .71 a n d 1 9 .3 8 % ; a n d p - p a tc h o u le n e c o n te n t w as 0 .0 1 8 7 , 0 .0 1 6 5 a n d 0 .0 0 0 % re s p e c t iv e ly a t b e d d e n s i t i e s 4, 5 a n d 6 k g /0 .5 m 3.
C o s t e c o n o m ic a n a ly s i s o f p a tch o u l i e s se n t ia l oil d is tilla tion u s in g P ilo t S c a le S t e a m D is t i l la t io n U n it in d ica ted th a t the ex trac tion is viable w i th C o s t : B e n e f i t R a t io o f 1 :1 .26 .
D a te : 0 1 / 1 0 / 2 0 0 8 P lace : B a n g a lo re
(V. PALANIMUTHU)M ajor Advisor
Contents
Sl. No.
TITLE
Page No.
I
INTRODUCTION
1-5
II REVIEW OF LITERATURE
6-21
III MATERIALS AND METHODS
22-41
IV RESULTS
42-64
V DISCUSSION
65-72
VI SUMMARY
73-76
VII REFERENCES
77-85
APPENDICES
86-89
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List of Tables
Table No. TITLE Page
No.
4.1 Effect of drying of patchouli herbage on the refractive index of extracted essential oil 56
4.2 The influence of packing density and distillation time on patchouli essential oil quality 58
4.3 Effect of bed packing density and distillation
time on refractive index of patchouli essential oil 60
4.4 Effect of type of distillation on the yield and quality of essential oil 61
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List of Figures Fig. No. TITLE
Page No.
4.1 Drying characteristics of patchouli herbage in tray dryer 43
4.2 Drying behaviour of patchouli herbage under shade 43
4.3 Drying behaviour of patchouli herbage in ASTRA Model Waste Based Crop Dryer 44
4.4 Drying air temperature variation at different levels inside ASTRA Model Dryer during Patchouli drying 44
4.5 Essential oil recovery from Patchouli herbage dried under Shade, in tray dryer at different drying temperature and in ASTRA Dryer
47
4.6 Gas chromatographic profile of patchouli oil 48
4.7 Effect of drying of patchouli herbage on patchouli alcohol content of extracted patchouli oil 49
4.8 Effect of drying of patchouli herbage on β- patchoulene content of extracted patchouli oil 49
4.9 Effect of drying of patchouli herbage on -Guaiene content of extracted patchouli oil 51
4.10 Effect of drying of patchouli herbage on -Bulnesene content of extracted patchouli oil 51
4.11 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 4 kg/0.5m³ 53
4.12 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 5 kg/0.5m³ 53
4.13 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 6 kg/0.5m³ 54
4.14 Essential oil recovery from shade dried patchouli herbage at various distillation time intervals (packing bed density of 4 kg/0.5m³)
54
4.15 Variation in patchouli oil quality at different distillation time intervals for packing bed density 4 kg/0.5m³ 55
4.16 Variation in patchouli oil quality at different distillation time intervals for packing bed density 5 kg/0.5m³ 55
4.17 Variation in patchouli oil quality at different distillation time intervals for packing bed density 6 kg/0.5m³ 63
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List of Plates
Plate No.
TITLE
Page No.
3.1 A view of shade drying of patchouli 24
3.2 Convective tray dryer 24
3.3 ASTRA dryer 27
3.4 Tray of ASTRA Dryer 27
3.5 Fuel Briquettes 29
3.6 Dial Thermometer 29
3.7 Moisture Determination Apparatus 31
3.8 Clevenger’s Essential Oil Distillation Unit 33
3.9 Pilot Scale Steam Distillation Unit 36
3.10 Essential oil separating funnel 36
3.11
Patchouli essential oil 36
3.12 Gas chromatograph 40
3.13 Polarimeter 40
3.14 Refractometer 40
INTRODUCTION
1
I INTRODUCTION
Patchouli, a small bushy perennial herb with fragrant leaves, is an
important aromatic plant. It is botanically known as Pogostemon cablin
Benth. and belongs to the family Labiatae. The patchouli plant was first
described by botanists Pelletier-sautelet in Philippines in 1845 and was
named Pogostemon Patchouli. It is believed to be a native of the
Philippines. It grows wild in Malaysia, Indonesia and Singapore. It is
often confused with Pogostemon heyneaxhus Benth., which is indigenous
to India and is grown in gardens, but has no commercial importance.
Patchouli oil is a key constituent in exotic perfumes to which it gives a
rich, spicy fragrance. It can also be used as a perfume in its own right. It
has also good fixative properties, especially in soap perfumes (Farooqui
and Sreeramu, 2001).
Patchouli was introduced to India during the year 1941 in Madhya
Pradesh, Tamilnadu, Kerela and Karnataka. Experiments have revealed
that good quality patchouli oil can be produced from patchouli grown
under Bangalore weather conditions (Sarwar et al., 1982).
Patchouli is grown for its essential oil which is found mainly in the
leaves and a small quantity of oil is also present in the tender parts of
the stem. The dry leaves of patchouli on steam distillation yield an
essential oil called ‘oil of patchouli’. The leaves harvested and dried in
shade have an oil content in the range of 2.5-3.5%.
Most of the patchouli oil of the world is produced by Indonesia,
Malaysia and Singapore. Indonesia supplies most of the world’s
requirement of around 1500 tonnes per year. India produces about 1
tonne of patchouli oil (Rao, 2004) and the demand borders around 220
2
tonnes annually (Vijyakumar, 2004). Commercial cultivation of the crop
in India was first attempted by Tata Oil Mills in 1942 (Anup Kumar et al.,
1986). After the initial stray attempts to grow the crop, its systematic
cultivation started in 1962 by CIMAP (Anup Kumar et al., 1986).
Currently, India producing a very meager quantity of patchouli oil and
thus is annually importing about 20 tonnes of pure patchouli oil and 100
tonnes of formulated oils.
The first harvest of patchouli crop is obtained after 5-6 months of
transplanting. It is harvested when the foliage becomes pale green to
light brown and when the stand emits the characteristic patchouli odour
that can be smelt by a passer-by, especially in the morning hours.
Subsequent harvests can be done after every 3-4 months interval. The
crop can be maintained for three years. The harvested material is
generally dried under shade in thin layers and for proper drying, the
material has to be periodically turned. Drying normally takes about three
days (Farooqui and Sreeramu, 2001) and the shade dried material is
stored for ageing even for months before distillation to improve the
characteristic aroma. The duration of distillation is about 6-8 hours for
complete recovery of oil (Anon., 2004a).
The patchouli crop yields about 1750-2500 kg dried leaves
(includes twigs also), 45-65 kg of patchouli oil and a net profit of Rs
40,000-60,000 per hectare per annum can be realized (Anon., 2004a).
Only matured patchouli leaves are harvested, shade dried and steam
distilled (Jain, 1978) and an average essential oil yield of 2.5% may be
considered satisfactory in commercial distillation (Farooqui et al., 2001).
Dry patchouli leaves are used for scenting wardrobes. The leaves
and tops are added in bath for their anti rheumatic action. In Chinese
medicine, decoction from the leaves is used with other drugs to treat
3
nausea, vomiting, diarrhea, cold and headaches (Leung, 1980). A related
species P. heyneanus is reported to contain principles possessing
anticancer activity (Purushothaman et al., 1985).
The chemical constituents that are most odour-intensive in the
patchouli oil are patchouli alcohol and nor patchoulenol. Other
components include Alpha Bulnesene, Alpha, Beta and Delta
Patchoulene, Alpha and Delta Guaiene, Beta Elemene and Seychellene
(Shankaranrayan, 2002).
In aromatherapy, patchouli is often used as a relaxant. It can ease
and diminish anxiety and depression. In high dose, it can stimulate and
in lower dose, it is a sedative. It is used to sharpen intelligence and
improve concentration (Shankaranrayan, 2002).
Patchouli oil is thick, viscous, sticky and very slow to volatilize.
High quality oils possess an elusive, wine-like, floral, sweet top-note. This
top-note commands more of a presence as the oil ages (approximately
one year from distillation). The body note is incredibly rich, intensely
sweet, woody, balsamic and earthy (Anon., 2005a). It is found that 92%
of the patchouli oil consists of compounds which have very little
influence upon its odour. Sesquiterpenes constitute 40 to 45% of the oil,
out of which patchouli camphor or patchouli alcohol or patchoulol
represents 35 to 40% of the oil. Patchouli alcohol is also odourless.
However, it is found that one or more satellite compounds of patchoulol
may be responsible for the characteristics odour. In addition, a
crystalline fraction of norsesquiterpenic alcohol called nor patchoulenol
is isolated which is found to be the true odour carrier of the patchouli oil
(Sarwar et al., 1982).
4
Patchouli oil is used so extensively that is very difficult to specify
its field of application. It is one of the most important essential oils in
perfume industry. It blends well with other essential oils such as, vetiver,
sandalwood, geranium, lavender, caedarwood derivatives and clove oil.
The oil is extensively used as a flavor ingredient in major food products
including alcoholic and non alcoholic beverages, frozen dry desserts,
candy, baked goods, gelatin, and meat and meat products. Blended with
sandalwood oil, it gives one of the finest attars, widely used in soaps,
cosmetics, tobacco and incense sticks. Hence, it is regarded as the best
fixative for heavy perfumes which imparts strength, character, alluring
notes and lasting qualities. There is no synthetic chemical to replace the
oil of patchouli, which further enhances its value and unique position in
the perfumery market. There is a great demand for it in soaps, scents,
body lotions, detergents, tobacco and incense manufacturing factories.
The oil of patchouli is used also as an ingredient in insect repellent
preparations and is said to have anti-bacterial properties as well
(Farooqui and Sreeramu, 2001).
Only few works are reported on the processing aspects of patchouli
though considerable progress has been made in the cultivation front. It is
reported that in the commercial extraction facilities, the oil yield is only
about 1-2.5 % or even less, either due to poor distillation technique/
equipment or due to improper handing of raw material before distillation
(Anon., 2004b).
Pallavi et al. (2006) studied the drying characteristics of patchouli
herbage in a convectional tray dryer and reported that the drying
temperatures of 30-50°C did not influence the essential oil yield and the
oil yield was similar to that of shade dried sample. Tandon et al. (2002)
reported that there was no significant increase in the oil recovery rather
5
there was a loss of the oil occurring at high steam pressures during
distillation of Menthe herb.
Patchouli is a farmer friendly crop and it is not so delicate to
handle like many other aromatic plants. The leaves once dried and
properly preserved can be used for distillation leisurely. Since the
present extraction efficiency of this high valued oil is poor due to many
hurdles, the development of a good distillation equipment and proper
process technique will definitely enhance the oil extraction efficiency. The
process technique will be highly beneficial to the farming community and
it will increase their net returns considerably.
With the above points in view, the present investigation was
undertaken with the following objectives:
Objectives
1) Standardization of drying practices of patchouli for distillation.
2) Optimization of distillation parameters for maximum oil recovery from patchouli using a Pilot Scale Steam Distillation Unit.
3) Quality analysis of steam distilled patchouli essential oils.
4) Cost-economic analysis of patchouli distillation process.
REVIEW OF LITERATURE
6
II. REVIEW OF LITERATURE
Patchouli is an important aromatic crop yielding an invaluable
essential oil. The review of literature indicates that there is not much
published research work on processing aspects of this plant like initial
raw material handling, drying practices and distillation.
In the following sections of this chapter, valuable information
regarding patchouli, its drying, development/testing of a small pilot scale
distillation unit, extraction and quality analysis of patchouli essential oil
and other informations relevant to this investigation have been briefly
reviewed.
2.1 Drying Studies of Aromatic Crops
The fermentation of patchouli leaves and its effect on yields of oil
has been a matter of debate. Subba Rao and Nagesa Rao (1945) reported
that fermentation of leaves improved the oil quality.
Nirody et al. (1961) have shown that though it is said that the
fermentation helps to increase the breakdown of cells and thereby
promotes the oil yield, there is little experimental evidence, if any, to
show additional oil generation by fermentation. Improper fermentation
may cause moldy odour of the oil, while some experts believe that unless
the leaves are fermented, oil of the best odour quality cannot be
obtained.
