Embed Size (px)
Citation preview
DSpace Institution
DSpace Repository http://dspace.org
Food technology thesis
2020-03-11
PHYSICO-CHEMICAL
CHARACTERIZATION OF SOME
MANGO VARIETY GROWN IN
ETHIOPIAN FOR JAM SUITABILIT
Bekele, Melkam
http://hdl.handle.net/123456789/10197
Downloaded from DSpace Repository, DSpace Institution's institutional repository
BAHIR DAR UNIVERSITY
BAHIR DAR INSTITUTE OF TECHNOLOGY
SCHOOL OF RESEARCH AND POSTGRADUATE STUDIES
FACULTY OF CHEMICAL AND FOOD ENGINEERING
PHYSICO-CHEMICAL CHARACTERIZATION OF SOME MANGO
VARIETY GROWN IN ETHIOPIAN FOR JAM SUITABILITY
By
MELKAM BEKELE
BAHIR DAR, ETHIOPIA
JULY 2019
PHYSICO-CHEMICAL CHARACTERIZATION OF SOME MANGO
VARIETY GROWN IN ETHIOPIAN FOR JAM SUITABILITY
Melkam Bekele
A Thesis
Submitted to Faculty of Chemical and Food Engineering, Bahir Dar
Institute of Technology, Bahir Dar University in partial fulfillment of the
requirements for the Degree of Master of