Nair et al. (1980) studied the factors influencing the yield of
essential oils during distillation. In case of lemongrass and Palma Rosa,
7
field drying and storing of the cut crop in open air reduced the oil yield
as well as the active chemical content in the oil.
A pilot plant scale experiment conducted by Hazra et al. (1990) to
study the effect of drying mint herb in shade and direct sunlight in two
different seasons indicated that in field drying, the oil yield progressively
reduced with time. However, in shade drying, the oil yield increased up to
two days of drying, and then gradually decreased.
Deans and Svoboda (1992) conducted experiments on drying of
seven herb spices. The herbs were dried at temperatures between 40°C
and 100°C for 24 h and the dried material was then steam distilled. They
reported that the volatile compounds decreased with increase in drying
temperature and there was a significant change in oil composition of all
the seven herb spices studied. The composition of marjoram and basil
oils changed significantly, those of tarragon, sage and savery oils
changed at 50-60°C, while those of thyme and rosemary oils did not
change significantly.
Raghavan et al. (1995) subjected fresh Indian thyme to different
drying treatments. Shade drying was found to be time consuming
process (124h) during which most of the monoterpenes were lost due to
volatilization. Thymol was retained in all dried samples. Considering the
time of drying and the flavour quality of the herb, through-flow drying
(40°C, 8 h) was found to be a method of choice. However shade drying
resulted in a product with a good green colour and minimum loss of
volatile oil compared to other drying methods.
Upon subjecting Artemisia annua to six drying techniques (sun, air
dried inside or outside and forced air heat at 30, 50, 80°C) and five
durations (0, 12, 24, 36 and 48 h), artemisinin content was best retained
8
when leaves were dried under ambient conditions, compared with forced
air (Charles et al. 1995).
Chiumenti et al. (1996) studied the effect of drying temperature on
Salvia officinals and reported that as the temperature increased, the
process duration decreased from 56.8 to 13 h. The total drying energy
required for heating air increased with temperature up to 75°C and then
decreased. Essential oil composition was found to vary slightly depending
on temperature.
Drying of patchouli normally takes three days under shade,
yielding an average of 2.5% essential oil up on distillation (Farooqui et al.
2001).
Pallavi et al. (2006) studied the drying characteristics of patchouli
herbage in a conventional tray dryer and reported that the drying
temperatures of 30-50°C did not influence the essential oil yield and the
oil yield was similar to that of the shade dried sample.
Though drying is one of important the unit operations before
essential oil extraction, very little information is available in the literature
on drying studies of patchouli herbage.
2.2 Extraction of Essential Oil from Aromatic Plant
The basic criteria for essential oils conforming to EOBBD
(Essential Oils Botanically and Biochemically Defined) quality standards
are the exact botanical identification of the aromatic plant, its
geographical origin, stage of development at the time of harvest, the
distilled organ and the most important and critical factor, the process of
9
steam distillation. Each essential oil is identified by its GC-MS profile
besides other physical properties. The quality of essential oil is
established by the presence of specific biochemical constituents at
defined levels for effective human application (Manivannan and
Suvarnalatha, 1988).
Among the various production methodologies of essential oil,
distillation methods are good for grassy and leafy materials where as,
extraction is suitable for highly priced, delicate and thermally sensitive
perfumery materials like jasmine, tuberose, violet, etc.Super-critical fluid
extraction is the most recent and promising method of production of
essential oil from natural products (Singh, 1990).
During the early history of man, distilled waters of herbs were
produced and used as remedy for many illnesses. In the fourth century,
stills were constructed with a gorge weir situated at the bottom portion of
the head. The weir allowed some separation of the condensates. In the
twelfth century, the distillation still was practically of same shape as it is
now and the head gorge weir had been replaced by a worm placed in a
cold water vat in which vapors were condensed and cooled (Vacchiano,
1992).
Until year 1955, separation techniques were essentially based on
chemical composition, fractional distillation and crystallization. Complete
separation of all the components is not readily achieved since, many
terpenoids and other classes of compounds have a small range of boiling
points, even the most efficient fractionating procedures do not always
produce pure compounds. Some polymerization occurs during distillation
and resolutions are only mediocre (Singh et al. 1995).
10
2.3 Extraction Methods
A new extraction process for isolation of essential oil/extractives
from natural substances using liquid and dense carbon dioxide has been
described. Cardamom (fruits), cumin (seeds), clove (buds), ginger
(rhizomes), parsley (seeds), mace (arils), sandalwood (stems) and vetiver
(roots) are used as extraction materials in a specially designed high
pressure soxhlet apparatus for preliminary studies of liquid carbon
dioxide extraction. The essential oils/extractives obtained by this method
are found superior in quality and flavour compared with the conventional
steam distilled essential oils. The process conditions for extraction of
clove, parsley and vetiver with liquid and dense carbon dioxide studied at
different pressure and temperatures in a high pressure gas extraction are
found at sub critical state (Naik et al., 1988).
The different methods presently available for extracting aroma of
floral materials are:
a) Distillation with water or wet steam
b) Extraction with hexane, concentrate of the extract with low
temperature, removal of plant waxes by precipitation with an
odourless alcohol and removal of alcoholic solvent at low
temperature
c) Super critical carbon dioxide extraction (Geunther, 1948).
d) Liquid carbon dioxide for extraction (Naik et al. 1988).
Steam distillation of air dried leaves yield oil of patchouli. Different
methods of distillation are employed by distillers. Experienced distillers
prepare oils of special quality by varying the conditions of distillation.
Distillation is the main method used for extracting essentials oils.
Distillation is based on the principal that when plant material is placed
11
in boiling water, the essential oil in it will evaporate and rise up along
with the steam. Once the steam and oil have been condensed, the oil
separate from the water, and it can be collected. Plants are crushed to
encourage them to release their oils. The collected essential oils are
poured in to Florentine flasks for separation. Five to six tonnes of roses
are needed to obtain one kilogram of essential oil. Current methods also
involve placing the plants on a screen and steam is passed through them
(Anon., 2005b).
There are several techniques that allow the extraction of
compounds responsible for the aroma of plants. The composition of the
aromatic material obtained is strongly dependent on the method of
isolation. The techniques used at industrial scale are cold pressing,
hydro distillation, extraction with organic solvents and extraction with
compressed CO2. Both cold pressing and hydro distillation enable the
isolation of the essential oil borne in the plant; however both approaches
have their disadvantages. Hydro distillation can thermally degrade and
hydrolyse some of the oil components, which in some cases can lead to
significant distortion of the composition of oils found in the natural herb.
Cold pressing is insufficient and the oil obtained requires refining to
concentrate the oil produced (Anon., 2005c).
i) Hydro-distillation
There exits three types of hydro distillations in essential oil
industry:
1. Water distillation
2. Water and steam distillation
3. Direct steam distillation
12
All the three types are basically similar in principle of two phase
system of distillation with only difference in handling the plant material.
The term hydro-distillation was coined by Von Rechenberg, referring to
the distillation with water vapors that isolated a majority of essential oils.
(Prasad et al. 1988).
Hydro distillation is a process where botanicals are fully
submerged in water, and heated up. The steam produced that contains
the aromatic plant molecules is condensed and separated to obtain
essential oils. This is the most ancient method of distillation and the
most versatile. The risk, of course, is that the still can run dry, or be
overheated, burning the aromatics and resulting in an essential oil with a
burnt smell. Hydro distillation seems to work best for powders (i.e. spice
powder, ground wood etc) and very tough materials like roots, wood or
nuts (Anon., 2005d).
ii) Steam distillation
Steam distillation is the common method used for the extraction of
essential oils from plants. The plant material is placed in a still (very
similar to pressure cooker) where pressurized seam passes through the
plant material. The heat from the steam causes the globules of oil in the
plant to burst and the oil then evaporates. The essential oil vapour and
the steam then passes out the top of the still in to a water cooled pipe
where the vapors are condensed back to liquids. At this point the
essential oil separates from the water floats to the top (Anon., 2005e).
Although there are other techniques, steam distillation remains the
preferred process for the extraction of essential oils from plant material
from the consumer point of view. From a commercial point of view, the
ability to process large quantities of material with a technique that
13
requires relatively modest investment and skill levels is attractive (Anon.,
2005f).
Steam distillation results in two separate by products: (1) The
liquid distillate itself which contains the volatile, water soluble parts of
the plant materials is known as “hydrosol” and (2) The volatile non water
soluble material which possesses the greater of the plant constituents
and is known as the “essential oil”. Additionally, the process of
distillation inherently produces new chemical compound that would not
be found naturally or in the same form in the plant itself as we find it in
its natural state (Anon., 2005g).
iii) Super critical fluid extraction
Super critical fluid extraction (SFE) with respect to the extraction
of essential oils involves the use of carbon dioxide as the solvent. SFE is
a relatively new process, which uses carbon dioxide in the supercritical
state to dissolve soluble material out of the plant matrix. This process
gives a better quality extract but the capital costs are slightly higher.
Carbon dioxide is cheap, inflammable, and leaves no detectable residue.
A typical SFE process consists of two major segments, the extractor and
the separator. The material to be extracted is packed in to the extractor
and supercritical carbon dioxide enters the extractor where it dissolves
the volatile compounds in the plant material. The carbon dioxide and the
extract then goes to the separator where the pressure is below critical
thereby allowing the carbon dioxide to revert to the gas phase and
deposit the extract. The CO2 can then be recycled to the extractor vessel.
In order for the CO2 to be in the super critical state, the pressure and the
temperature must be above the critical point of CO2, i.e. 74 bars and
31°C (Anon., 2005 h).
14
iv) Liquid carbon dioxide for extraction
The use of liquid carbon dioxide as a solvent for fruit juice
concentrate extraction was reported earlier by Horvath (1939).
Subsequently, Francis (1954) presented an extensive experimental data
on solubility studies of different organic compounds like aliphatics,
aromatics, hetercylics, alcohols, esters, amines, nitriles and phenols with
liquid carbon dioxide and this work is the mile stone for carbon dioxide
extraction. Then the same technique was applied for extraction of aroma
and specially chemicals. It has been found that liquid carbon dioxide is
completely miscible in essential oils and the components like aldehyde,
ketones, esters and alcohols of essential oils have got good solubility in
liquid carbon dioxide while protein, starch, mineral salts and water are
insoluble in liquid carbon dioxide. The essential oils obtained by liquid
carbon dioxide extraction are superior in comparison to steam distillation
and solvent extraction. Recently, number of experimental results has
been reported on natural product extraction such as phyrithrins from
pyrethrum flower, essential oils from anise, carway, clove, staranise and
cinnamon and ginger (Naik et al., 1988).
2.4 Equipment for Distillation
Distillation tests conducted by the method based on the
determination of two parameters, the “increment parameter” and the
“basic time parameter” after dimensioning of a still suitable for the
processing of the plant could be made (Denny, 1991).
A portable distillation unit working on fuel wood was designed and
fabricated for field distillation of eucalyptus hybrid foliage. Under
optimum conditions, 1-1.8% (average-1.43%) of oil was distilled with this
15
unit, which is higher than that obtained with stationary stills of larger
dimensions. More than 95% of oil could be distilled out in the first two
hours of distillation, of which the first hour collection (about 75%) was
found to be more of cineole than the second hour collection. This unit
could be used with advantage for distilling oils from other plant materials
(Theagarajan et al., 1993).
Rao et al. (1999) reported about field distillation, using a 1000 kg
capacity distillation vessel using steam at about 2 bar pressure. It took
120 min to what was considered a full extraction and about 60 min to
obtain 90% of the total oil extracted.
2.4.1 Certain Conditions that affect the distillation
During distillation, a number of parameters that influence the
distillation of essential oils from plant materials such as : Storage,
Charge, Period of collection, Conditions of herb, Comminution
/disintegration process, Distillation period, Temperature, Other
constituents present, Condensation of the constituents and pH of
distillation water (Rajendra Prasad et al., 1987).
2. 5 Essential Oil Recovery
Patchouli yielded 3.27 % of the volatile oil on steam distillation and
only 2.98% on water distillation. The steam distillation in certain plant
materials has been found to increase the total yield of oil (Guenther,
1948).
Denys et al. (1990) compared different extraction methods for
rapid determination of essential oil content and composition of basil. It
16
was noticed that the yield of essential oil was consistently higher from
steam distillation than hydro distillation.
Singh and Maheshwari (1997) compared the yield of essential oil
by hydro distillation against CO2 extraction from callistemon, Murraya,
Lantana, Tagestes and Ocimum plants and reported that there was
increase in yield with supercritical CO2 extraction when compared to
hydro distillation process. Extraction using liquid CO2 was convenient
and superior in terms of both quantity as well as quality of the extracts
as compared to hydro distillation process. It was reported that the
terpene compounds of the essential oil got oxygenated resulting in
constant deterioration with time in the quality of oils obtained by hydro
distillation process.
2.6 Effect of Variety on Oil Content and Oil Yield
Buitkhi et al. (1975) observed that the essential oil of mint species
varied from 1.5% in Menthe silvestris to 2.5% in Menthe lavanduliodora.
Radhakrishnan et al. (1991) reported that shaded environment
yielded higher herb and oil of patchouli. This study was conducted in
Kerala where higher temperatures prevail (max. temp. often>35°C)
compared to the present site (max. temp. -26 to 33°C) during crop growth
period. Therefore, under mild temperature conditions, shading may not
create significant differences in patchouli yield. However, more
investigations are required to study the influence of shade under
different temperature regimes.
Vasundhara et al. (1992) reported that the application of GA3 at
200 PPM increased the fresh herb yield which resulted also in the
maximum recovery in majoram.
17
Maheshwari et al. (1993) reported that the essential oil content in
patchouli was maximum in Indonesia cultivars (2.71%) followed by
Singapore (2.5%) and Malaysian cultivars (2.4%) ; while essential oil yield
per maximum in Singapore cultivar (7.9 ml), followed by Indonesia (6.36
ml) and Malaysian cultivars (4.66 ml).
A field experiment was conducted in a red loam soil under semi-
arid tropical conditions to investigate the influence of partial shade(50%)
on the yield and quality of patchouli oil. Patchouli (Pogostemon cablin)
leaves contained 67% more chlorophyll under shaded environment
(Prakasa Rao et al., 1997).
Ramachandra et al. (2003) studied the effect of varieties and
spacing on growth, yield and quality of patchouli (Pogostemon patchouli
Pellet). They reported that cv. Java was more robust and recorded higher
dry herbage yield compare to cv. Johore had higher essential oil content
(2.7%) and the patchouli oil content in the oil was also high (44.7%)
when compared to cv. Java.
Oil recovery studies conducted on patchouli (Pogostemon cablin)
indicated that almost 100% oil was recovered with in 3 h in case of fresh
leaf (80-87% moisture). Semi-dried leaf (30-40% moisture) took about 5-6
h for recovery of 80-90% oil, while more than 90% oil was recovered with
in 9 h of distillation in case of dried leaf (10-20% moisture). Shade drying
of leaf and storage up to 150 days seemed to be congenial condition for
maximum recovery of oil. Ageing period exceeding 150 days for both
shade and sun drying of leaf had negative effect on oil recovery. Patchouli
alcohol was found to be maximum (42.37%) when dried leaves were
distilled for 11 h (Sarma and Sarma, 2003).
18
2.7 Distillation Process Variables
Nair et al. (1980) conducted an experiment at lemongrass research
station to study the effect of oil of different steam pressures on the yield
and quality of oil of lemongrass during steam distillation. They reported
that the yield of its oil and its critical content increased when steam
pressure was increased from 5 to 20 lb/inch² though it was not
statistically significant.
Prasad et al. (1987) reported that during distillation of almost all
medicinal and aromatic herbs, greater part of the constituents distilled
out with in the first two hours of distillation. Relatively long action of
steam or boiling water on plant material affects some of the more delicate
constituents of the oil deleteriously and hydrolysis, polymerization and
resinification may take place. Higher boiling constituents, if partly
soluble in water, are not carried by steam and hence, cannot be isolated
even after prolonged distillation. As a result of this, the distilled oil does
not always represent the natural oil as it originally occurred in the plant.
A portable distillation unit working on fuel wood was designed and
fabricated for field distillation of eucalyptus hybrid foliage by
Theagarajan et al. (1993). Under optimum conditions, 1-1.8% (average
1.43%) of oil could be distilled with that unit which was higher than that
obtained with satisfactory stills of larger dimensions. They also reported
that more than 95% of the oil distilled out in the first two hours of
distillation.
The herbs which contain high boiling oils that are chemically
stable at higher temperature (associated with high pressure distillation)
are best distilled under pressure (Varshney, 1993).
19
Waikhom et al. (1995) studied the essential oil yield in relation to
duration of distillation and stages of bud of clove. They reported that the
soaked cloves released the oil more rapidly (compared to the dry ones)
both in whole and powdered buds.
The study on comparative oil yield at different biomass to water
ratio carried out for eucalyptus leaves by Rath et al. (1997) showed that
the ratio of 1:7 was optimum and gives the highest oil yield. Also the
quality of the oil was transparent and excellent.
Tandon et al. (2002) conducted a study on the effect of steam
injection rate and steam inlet pressure on the distillation of the essential
oil of Menthe arvensis. It was reported that the steam pressure of the
order of 10 psig and injection rate in the range of 5-10 kg/h were optimal
for obtaining better yield of the essential oil.
2.8 Essential Oil Quality
The oil of patchouli is said to contain about 97% of compounds
which have almost no influence on its aroma. Of these, 40-45% belongs
to sesquiterpene group and the balance seems to consist of patchouli
alcohol. The oil contains small amount of benzaldehyde, eugenol,
cinnamic aldehyde, an alcohol with a rose like fragrance, a ketone with
orris like odour, another ketone, two bases possessing a strong
benumbing odour, azulene and a sesquiterpene alcohol – Patchoulene, γ-
guaiene,α-bulnesene,α-terpene cadinene,benzaldehyde and patchouli
alcohol have been identified chromatograghically (Guenther, 1952; Bates
and Slagel, 1962).
20
In patchouli, Haripraksha Rao and Vasantha Kumar (1983)
observed leaf reddening and attributed it to iron toxicity and in balance
in nutrient concentration also resulted in low amount of essential oil
production in affected plants compared to healthy plants. Hence, the
production of high quality oil in patchouli plants mainly depends on
balanced nutrition.
Leaves of patchouli (Pogostemon cablin) from various geographical
locations were extracted and the distilled oil subjected to analysis by gas
chromatography, gas chromatography – mass spectrometry and nuclear
magnetic resonance. More than 16 compounds were dectected, of which
11 were identified as alpha/beta/and delta-patchoulene, beta-elemene,
beta- caryophyllene, alpha/ and delta- guaiene, seychellene, alpha-
bulenese, delta-cardinene, pogostol (tentative identification) and
patchouli alcohol. Patchouli oil content was 32-37% and found to be the
most odour-intensive constituent of the oil (Dung et al., 1990).
The testing and analysis of the essential oils extracted for refractive
index, relative density, acid value and the geraniol content was carried
out as per standards (Datta and Malik, 1993). The chemical composition
of any essential oil also reveals its quality (Lawrance, 1989). For
comparing the quality of the oil with any other oil extracted by the
conventional steam distillation process, a few samples of the oils
commercially being produced by a local company M/s Konark Paper
Industries Limited (KPIL) by steam distillation were collected and tested
under similar conditions (Rath et al., 1997).
The essential oil from Indonesian patchouli (P. cablin) was analyzed
qualitatively and quantitatively by gas chromatography (FID) and gas
chromatography/mass spectrophotometery. Using different ionization
techniques in mass spectrometry (EI, NCI and PCI with ammonia and
21
deuterated ammonia as reagent gases), 41 compounds were separated,
and 28 of which (92% of the total oil) were identified. Four new
compounds were found in the oil; γ-gurjunene (2.2%), germacrene D
(0.2%), aciphyllene (3.4%) and 7-epi-α-selinene (0.2%) (Bure and Sellier,
2004).
Narayanan (2004) observed that Indian patchouli oils were light
yellow in colour when compared to darker oils from Indonesia due to
better distillation practices followed in India especially the use of
stainless stills. The use of mild stills in Indonesia for patchouli oil
distillation resulted in picking up of colour by the essential oil.
The essential oil from leaves of Cinnamomum tamala L. (Lauraceae)
was obtained by hydro distillation and the yield was 2.42% on dry weight
basis. The oil was analyzed by gas chromatography-mass spectrometry.
51 compounds accounting for 93.03% of the oil were identified. Eugenol
(81.69%) was the most abundant with the appreciable amounts of α –
phellandrene (4.08%) and cymol (1.37%) (Rana and Blazquez, 2005).
MATERIAL AND METHODS
22
III MATERIALS AND METHODS
This chapter deals with the materials used and various
procedures/methods followed during the course of research study titled
“Agro-Processing of Patchouli (Pogostemon cablin Benth.) for Efficient Oil
Extraction”. It gives details of various unit operations carried out on
patchouli like drying, extraction of essential oil, quality analysis of the
essential oil extracted and development/testing of a small pilot scale
distillation unit for patchouli oil extraction.
The experiments were mostly carried out in the Post Harvest
Technology Scheme, Department of Horticulture, University of
Agricultural Sciences, Gandhi Krishi Vignan Kendra, Bangalore, and in
Indian Institute of Science, Bangalore. The quality analysis of patchouli
oil samples was however, done at Central Institute of Medicinal and
Aromatics Plants (CIMAP), Bangalore.
3.1 Raw Materials
For drying studies, the fresh patchouli (cv. Johore) was obtained
from Department of Horticulture, UAS, Bangalore, and also from CIMAP,
Bangalore. The herbage was harvested at right stage and both leaves and
twigs in the ratio of 80:20 were taken for various drying experiments like
tray drying, shade drying and drying in ASTRA, (Waste Based Dryer). The
shade dried patchouli used for pilot scale steam distillation is, however,
obtained directly from the local farmer through the contact of M/s Flower
Valley Bio-tech Pvt, Ltd, Bangalore.
23
3.2 Drying Studies of Patchouli Herbage
Freshly, harvested patchouli crop was dried by three different
methods: i) Shade drying ii) Convective tray drying and iii) Drying using
ASTRA Model Waste Based Dryer. In tray drying, five different drying
temperatures namely, 30, 40, 50, 60 and 70°C were attempted and the
initial drying bed thickness (depth) of fresh herbage was kept uniformly
at 100 mm.
3.2.1 Shade drying
During shade drying, the fresh patchouli herbage was spread on a
stainless steel tray and was allowed to dry in a well ventilated room (Plate
3.1). The initial drying bed thickness was 100 mm and the herbage was
turned frequently. Though slight variation in initial moisture content of
herbage was noticed, the moisture content was normalized at the
beginning of the experimentation to around 80% (wb). The average
ambient temperature and relative humidity of the room was recorded
using a Digital Thermo-Hygrometer. During shade drying, the ambient
temperature varied from 21.0-24.4°C and the relative humidity varied
from 40-81%. The periodic weight loss of the samples was recorded at
every one hour interval using a sensitive electronic balance (make:
Essae-DIGI, model: DS-450) and the moisture content at a given time
was estimated accurately by Toluene Distillation Method (AOAC, 1995).
Shade drying was continued until there was no more weight loss by the
sample as indicated by constant consecutive weight readings. At this
point, the herbage was assumed to be dried to its stable equilibrium
moisture content of around 11-12 % (wb). At the end of drying, in the
dried samples were stored in sealed LDPE (200g) bags until the oil
extraction was carried out by hydro distillation technique.
24
Plate 3.1 Shade drying
Plate 3.2 Convective Tray Dryer
25
3.2.2 Tray drying
3.2.2.1 Convective tray dryer
The experimental Tray Dryer (Plate 3.2) consisted of an insulated
cabinet of 18”x18”x24” (internal dimensions) with a door. Inside the
cabinet, 4 stainless steel trays could be placed one over the other with
some gap in between them. There was a heating unit situated at the
bottom of the cabinet consisting of three resistive type electrical heaters
of 1 Kw capacity each that actually heated up the drying air. The heating
unit was insulated using asbestos sheet and glass wool. The heated air
was circulated inside the cabinet using a fan operated by a 1/13 hp
electric motor. Two ventilation vents are provided on the side walls of the
cabinet to partially exhaust the wet air out of the dryer. The temperature
of the hot air was controlled with the help of a digital temperature
controller situated at the top of the cabinet and the temperature could be
maintained from ambient temperature to 175°C ±2°C using a thermostat
control.
3.2.2.2 Drying of samples
The tray dryer was put on for about 10-15 min before the start of
the experiment for initial warming up of the system. When the desired
drying air temperature was attained, the patchouli samples in sample
trays were placed inside the drying chamber and were dried at selected
temperatures. Tray drying experiments were conducted with samples of
400g fresh herbage. Small sample trays of 100 mm depths were
separately fabricated with stainless steel wire mesh and were used as
sample holders. The herbage was spread evenly to 100 mm initial bed
depth and the sample trays were placed inside the tray dryer (Plate 3.2).
26
The drying experiments were conducted at five different temperatures of
30, 40, 50, 60 and 70°C. The trials were replicated thrice for each drying
temperature selected. During drying, periodic weight loss (at hourly
intervals) of the samples were recorded using a sensitive electronic
balance and the moisture contents at a given time were estimated
accurately by Toluene Distillation Method (AOAC, 1995). Tray drying was
continued until there was no more weight loss by the sample as
indicated by constant consecutive weight readings. At this point, the
herbage dried was assumed to be dried to its stable moisture content of
(around 11-12 % (wb)). At the end of the drying, the extraction of
essential oil from dried samples was carried out by hydro distillation
technique.
3.2.3 Tray drying using ASTRA Model Agricultural Waste Based Crop
Dryer
3.2.3.1 ASTRA Model Agricultural Waste Based Crop Dryer
Center for Sustainable Technologies, Indian Institute of Science,
Bangalore has developed a simple batch type tray drier popularly known
as ASTRA Model Agricultural Waste Based Crop Dryer based on the
principle of a fuel efficient wood stove (Plate 3.3). In this dryer, hot flue
gases is conveyed through a duct that constantly heated the sucked
drying air. The heated drying air is made to pass over the material kept
in stainless steel trays in an orderly fashion due to natural convection.
The drying air removes the moisture from the material to be dried before
being vented off separately at the top. The design of dryer is such that
the cycle of heating, cooling, humidifying and reheating of drying air
takes place throughout its passage i.e., from bottom to the top of the
drier. The large area of flue duct contacting drying air (due to the internal
design for ordered flow of air) results in high heat transfer efficiency and
thus over 90% of heat generated by combustion is transferred to drying
27
Plate 3.3 ASTRA Dryer
Plate 3.4 Tray of ASTRA Dryer
28
air. The bottom flue duct ensures safe hot air while reheating of the
cooled and humidified drying air with in the dryer enables better drying
of product. Temperature of drying air could be controlled reasonably by
adjusting the burning rate of the fuel.Though the dryers of different
capacities are available, the one used in this study had a 7.8 sq.m
stainless steel tray area for drying the product. The cost of the equipment
is Rs 40,000 which works out to Rs 5200 per sq.m of stainless steel tray
area.
3.2.3.2 Drying of samples
The dryer was fired by using agricultural waste like wood
briquettes (Plate 3.5) for about 30-45 minutes before the start of the
experiment for initial warming up of the system. The temperature of
drying air at different levels could be maintained between 45-95°C by
controlling the rate of burning of fuel. When the desired drying air
temperature was attained, the fresh patchouli samples (in sample trays)
were dried at required temperature. Tray drying experiments were
conducted with samples of 3 kg fresh herbage. Sample trays of 100 mm
depth were used as sample holders (Plate 3.4) and the herbage was
spread evenly on trays to the required depth of 100 mm (initial bed
depth). The drying experiment was replicated thrice. During drying,
periodic weight loss of the samples (at hourly intervals) was recorded
using a sensitive electronic balance and the drying air temperature was
recorded at every one hour interval using a dial type thermometer (Plate
3.6) .The moisture content of patchouli sample at a given time was
estimated by toluene distillation method (AOAC, 1995). Drying was
continued until there was no more weight loss by the sample as
indicated by constant consecutive weight readings. At this point, the
herbage dried was assumed to be dried to its stable equilibrium moisture
29
Plate 3.5 Fuel Briquettes
Plate 3.6 Dial Thermometer
30
content of around 11-12 % (wb). After drying, the extraction of essential
oil from dried patchouli was carried out by hydro distillation technique.
3.3 Determination of Moisture Content of Patchouli Herbage
Moisture content of patchouli herbage samples was determined by
Toluene Distillation Method (Plate 3.7) as described in AOAC (1995).
Materials: 1000 ml short neck round bottom flask, 10 ml capacity
moisture receiver, 400 mm condenser and heating unit.
Reagents required: Toluene
Procedure: 10 g of patchouli herbage (8 g leaves and 2 g tender stem)
was placed in a 1000 ml distillation flask. Toluene was added to cover
the sample completely (never more than 250 ml). The receiving tube was
filled with toluene by pouring it through top of the condenser. A loose
cotton plug was inserted on top of condenser to prevent condensation of
atmospheric moisture into the tube. Using an electrically controlled
heating mantle, the toluene in the flask was brought to its boiling point
so that the moisture present in the sample also distilled at the rate of 2
drops per second. Gradually heating was intensified so as to distill at
about 4 drops per second and the distillation was continued till no more
moisture was collected in the condenser. It took about 3 hours to collect
all the moisture available in the sample. The amount of water collected in
the graduated receiver was directly proportional to the moisture present
in the sample.
3.4 Essential Oil Extraction by Hydro Distillation
The extraction of patchouli essential oil from the experimental samples of
dried patchouli herbage (by convective tray drying, shade drying, drying
in ASTRA model dryer) was done in the laboratory by hydro-distillation
technique (AOAC, 1995) using a Clevenger’s Apparatus (Plate 3.8).
31
Plate 3.7 Moisture Determination Apparatus
32
Apparatus: a) Volatile oil trap: Clevenger type with standard taper joints
for oils having densities near or less than that of water.
b) Flask 2000 ml round bottom, short neck with standard 29/42 taper
joint.
Procedure: A known quantity of dried patchouli herb (50 g) in the ratio
of 80:20 (leaves: tender sticks) was transferred in to the round bottom
flask and distilled water was added until the whole material was
immersed in the water (1000 ml). Well cleaned (with chromic acid)
Clevenger’s oil trap was fitted in the flask and the trap was filled with
distilled water. The flask was placed on an electrically heated mantle and
the contents were allowed to boil slowly. The steam passing out of the
flask along with the volatile oil was cooled in the water cooled condenser
and was collected in the oil trap. The distillation was carried out for
about 6 h (i.e., until there was no further oil collection). The patchouli oil
being lighter than water and immiscible formed a separate layer over the
water column in the Clevenger’s trap. The amount of patchouli oil
collected could be directly read from the graduated oil trap and thus oil
extraction in percentage (ml/100 g sample) was worked out.
3.5 Steam Distillation of Patchouli Essential Oil in Pilot Scale Unit
3.5.1 Pilot Scale Steam Distillation Unit
In the present study, though there was a mandate to develop a
pilot scale distillation unit, it could not be taken up due to exorbitant
cost involved for the fabrication of stainless steel unit. Therefore, an
available laboratory model pilot scale steam distillation unit in the
Department of Horticulture was made use of in the present study. The
pilot scale steam distillation unit used for the extraction of essential oil
33
Plate 3.8 Clevenger’s Essential Oil Distillation Unit
34
from shade dried patchouli herbage is given in Plate 3.9. The unit
consisted of: a) Steam generator, b) Distillation still, c) Condenser and
d) Essential oil receiver
The steam generator was an electrically heated boiler that
generated live steam at about 1 kg/cm2 pressure for distillation. During
operation, the water level inside the boiler was maintained manually so
that the boiler was not dried out. The distillation still was basically a
double walled vertical drum (inside wall made up of stainless steel) with
a tight lid on the top. The inside diameter of the still was 0.54 m and the
height of the still was 0.6m (sample holding height), thus having a
volumetric capacity of 0.5 m3. Inside the still, there was a perforated
false floor on which the dried patchouli herbage to be extracted (charge)
is placed. The steam entered the still at the bottom, rose through the
charge extracting volatiles and came out of the still at the top to enter
into the condenser. The condenser was a double pipe heat exchanger
where in the steam coming along with the essential oil vapour from
distillation still was condensed by cooling water circulated in the outer
tube. The condensate that contained water and essential oil was collected
in a receiver tank and the condensate was allowed to settle overnight for
rough separation of essential oil from water layer.
3.5.2 Extraction of Patchouli Oil in Pilot Scale Steam
Distillation Unit
During pilot scale distillation study, the patchouli bed packing
density inside the still and distillation time were varied to study the
quantity and quality of oil distilled as given below:
Independent variables:
Packing bed density (kg/0.5 m³): 4, 5 and 6
Distillation time (h) : 3, 4 and 5
35
Dependent variables:
Essential oil recovery
Quality of distilled essential oil
Total Treatments: 3 x 3 = 9
Replications : 3
Design : Factorial CRD
A known quantity of shade dried patchouli herbage directly
obtained from farm was packed uniformly in the distillation still and the
lid of the still was closed air-tight. The leaf to stick ratio of the herbage
was found to be about 60:40. The electrically heated boiler was switched
on and the water level in the boiler was manually maintained to a
required level. It took about 15 min for the boiler to issue steady steam
at a pressure of about 1 kg/cm². The distillation time was counted only
after the steam at steady pressure entered the distillation still. Thus the
steam while passing through the charge heated up the herbage. The
essential oil present in the cells of the patchouli herbage came out of the
cellular material due to vaporization and it rised along with steam. The
essential oil vapour and steam that came out of the distillation still were
condensed back to liquid phase in the water cooled condenser and the
condensate was collected in the receiver tank. The condensate was
basically a two-phase system with top layer of patchouli oil floating over
the heavier bottom layer of water. The condensate in the receiver tank
was allowed to stand for sufficient time (over night) so that the patchouli
oil separated out as far as possible from the water layer. After reasonable
separation in the receiver tank, the essential oil was further separated
from the water phase using a Separating Funnel (Plate 3.10). The oil was
still turbid due to the presence of some small tiny water droplets and
therefore, the oil was further dried using sodium sulphate. Then it was
36
Plate 3.9 Pilot Scale Patchouli Steam Distillation Unit
Plate 3.10 Essential oil separating funnel Plate 3.11 Patchouli essential oil
37
filtered through a Whatman filter paper to get clear essential oil (Plate
3.11). The clear essential oil thus obtained was stored in coloured glass
bottles till further analysis.
Quality Analysis of Essential Oil
The patchouli essential oil samples collected from different
experiments of the present study were subjected to quality analysis. The
composition of the oil was determined by the method of Gas-Liquid
Chromatograpy. The optical rotation and refractive index of essential oil
samples were determined using a Polarimeter and Abbey Refractometer,
respectively.
3.6.1 Gas Chromatographic analysis
Gas Chromatography (GC), a method for measuring the volatile
chemical constituents, is used to determine the composition of the
patchouli essential oil. It is one of the four objective tests done to
determine the quality, identity and purity of every essential oil. GC
analysis produces a “finger print” of the oil by showing the quantitative
presence of each chemical compound. In the present study, Gas–Liquid
Chromatography analysis of the patchouli essential oil samples were
conduced in Central Institute for Medicinal and Aromatic Plants,
Bangalore. The tests were conducted for four major components: β-
patchoulene, -guaiene, -bulnesene and patchouli alcohol. The results
were obtained in percent composition.
In the present study, the gas chromatographic analysis (IS 326:
Part 19) of patchouli essential oil was carried out using a Gas
Chromatograph having capillary column (Plate 3.12). The duration of test
in the GC with capillary column was 60 minutes. The computerized data
38
acquisition system collected the real time GC data that was analyzed
with the help of dedicated software supplied with GC.
Procedure (IS: 3398 - 2003): A small amount of essential oil was
introduced into a gas liquid partition column. The various components
that were volatile under the conditions of test were vaporized and were
transported through the test column by a carrier gas. The separated
components were measured in the effluent by a Flame Ionization
Detector and recorded as a chromatogram. The chromatogram was
interpreted by applying component attenuation and detector response
factors to the peaks, areas and the relative concentrations of various
constituents were determined by relating the individual peak responses
to the total peak responses. The following are the test conditions during
GC analysis:
Gas chromatographic conditions
Polar
Column Capillary, silica, length 30m, internal diameter 0.25mm
Stationary Phase
Polyethylene glycol 20M, film thickness 0.255 micrometer
Oven temperature programming
100 to 220°C at the rate of 2°C / min and isothermal for 30 min at 220°C
Injector temperature
250°C
Flame ionization detector temperature
250°C
Carrier gas
Nitrogen, 1 ml/min
Split ratio
1:100
Volume Injected
0.2 µl
39
3.6.2 Determination of Optical Rotation of Patchouli Essential Oil
Principle: When a beam of plane polarized light is passed through a
solution of compound such as (S)-alanine, the plane of polarization of the
light that emerges is rotated relative to the original plane. This
phenomenon is known as optical activity, and the compounds that rotate
the plane of polarized light are said to be optically active. The rotation of
polarized light through a liquid establishes its optical activity whether
dextrorotatory (bends light to the right) or laevorotatory (bends light to
the left). The reading is compared to the established standards;
significant deviation from the standard may indicate impurities and give
cause for further investigation.
Apparatus: Polarimeter (Plate 3.13), source of light- sodium vapour
lamp, distilled water, filtering device.
Procedure: The polarizer was directed towards monochromatic source of
light. The polarimeter tube (200 mm) was completely filled with distilled
water and its lid was closed tightly taking care to see that no air bubble
was formed. This tube was placed in the sample holder between the
polarizer and the analyser of the polarimeter. The analyser was rotated
till the tint of passage i.e., the two halves of the field of view was of
uniform intensity and colour. The angular reading (Ro) of the analyser
was noted in the main and the vernier scales. The essential oil was then
filled in the polarimeter tube as explained before and the tube was
mounted again between the polarizing and analyzing nicol prisms in the
sample holder. The analyser was rotated clockwise or anticlockwise until
the field of view was of uniform intensity and colour. The angle of
rotation (R) was again noted. Then the optical rotation was calculated as:
Optical Rotation = (R - Ro)
40
Plate 3.12 Gas Chromatograph
Plate 3.13 Polarimeter Plate 3.14 Refractometer
41
3.6.3 Determination of Refractive Index of Patchouli Essential Oil
The index of refraction is related to the physical structure of the
medium through which light is passing. Refractive index is defined as the
ratio of the velocity of light in a vacuum to its velocity in a specimen
(transparent). Higher the refractive index, greater the amount of
dispersion, which increases the brilliance of the material. The refractive
index values for the patchouli essential oil samples were determined
using Abbey Refractometer (Plate 3.14).
Procedure: A drop of the patchouli essential oil sample was paced on
the cleaned fixed prism and slowly the two prisms of the refractometer
were brought together and clamped. The refractometer was aligned to the
light source for proper illumination. The border line was brought into
field of view using coarse adjustment (lower right hand side). The border
line was dark blue on the other side. The cross wires were observed
through the eye piece and the border line was brought up to the
intersection of cross wires by means of the coarse or fine hand controls.
The refractive index reading of the patchouli essential oil was read
directly on the side scale of the refractometer through the magnifier.
After taking the reading, the prisms were opened and carefully cleaned
with a piece of lens paper.
3.7 Statistical Analysis
The statistical analysis of data in the present study was done using
the AIRS Computer Facility of University of Agriculture Sciences,
Bangalore, as per the statistical design employed. The computer
programme was developed in-house by Department of Agricultural
Statistics in FORTRAN language specifically for the VAX Platform.
EXPERIMENTAL RESULTS
42
IV. EXPERIMENTAL RESULTS The results of the experiments conducted during the course of
research study titled “Agro-Processing of Patchouli (Pogostemon cablin
Benth.) for Efficient Oil Extraction” are presented in this chapter.
4.1 Drying Studies of Patchouli Herbage
The drying characteristics of fresh patchouli herbage dried at
different temperatures in a convective tray dryer are depicted in Fig. 4.1
while the shade drying characteristics are given in Fig. 4.2. The drying
behaviour of fresh patchouli in ASTRA Model Agricultural Waste Based
Dryer is presented in Fig. 4.3.
4.1.1 Drying characteristics of patchouli in Tray Dryer
The drying behaviour of freshly harvested patchouli at different
temperatures in a convectional tray dryer is given in Fig. 4.1. The
moisture loss was relatively high during the initial phase of drying, say
up to 65-70 % moisture content and the patchouli lost its moisture more
rapidly at all drying temperatures .However, when drying continued the
rate of moisture reduction slowed down and when the herbage almost
reached its equilibrium moisture content the loss of moisture from the
sample is very slow. It could be observed that the drying time required to
dry the herbage from a moisture content of about 80 % (wb) to around 11
% (wb) varied considerably depending upon the temperature of drying.
For 100 mm initial drying bed depth, the drying time required at 30, 40,
50, 60 and 700C temperatures were 13, 12, 11, 7 and 6 h, respectively.
The influence of drying temperature on tray drying time of patchouli was
clearly discernible. As the drying temperature increased, the rate of
drying generally increased resulting in lesser time. For e.g., at 300C, it
43
0
10
20
30
40
50
60
70
80
90
0 2 4 6 8 10 12 14Drying time (h)
Moi
stur
e co
nten
t (%
wb)
70°C
60°C
50°C
40°C
30°C
╚
Fig 4.1 Drying characteristics of patchouli herbage in tray dryer
0
20
40
60
80
100
0 10 20 30 40 50 60
Drying time (h)
Moi
stur
e co
nten
t (%
wb)
R1
R2
R3
Fig 4.2 Drying behaviour of patchouli herbage under shade
R1, R2 and R3 – Trial runs
44
0102030405060708090
0 2 4 6 8 10 12 14 16
Drying time(h)
Moi
stur
econ
tent
(%w
b) R1
R2
R3
` Fig 4.3 Drying behaviour of patchouli herbage in ASTRA Model
Waste Based Crop Dryer
R1, R2 and R3 – Trial runs
0102030405060708090
100
0 2 4 6 8 10 12 14 16
Drying time (h)
Dry
ing
tem
pera
ture
(°C
) T1T2T3T4T5T6T7
Fig 4.4 Drying air temperature variation at different levels inside ASTRA Model Dryer during patchouli drying
T1, T2, T3, T4, T5, T6 and T7 – Temperature of drying air
measured at different levels from bottom to top inside
ASTRA Dryer
45
required about 13 h of drying time where as at 400C, it required only
about 12 h of drying time (for the same 100 mm of initial bed thickness).
Similar trend in reduction of drying times were observed at 50, 60 and
700C temperatures also.
4.1.2 Shade drying characteristics of patchouli
Shade drying behaviour of freshly harvested patchouli dried at an
initial drying bed thickness of 100 mm are depicted in Fig. 4.2. Under
the moderate ambient conditions of temperature (21–24.4°C) and relative
humidity (40-81%) that prevailed at Bangalore during shade drying, the
fresh patchouli herbage required about 54 h of drying time to dry the
fresh patchouli herbage at an initial moisture content of 80 %(wb) to a
final moisture content of 11-12 %(wb). The reduction in moisture content
with time was almost uniform but very slow. For the same 100 mm initial
drying bed depth, the tray drying time required were much lower than
the shade drying time at drying temperatures of 30, 40, 50, 60 and 700C
drying temperatures.
4.1.3 Drying characteristics of patchouli in ASTRA Model Agricultural Waste Based Crop Dryer
The drying behaviour of freshly harvested patchouli in ASTRA
Model Agricultural Waste Based Crop Dryer is depicted in Fig 4.3. It was
observed that the drying air temperature inside this ASTRA model Dryer
varied from 45 to 95°C during drying experiments and the drying air
temperature distribution at various levels inside the dryer is presented in
Fig.4.4. For 100 mm of initial drying bed thickness, the fresh patchouli
herbage required about 14 h of drying time to dry from an initial
moisture content of 80% (wb) to a final moisture content of 11-12 % (wb)
in ASTRA Dryer. The reduction in moisture content with time was almost
uniform but still very slow as compared to convective tray drying.
46
4.2 Effect of Drying Techniques on Essential Oil Yield
The quantities of essential oil extracted by hydro-distillation using
Clevenger’s apparatus from samples of patchouli dried under shade and
in the laboratory convectional tray dryer and in ASTRA Dryer are
presented in Fig. 4.5. It could be observed that the mean essential oil
yields were about 2.41% in shade dried sample, 2.25 – 2.40% in tray
dried samples and 2.24% in samples dried in ASTRA Dryer (Appendix –
A). Statistical analysis of data indicated that there was no significant
difference between various drying techniques with respect to essential oil
yield.
4.3 Effect of Drying Methods on Quality of Essential Oil The patchouli essential oil distilled from the patchouli herbage
dried in tray dryer, ASTRA dryer and by shade were analyzed for quality.
Gas chromatographic analysis of patchouli oils was done to determine
the various constituents of patchouli oil and a sample graph obtained
during the analysis is shown in Fig. 4.6. Refractive index was also
determined for various oil samples using Abbey Refractometer.
Considerable variation was observed in the composition of four major
patchouli oil constituents namely, β-patchoulene, -guaiene, -bulnesene
and patchouli alcohol.
4.3.1 Patchouli alcohol
The effect of drying methods of patchouli herbage on the patchouli
alcohol content of the extracted patchouli essential oil (from it) is
presented in Fig. 4.7. It could be observed that the patchouli alcohol
content was highest (66.26%) in the patchouli essential oil sample
extracted from the herbage dried at 70°C in convective tray dryer. And it
was observed to be 64.54, 64.19, 63.87 and 57.15% in the other
47
2.15
2.2
2.25
2.3
2.35
2.4
2.45
30 40 50 60 70 Shadedrying
ASTRAdrying
Drying Temperature (°C)
Esse
ntia
l Oil
Rec
over
y (%
)
Fig 4.5 Essential oil recovery from patchouli herbage dried under shade, in tray dryer at different drying temperatures and in ASTRA dryer
48
Fig 4.6 Gas chromatographic profile of patchouli oil
49
0
20
40
60
80
30 40 50 60 70 Shadedrying
ASTRAdrying
Drying temperature(°C)
Patc
houl
i Alc
ohol
Con
tent
(%)
Fig 4.7 Effect of drying of patchouli herbage on patchouli alcohol
content of extracted patchouli oil
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
30 40 50 60 70 Shadedrying
ASTRAdryer
Drying temperature(°C)
Bet
a Pa
tcho
ulen
e C
onte
nt (%
)
Fig 4.8 Effect of drying of patchouli herbage on β- patchoulene content of extracted patchouli oil
50
patchouli oil samples distilled from the herbage dried respectively at 50,
40, 60 and 30°C in convectional tray dryer. Similarly, the patchouli
alcohol content of essential oil from shade dried herbage was found to be
64.65 % while the sample dried in ASTRA Dryer had only 42.27%, much
less when compared to the patchouli alcohol contents of oils extracted
from the herbage dried in the tray dryer and by shade drying.
4.3.2 β-Patchoulene
The effect of drying methods of patchouli herbage on the β-
patchoulene content of the extracted patchouli oil (from it) is depicted in
Fig. 4.8. The β-patchoulene content was considerably higher in the
essential oil distilled from the tray dried patchouli herbage at 70°C
temperature (0.0302 %) when compared to the values of 0.0277 , 0.0249
, 0.0206 and 0.0103 %, respectively in the essential oils distilled from the
patchouli herbage tray dried at 60, 50, 40 and 30°C temperatures. The β-
patchoulene content of sample from the shade dried patchouli herbage is
comparable as tray dried sample (0.0249 %) and the least β-patchoulene
content of 0.0076% was noticed in samples from ASTRA Dryer.
4.3.3 α-Guaiene
From Fig. 4.9, it could be observed that the essential oil distilled
from patchouli herbage dried in ASTRA Dryer contained a -guaiene
content of 0.0991%. The essential oil distilled from the patchouli herbage
dried at 30, 40, 50, 60 and 70°C in tray dryer was 0.2352, 0.1452,
0.1629, 0.2397 and 0.0824 %, respectively. It could be observed that the
-guaiene content was 0.0401% in the essential oil distilled from the
shade dried herbage, which of course was less when compared to the -
guaiene content of oils extracted from the herbage dried in the tray dryer
and ASTRA Dryer.
51
0
0.05
0.1
0.15
0.2
0.25
0.3
30 40 50 60 70 Shadedrying
ASTRAdryerDrying Temperature(°C)
α- G
uaie
ne C
onte
nt (%
)
Fig 4.9 Effect of drying of patchouli herbage on α-Guaiene content of extracted patchouli oil
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
30 40 50 60 70 Shadedrying
ASTRAdryer
Drying temperature (°C)
Alph
a Bu
lnes
ene
Con
tent
(%)
Fig 4.10 Effect of drying of patchouli herbage on α-Bulnesene
content of extracted patchouli oil
52
4.3.4 α-Bulnesene
The effect of drying of patchouli herbage on the α-bulnesene
content of the patchouli oil extracted from it is depicted in Fig. 4.10. The
α-bulnesene composition was found to be 0.12904% in the essential oil
distilled from the herbage dried in ASTRA Dryer. The α-bulnesene
contents was 0.1278, 0.0571, 0.0512, 0.0407 and 0.0512 % respectively
in the essential oils obtained from the herbage dried in tray dryer at
temperatures of 60, 50, 40, 70 and 30°C while the above value was
0.1278 % in the oil distilled from the shade dried herbage.
4.3.5 Refractive index
The refractive index of patchouli oil samples distilled from
patchouli herbage dried under shade, in ASTRA Dryer, as well as in tray
dryer at different drying temperatures varied from 1.501 to 1.505 (Table
4.1). The refractive index values of patchouli oils obtained from different
samples of dried patchouli herbage did not show much variation and
neither the method of drying nor the experimental range of drying air
temperatures studied (30, 40, 50, 60 and 70°C) had any significant
influence on refractive index of oils extracted.
4.4 Pilot Scale Steam Distillation of Patchouli Essential Oil
Pilot scale steam distillation of shade dried patchouli herbage was
carried out at 3 different packing bed density levels of 4, 5 and 6
kg/0.5m3 and distillation time of 3, 4, 5 and 6 h to find out the essential
oil yields and quality.
53
00.5
11.5
22.5
33.5
4
0 1 2 3 4 5 6 7Distillation time (h)
Esse
ntia
l oil
yiel
d (%
)
Fig 4.11 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 4 kg/0.5m³
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6 7
Distillation time (h)
Esse
ntia
l oil
yiel
d (%
)
Fig 4.12 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 5 kg/0.5m³
54
00.5
11.5
22.5
33.5
0 1 2 3 4 5 6 7
Distillation time (h)
Esse
ntia
l oil
yiel
d (%
)
Fig 4.13 Effect of steam distillation time on patchouli essential oil recovery at packing bed density of 6 kg/0.5m³
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4 5 6 7
Distillation time (h)
Esse
ntia
l oil
yiel
d (%
)
Fig 4.14 Essential oil recovery from shade dried patchouli herbage
at various distillation time intervals (packing bed density of 4 kg/0.5m³)
55
0
5
10
15
20
25
30
35
40
45C
onte
nts
(%)
(1-3) h (3-4) h (4-5) hDistillation Period
Patchouli AlcoholAlpha-BulneseneAlpha-GuaieneBeta-Patchoulene
Fig 4.15 Variation in patchouli oil quality at different distillation
time intervals for packing bed density 4 kg/0.5m³
0
5
10
15
20
25
30
35
40
45
Con
tent
s (%
)
(1-3) h (3-4) h (4-5) hDistillation Period
Patchouli AlcoholAlpha-BulneseneAlpha-GuaieneBeta-Patchoulene
Fig 4.16 Variation in patchouli oil quality at different distillation time intervals for packing bed density 5 kg/0.5m³
56
Table 4.1 Effect of drying of patchouli herbage on the refractive
index of extracted essential oil
Temperature (°C)
R1 R2
Refractive Index Mean
30
1.502
1.504
1.5030
40
1.502
1.502
1.5020
50
1.502
1.503
1.5025
60
1.503
1.502
1.5025
70
1.504
1.503
1.5035
Shade
1.505
1.503
1.5040
Astra 1.501 1.501 1.5010
F- Test
NS
NS
NS
CD
-
-
-
NS - Not Significant
57
4.4.1 Influence of packing bed density and distillation time on patchouli essential oil yield
The effect of packing bed density and distillation time on patchouli
essential oil yield is presented in Fig.4.11 to 4.13. It could be observed
that the variation in packing bed density and distillation time had
significant influence on the essential oil yield.
At 4 kg/0.5m3 packing bed density, the patchouli essential oil
yields were 2.78, 3.06, 3.26 and 3.42 % respectively for 3, 4, 5 and 6 h
distillation time. At 5 kg/0.5m3 packing bed density, the patchouli
essential oil yields were 2.46, 2.74, 2.95 and 3.10 % respectively for 3, 4,
5 and 6 h distillation time. Similarly, at 6 kg/0.5m3 packing bed density,
the patchouli essential oil yields were 2.25, 2.54, 2.79 and 2.97%
respectively for 3, 4, 5 and 6 h distillation time. It was interesting to note
that the statistical analysis of essential oil yield data from pilot scale
distillation (Appendix-B) showed significant difference with respect to
both packing bed density and distillation time.
Further, from Fig. 4.14, it could be seen that the essential oil
recovery was faster at the beginning of steam distillation i.e., up to first 3
h and later on the oil yield was decreasing with time. Beyond 5 h of
steam distillation in the Pilot Scale Unit, very little oil was collected (at
packing bed density of 4 kg/0.5m3).
4.4.2 Influence of packing bed density and distillation time on patchouli essential oil quality
The compositions of patchouli essential oils extracted from shade
dried patchouli herbage using Pilot Scale Steam Distillation Unit at
different packing densities and distillation times were analyzed in a Gas
Chromatograph and the results are presented in Table 4.2. It could be
observed that the patchouli alcohol content varied from 34.74% in 4
kg/0.5m³, 34.92% in 5 kg/0.5m³, and 27.78% in 6 kg/0.5m³,
58
Table 4.2 Influence of packing density and distillation time on patchouli essential oil quality
NS – Not significant
Distill-ation Time (hr)
Packaging Bed Density
4 kg/ 0.5 m3
5 kg/ 0.5 m3
6 kg/ 0.5 m3
Patchouli alcohol
(%)
α- Bulnesene
(%)
α- Guaiene
(%)
β- Patchoulene
(%)
Patchouli alcohol
(%)
α- Bulnesene
(%)
α- Guaiene
(%)
β- Patchoulen
e (%)
Patchouli alcohol
(%)
α- Bulnesene
(%)
α- Guaiene
(%)
β- Patchou-lene (%)
3 4 5
25.15
36.18
42.89
21.95
19.94
18.21
16.14
12.33
9.77
0.0195
0.0171
0.0195
25.46
35.43
43.86
22.40
19.40
17.44
16.48
12.44
9.21
0.0100
0.0219
0.0177
23.33
29.58
30.42
22.74
20.52
14.89
16.68
13.74
8.56
0.0000
0.0000
0.0000
Mean 34.74 20.04 12.75 0.0187 34.92 19.75 12.71 0.0165 27.78 19.38 19.38 0.0000
F-test NS NS NS NS NS NS NS NS NS NS NS NS
59
α-Bulnesene content varied from 20.04% in 4 kg/0.5m³, 19.75% in 5
kg/0.5m³, and 19.38% in 6 kg/0.5m³, α- Guaiene content varied from
12.75% in 4 kg/0.5m³, 12.71% in 5 kg/0.5m³, and 19.38% in 6
kg/0.5m³, and β- Patchoulene varied from 0.0187% in 4 kg/0.5m³,
0.0165% in 5 kg/0.5m³, and 0.000% in 6 kg/0.5m³ for different samples
of essential oils. The statistical analysis indicated that there was no
significant difference between the treatments with respect to quality.
4.4.3 Refractive index
The refractive index of patchouli essential oil samples steam
distilled from shade dried herbage in the Pilot Scale Unit at different
packing bed densities and distillation times were between 1.5030 and
1.5055 (Table 4.3) which was similar to the BIS standard value specified
for patchouli oil (IS 3398 : 2003). There was no significant difference
between various treatments as far as the refractive index values of
essential oils distilled from them is concerned.
4.5 Comparison of Hydro and Steam Distillation Methods for Patchouli Essential Oil Yield and Quality
4.5.1 Essential oil yield
The yields of patchouli oil extracted from shade dried herbage by
two distillation techniques namely, hydro and steam distillation are
presented in Table 4.4. The shade dried patchouli herbage distilled in a
Pilot Scale Steam Distillation Unit (4 kg/0.5m3 packing bed density)
yielded 3.26% essential oil which was higher than the yield of essential
oil obtained in the laboratory (2.41%) by hydro-distillation technique
using Clevenger’s apparatus.
60
Table 4.3 Effect of bed packing density and distillation time on
refractive index of patchouli essential oil
NS - Not Significant
Bed packing density
(kg)
Refractive Index
Time of Distillation (h) Mean
3 4 5 6 4 1.5040 1.5035 1.5032 1.5035 1.5040
5 1.5030 1.5030 1.5040 1.5040 1.5039
6 1.5055 1.5045 1.5050 1.5050 1.5040
Mean 1.5033 1.5032 1.5045 1.5048
-
Distillation time
Bed packing
density
Interaction
SEM± CD @ 5% F value
0.0007 0.0020 NS
0.0006 0.0017 NS
0.0011 0.0035 NS
61
Table 4.4 Effect of type of distillation on the yield and quality of
essential oil
Parameter
BIS Standard
Values (IS 3398 : 2003)
Hydro Distillation
Steam Distillation
Oil Yield (%) - 2.41 3.26
Patchouli Alcohol Content (%) 27 - 35 64.65 42.89
Refractive Index 1.502 - 1.512 1.504 1.506
Optical Rotation ( ° ) -66 to -40 -47.1° -54.1°
62
4.5.2 Essential oil quality
The quality of patchouli essential oil extracted varied considerably
(Table 4.4) with the type of distillation technique employed. The BIS
standard for patchouli oil specifies that the patchouli alcohol content
should be in the range of 27-35% of the total composition. In the present
study, the patchouli alcohol content was 64.65% and 42.89%, the
refractive index of essential oils were 1.504 & 1.506 and optical rotation
of oils were -47.1° & -54.1° respectively in the essential oils distilled from
hydro-distillation technique (using Clevenger’s apparatus) and steam
distillation technique. Except for patchouli alcohol content, these values
were well within the range specified in BIS Code for patchouli oil for
patchouli oil. Higher patchouli alcohol content observed in the present
study is, however, a desirable trait for trade.
4.6 Cost Economics of Patchouli Oil Distillation
The cost economic analysis for extraction of essential oil from shade
dried patchouli herbage in the Pilot Scale Steam Distillation Plant is
presented in Appendix C. The total cost of distillation per batch (5 kg of
shade dried patchouli herbage) was worked out to be Rs. 429/- and the
net profit was calculated to be Rs. 144/- (26.5%). The cost: benefit ratio
of patchouli oil distillation was found to be 1: 1.26.
4.7 Variation in Major Constituents in the Patchouli Essential Oil
Distilled at Different Steam Distillation
The proportion of major constituents of patchouli essential oil
namely, patchouli alcohol, -guaiene, -bulnesene and β -patchoulene
were found to vary in the patchouli collected at different period of steam
distillation (1-3h, 3-4h, 4-5h) and the results are presented in Fig. 4.15,
4.16 and 4.17 for various packing bed densities of distillation.
63
0
5
10
15
20
25
30
35
(1-3) h (3-4) h (4-5) hDistillation Period
Con
tent
s (%
)
Patchouli Alcohol
Alpha-BulneseneAlpha-Guaiene
Beta-Patchoulene
Fig 4.17 Variation in patchouli oil quality at different distillation time intervals for packing bed density 6 kg/0.5m³
64
For 4kg/0.5m3 packaging bed density and at (1-3h), (3-4h) and (4-5h)
distillation periods the patchouli alcohol contents were – 25.15%, 36.18%
and 42.89%; -bulnesene contents were – 21.95%, 19.94% and 18.21%;
-guaiene content were – 16.14%, 12.33% and 9.77%; and β -
patchoulene content were - 0.0195%, 0.0171% and 0.0195%,
respectively.
It is clear from the data that the proportions of major constituents
varied significantly with the distillation period. It was interesting to note
that -guaiene distilled out faster at the beginning of distillation cycle
whereas the patchouli alcohol came out in higher quantities later. This
indicated that if distillation is for shorter period of time the resultant
patchouli essential oil will contain lesser amount of patchouli alcohol.
Similar, results were observed at 5kg/0.5m3 and 6kg/0.5m3 packaging
bed densities.
DISCUSSION
65
V DISCUSSION
The results of the experiments conducted during the course of
research study titled “Agro-Processing of Patchouli (Pogostemon cablin
Benth.) for Efficient Oil Extraction” are analyzed and discussed in this
chapter.
5.1 Drying Studies of Patchouli Herbage
The drying characteristics of fresh patchouli herbage dried at
different drying temperatures in a convective tray dryer are depicted in
Fig. 4.1 where as, the shade drying characteristics are given in Fig. 4.2
and drying characteristics in ASTRA Dryer are given in Fig.4.3.
5.1.1 Tray Drying Characteristics
In a tray dryer, the total drying time required to dry the freshly
harvested patchouli herbage from a moisture content of about 80% (wb)
to 10 – 11% (wb) was found to vary considerably depending upon the
temperature of drying. For 100 mm initial drying bed thickness, the
drying period required at 30, 40, 50, 60 and 70°C drying temperatures
were 13, 12, 11, 7 and 6 h, respectively which were much lower than the
shade drying time of 54 h. The influence of drying temperature on tray
drying time of patchouli was clearly discernible. Similar results were
reported by Raghavan et al. (1995) in drying fresh Indian thyme and
Chiumenti et al. (1996) in drying Salvia offinalis. The drying time reduced
considerably as drying temperature increased. For e.g., for 30°C, the
drying time was 13 h and for 70°C the drying time was 6 h only. Since,
the drying phenomena is a simultaneous heat and mass transfer
process, increase in drying temperature increased the drying potential
(i.e., temperature differential between product and drying air) which
helped faster drying of patchouli. Further, in a convective tray dryer, the
66
movement of relatively hotter drying air that carried the evaporated
moisture from th material also helped in improving the drying rate. The
moving drying air also aided the heat transfer process from the medium
to the drying material which is necessary for the vaporization of moisture
in the material. This is exactly the reason why the material dries faster in
a convective tray dryer than in an oven.
5.1.2 Shade Drying Characteristics
Under the moderate ambient conditions that prevailed in
Bangalore during shade drying, the fresh patchouli herbage required 54
h of drying time at 100 mm of initial drying bed thickness. Relatively
moderate ambient temperatures (21.0–24.4°C) and high relative humidity
(40-81%) that prevailed during shade drying prolonged the duration of
shade drying. Though this was similar to the duration of shade drying (2-
4 days) reported by Farooqui et al. (2001), the ambient conditions at the
time of their study and the final moisture content attained were not
reported for reasonable comparison.
5.1.3 Drying Characteristics in ASTRA Dryer
In ASTRA dryer, the total drying time required to dry the freshly
harvested patchouli herbage from a moisture content of about 80 to 10-
11% (wb) was found to be 14 h for 100 mm initial drying bed thickness.
Though the drying period required was only about 14 h as compared to
54 h of shade drying, it was higher than the drying times observed in
convective tray dryer. Since, the air movement inside this dryer must be
laminar (at low velocity) due to natural convection drying rate was
relatively slow. Further, inside the ASTRA dryer, the temperature varied
from 45-95°C at different levels that necessitated the shifting of trays
periodically from top to bottom position and vice versa. Further, the
drying air temperature control in this dryer was difficult and required lot
67
of skill since, it was done only by adjusting the rate of burning of fuel
(wood/briquettes). The dip in drying temperatures at the middle of
drying period in Fig. 4.4 was due to stoppage of dryer on the first day.
The drying was started when the dryer warmed up to 450C in the
following day. In the present study, the wood and briquettes are used as
fuel and the calorific value of wood and briquettes was 3500 kcal/kg.
Another disadvantage was elevated drying temperature of 95°C at the
bottom level may lead to the loss of volatile compounds present in the
patchouli oil in spite of this still the dryer is considered to be efficient for
drying patchouli herbage.
5.2 Effect of Drying of Herbage on Patchouli Essential Oil Yield
The quantities of essential oil extracted by hydro-distillation using
Clevenger’s apparatus from samples of patchouli dried under shade and
in the laboratory convectional tray dryer and in ASTRA Dryer are
presented in Fig. 4.5. It could be observed that the mean essential oil
yields were about 2.41% in shade dried sample, 2.25 – 2.40% in tray
dried samples and 2.24% in samples dried in ASTRA Dryer (Appendix –
A). Statistical analysis of data indicated that there was no significant
difference between various drying techniques with respect to essential oil
yield.
This study indicated that the fresh patchouli herbage can be dried
mechanically in a tray dryer without a loss in essential oil recovery. The
finding is really a boon for the farmers of some areas where the climatic
conditions are unfavorable for shade drying. This study also indicated
that the control of temperature was difficult in ASTRA dryer and heat
sensitive crops have to be carefully handled if this dryer has to be used
for them.
68
In the present drying study, the yields of patchouli essential oil, in
general, were comparable (2.25-2.41%) to the yield of around 2.5-2.98%
reported in the literature by Guenther (1948) and Farooqui et al. (2001).
Since, the leaves contain more patchouli oil of about 2.5 to 2.8%
compared to tender sticks (0.5%) (Farooqui and Sreeramu, 2001). The
ratio of dried patchouli leaves to tender sticks in this study was all along
maintained at 80:20 and therefore, the oil recovery was slightly less
compared to the reported results.
5.3 Effect of Drying of Herbage on Quality of Extracted Patchouli
Essential Oil
The patchouli alcohol content is the most important quality
attribute of the patchouli essential oil that is valued in commerce. The
patchouli alcohol contents of patchouli essential oils distilled from the
herbage dried under shade (64.65%) as well as in tray dryer at different
temperatures (57.15 to 66.26%) and in ASTRA dryer (42.27%) were
much higher than the value of 32-37% reported by Dung et al. (1990)
and the BIS specification for standard patchouli oil (27-35%). The
patchouli alcohol content, however, was slightly lower in the essential oil
distilled from dried herbage of ASTRA Dryer when compared to that from
the herbage dried in shade and tray dryer. Exact reason could not be
established in the present study. One possible reason might be that the
high temperatures of 90°C encountered at some levels of the ASTRA
Dryer during drying leads to the loss of patchouli alcohol content.
Further, the patchouli alcohol content of the oils obtained from the
herbage dried at drying temperatures of 30°C was slightly less when
compared to 40, 50, 60 and 70°C.
The effect of drying of patchouli herbage on the β-patchoulene
content of the extracted patchouli oil (from it) is depicted in Fig. 4.8. The
69
β-patchoulene content was considerably higher in the essential oil
distilled from the tray dried patchouli herbage at 70°C temperature
(0.0302 %) when compared to the values of 0.0277 , 0.0249 , 0.0206 and
0.0103 % respectively in the essential oils distilled from the patchouli
herbage tray dried at 60, 50, 40 and 30°C temperatures. The β-
patchoulene content of sample from the shade dried patchouli herbage is
comparable at 0.0249% and the least β-patchoulene content of 0.0076%
was noticed in samples from ASTRA Dryer. As it is known that these
aromatic compounds are sensitive to temperature, higher drying
temperatures might have resulted in degradation of β-patchoulene, -
guaiene and -bulnesene compounds. Chiumenti et al. (1996) observed
that the essential oil composition of Salvia officinalis was found to vary
slightly depending on drying temperature and the content of sensitive
compounds decreased with increased temperature, although the
contents of other compounds remained relatively constant.
Recent studies by Bure et al. (2004) have shown that patchouli
essential oil contains many more compounds, of which 41 of them were
separated and 28 of them (92.9% of total oil) were actually identified
using advance analysis techniques. The gas chromatographic analysis
(GC-FID) technique employed in the present study probably could not
explain the variation in quality aspects of patchouli oil exactly. Many
peaks that were detected in the chromatograph could not be associated
with known compounds. Therefore, it could be concluded that the oil
quality vis-à-vis the drying effect were only suggestive in nature
(probably sufficient for commerce) and further research may be
necessary in this area.
The refractive index values of the essential oil samples extracted
from different drying treatments did not vary significantly. The refractive
70
index values ranged between 1.501-1.505, which falls within the BIS
specifications (IS 3398:2003) for patchouli oil (1.502-1.512).
5.4 Pilot Scale Steam Distillation of Patchouli Essential Oil Pilot scale steam distillation of shade dried patchouli
herbage was carried out at 3 different packing bed density levels of 4, 5
and 6 kg/0.5m3 and the distillation times were also varied at 3, 4, 5 and
6 h to find out the essential oil yields and quality.
The effect of packing bed density and distillation time on patchouli
essential oil yield is presented in Fig.4.11 to 4.13. It could be observed
that the variation in packing bed density and distillation time had
significant influence on the essential oil yield.
At 4 kg/0.5m3 packing bed density, the patchouli essential oil
yields were 2.78, 3.06, 3.26 and 3.42 % respectively for 3, 4, 5 and 6 h
distillation time. At 5 kg/0.5m3 packing bed density, the patchouli
essential oil yields were 2.46, 2.74, 2.95 and 3.10% respectively for 3, 4,
5 and 6 h distillation time. Similarly, at 6 kg/0.5m3 packing bed density,
the patchouli essential oil yields were 2.25, 2.54, 2.79 and 2.97%
respectively for 3, 4, 5 and 6 h distillation time.
Further, from Fig. 4.14, it could be seen that the essential oil yield
was faster at the beginning of steam distillation i.e., up to first 3 h and
later on the oil yield was decreasing with time. Beyond 5 h of steam
distillation in the Pilot Scale Unit, very little oil was collected (at packing
bed density of 4 kg/0.5m3). Rao et al. (1999) reported field distillation
using steam at about 2 bar pressure in a 1000 kg capacity distillation
vessel. It took 120 min to what was considered a full extraction and
about 60 min to obtain 90% of the total oil extracted. Distillation tests
conducted by the method based on the determination of two parameters,
the “increment parameter” and the “basic time parameter” after
71
dimensioning of a still suitable for the processing of the plant could be
made (Denny, 1991).
5.5 Comparison of Steam and Hydro Distillation Methods
The yields of patchouli oil extracted from shade dried herbage by
two distillation techniques namely, hydro and steam distillation are
presented in Table 4.4. The shade dried patchouli herbage distilled in a
Pilot Scale Steam Distillation Unit (4 kg/0.5m3 packing bed density)
yielded 3.26% essential oil which was higher than the yield of essential
oil obtained in the laboratory (2.41%) by hydro-distillation technique
using Clevenger’s apparatus.
Similar results were obtained by Guenther (1948) for patchouli and
Denys et al. (1990) for Basil. Guenther (1948) reported that patchouli
yielded 3.27 % essential oil on steam distillation and only 2.98 % on
hydro-distillation. It was also reported that steam distillation in certain
plant materials has been found to increase the total yield of essential oil.
Denys et al. (1990) noticed that the yield of essential oil of Basil was
consistently higher from steam distillation than hydro-distillation. The
essential oil yield in hydro-distillation was generally less due to the fact
that some of the high boiling constituents of patchouli essential oil that
are partly soluble in water might not distill out completely as vapours
(Prasad et al. 1987). Where as in steam distillation, the temperature of
distillation was slightly higher than hydro-distillation and that helped
better extraction of available oil in the material.
5.6 Cost Economics of Patchouli Oil Distillation
The cost economic analysis worked out for the pilot scale steam
distillation of shade dried patchouli herbage showed that the net profit
for patchouli steam distillation was 26.50%. This works out to be
72
economical (cost : benefit ratio – 1:1.26) for the farmers who grow
patchouli and wish to distill the essential oil.
5.7 Variation in Major Constituents in the Patchouli Essential Oil Distilled at Different Steam Distillation
The proportion of major constituents of patchouli essential oil
namely, patchouli alcohol, -guaiene, -bulnesene and β-patchoulene
were found to vary in the patchouli collected at different period of steam
distillation (1-3h, 3-4h, 4-5h) and the results are presented in Fig. 4.15,
4.16 and 4.17 for various packaging bed densities of distillation.
For 4kg/0.5m3 packaging bed density and at (1-3h), (3-4h) and (4-
5h) distillation periods the patchouli alcohol contents were – 25.15,
36.18and 42.89%; -bulnesene contents were – 21.95, 19.94 and
18.21%; -guaiene content were – 16.14, 12.33 and 9.77%; and β-
patchoulene content were - 0.0195, 0.0171 and 0.0195%, respectively.
It is clear from the data that the proportions of major constituents
varied significantly with the distillation period. It was interesting to note
that -guaiene distilled out faster at the beginning of distillation cycle
whereas the patchouli alcohol came out in higher quantities later. This
indicated that if distillation is for shorter period of time the resultant
patchouli essential oil will contain lesser amount of patchouli alcohol.
Similar, results were observed at 5kg/0.5m3 and 6kg/0.5m3 packaging
bed densities.
SUMMARY
73
VI SUMMARY
Patchouli is an important aromatic herb grown for its essential oil.
Patchouli oil is found mainly in the dried leaves and a small quantity of
oil is also present in the tender parts of the stem. Due to its good fixative
properties, patchouli oil is a key constituent in exotic perfumes especially
in soap perfumes. Post harvest handling of the patchouli herbage play an
important role in obtaining the patchouli essential oil both in terms of oil
yield and quality. The present extraction efficiency of this high valued oil
is only about 2 – 2.8% (available 3 – 3.5%) probably due to improper post
harvest handling practices at various stages like herbage drying,
distillation, etc. Therefore, this study on “Agro-Processing of Patchouli
(Pogostemon cablin Benth.) for Efficient Oil Extraction” was undertaken to
study and standardize the initial raw material handling and drying
practices of patchouli for improved distillation efficiency and also to
study essential oil yield and quality.
To study the drying characteristics of patchouli, fresh herbage (cv.
Johore) was dried under shade, in ASTRA dryer as well as in a
convectional Tray Dryer at 30, 40, 50, 60 and 70°C temperatures and the
initial drying bed thickness was uniformly maintained at 100 mm. The
effects of drying methods on the patchouli essential oil yield and its
quality were studied using Clevenger’s Essential Oil Distillation Unit and
Gas Chromatograph. Patchouli oil was also extracted from shade dried
patchouli herbage using a Pilot Scale Steam Distillation Unit at different
packing bed densities and distillation times. Further, a comparative
study was made between hydro distillation of patchouli using
Clevenger’s Unit and steam distillation using Pilot Scale Steam
Distillation Unit in terms of essential oil yield and quality.
74
From the results obtained from the above studies, the following
important conclusions could be drawn:
1. Under the moderate ambient conditions of temperature (21.0–
24.4°C) and relative humidity (40-81%) that prevailed at Bangalore
during shade drying, the fresh patchouli herbage required about 54 h
of drying time (for 100 mm of initial drying bed thicknesses) to dry it
from an initial moisture content of 80 % (wb) to a final moisture
content of 11-12% (wb).
2. For drying patchouli herbage, in a tray dryer, the drying period
required at 30, 40, 50, 60 and 700C drying temperatures were 13, 12,
11, 7 and 6 h, respectively for 100 mm initial drying bed depth.
3. The fresh patchouli herbage required about 14 h to dry from an
initial moisture content of 80 %(wb) to a final moisture content of 11-
12 %(wb)in ASTRA Dryer.
4. The mean essential oil yields were about 2.41% in shade dried
sample, 2.25 – 2.40% in tray dried samples and 2.24% in samples
dried in ASTRA Dryer. Statistical analysis of data indicated that there
was no significant difference between various drying techniques with
respect to essential oil yield.
5. There was a considerable variation in the quality of patchouli oil
extracted from herbage dried at different drying temperatures.
Patchouli alcohol content in the essential oil was highest (66.26%) in
the oil distilled from the herbage dried at 70°C in a tray dryer and it
was least (42.27%) in the oil distilled from the herbage dried ASTRA
Dryer. The sample from shade dried herbage was found to contain
64.65% patchouli alcohol content and it was observed to be 64.54%,
75
64.19%, 63.87% and 57.15% in the other patchouli oil samples
distilled from the herbage dried respectively at 50, 40, 60 and 30°C in
convectional tray dryer. The composition of -guaiene and -
bulnesene in the patchouli essential oil were higher in the oil distilled
from Astra dried herbage. The compositions of β-patchoulene in the
patchouli essential oil were higher in the oil distilled from the herbage
dried at 70°C in a tray dryer.
6. The refractive index of patchouli oil samples distilled from patchouli
herbage dried under shade, ASTRA dryer as well as in tray dryer at
different drying temperatures varied from 1.504 to 1.506.
7. The notion that shade drying will yield better oil with better quality
has been disproved. The patchouli herbage dried mechanically yielded
the same quantity of oil with premium quality attributes as that of
shade dried herbage.
8. Patchouli essential oil yields from steam distillation of shade dried
patchouli herbage in a Pilot Scale Steam Distillation Plant at different
bed densities and at different distillation times were as follows : At 4
kg/0.5m3 packing bed density, the patchouli essential oil yields were
2.78, 3.06, 3.26 and 3.42 % respectively for 3, 4, 5 and 6 h distillation
time; At 5 kg/0.5m3 packing bed density, the patchouli essential oil
yields were 2.46, 2.74, 2.95 and 3.10% respectively for 3, 4, 5 and 6 h
distillation time; and at 6 kg/0.5m3 packing bed density, the
patchouli essential oil yields were 2.25, 2.54, 2.79 and 2.97%
respectively for 3, 4, 5 and 6 h distillation time.
9. Patchouli essential oil quality from steam distillation of shade dried
patchouli herbage in a Pilot Scale Steam Distillation Plant at different
bed densities and at different distillation times were as follows:
Patchouli alcohol content varied from 34.74% in 4 kg/0.5m³, 34.92%
76
in 5 kg/0.5m³, and 27.78% in 6 kg/0.5m³; α-Bulnesene content
varied from 20.04% in 4 kg/0.5m³, 19.75% in 5 kg/0.5m³, and
19.38% in 6 kg/0.5m³; α- Guaiene content varied from 12.75% in 4
kg/0.5m³, 12.71% in 5 kg/0.5m³, and 19.38% in 6 kg/0.5m³; and β-
Patchoulene varied from 0.0187% in 4 kg/0.5m³, 0.0165% in 5
kg/0.5m³, and 0.000% in 6 kg/0.5m³ for different samples of
essential oils.
10. The shade dried patchouli herbage distilled in a Pilot Scale Steam
Distillation Unit (4 kg/0.5m3 packing bed density) yielded 3.26%
essential oil which was higher than the yield of essential oil obtained
in the laboratory (2.41%) by hydro distillation technique using
Clevenger’s apparatus.
11. The patchouli alcohol content was 64.65% and 42.89%, the
refractive index of essential oils were 1.504 & 1.506 and optical
rotation of oils were -47.1° & -54.1° respectively in the essential oils
distilled from hydro-distillation technique (using Clevenger’s
apparatus) and steam distillation technique. Expect for patchouli
alcohol content, these values were well within the range specified in
BIS Code for patchouli oil. Higher patchouli alcohol content observed
in the present study is, however, a desirable trait for trade.
12. Cost economic analysis of patchouli essential oil using Pilot Scale
Steam Distillation Unit indicated that the extraction is viable and the
cost: benefit ratio of patchouli oil distillation was found to be 1: 1.26.
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77
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APPENDIX
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Appendix - A
Effect of drying temperature of patchouli herbage on patchouli
essential oil yield under different drying methods
Temperature
(°C) R1 R2
R3
Mean essential oil yield (%)
30
2.39 2.40 2.41 2.40
40 2.28 2.29 2.33 2.30
50 2.31 2.31 2.34 2.32
60 2.27 2.31 2.29 2.29
70 2.27 2.23 2.25 2.25
Shade
2.37 2.43 2.43 2.41
Astra 2.21 2.25 2.26 2.24
F- Test NS NS NS NS
CD - - - -
NS – Not Significant
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Appendix –B
Effect of bed packing density and distillation time on patchouli
essential oil yield
*- Significant at 5%
Packing bed density (kg)
Essential Oil Yield (%)
Distillation Time (h) Mean
3 4 5 6
4 2.78 3.06 3.26 3.42 2.92
5 2.46 2.74 2.95 3.10 2.85
6 2.25 2.54 2.79 2.9 7 2.80
Distillation Time Mean 3.03 2.87 2.77 2.77
-
1) Packing bed density 2)Distillation time 3)Interaction
SEM± CD @ F value 5% 0.0214 0.0625 * 0.0247 0.0722 * 0.0428 0.125 *
88
Appendix - C
Cost Economics of Pilot Scale Steam Distillation of Patchouli Oil
1. Fixed cost:
Capital cost of distillation unit = Rs. 55,000/-
Expected life = 10 years
Expected operational hours of
distillation unit / year = 300 distillations x 6 h
= 1800 h
a) Depreciation = 55,000 - 5500 1800 X 10 = Rs. 2.75/h
b) Interest on capital
investment @ 12% = (55000 + 5500)/2 X
(12/100) X (1/1800)
= Rs. 2.02/h
c) Insurance and maintenance cost
at 5% of machinery cost per year = (5/100) X 55000 X 1/1800
= Rs. 1.52/h
Total Fixed Cost = Rs. 2.75 + 2.016 + 1.527
= Rs. 6.30/h
2. Variable cost:
a) Power consumption = 1 Unit/h
Energy cost @ Rs. 3.20/unit = Rs. 3.20/h
b) Labour cost @ Rs. 60/day of 6 h work = 1 X Rs. 60 X 1/6
= Rs. 10/h
c) Herbage required = 5 kg dry herbage
89
Herbage cost @ Rs. 52/kg dry herbage = Rs. 52/h
Total Variable Cost = Rs. 3.20 + 10 + 52
= Rs. 65.20/h
Total cost of distillation = Fixed cost + Variable cost
= Rs. 6.30+ Rs.65.20
= Rs. 71.5/h
Total cost of distillation/batch = Rs. 71.5 X 6
= Rs. 429/batch
Essential oil yield per distillation at 3.10% yield = 155 ml
Market price of patchouli oil per liter = Rs. 3500/-
Revenue = 155/1000 X 3500
= Rs. 543/- per batch
Net return per batch = Revenue – Total Cost
= Rs. 543 – Rs. 429
= Rs. 114/-
Net annual returns = Rs. 144 X 300
= Rs. 34,200/-
Profit (%) = (114/429) X 100
= 26.5%
Cost Benefit Ratio = 429: 543
= 1: 1.26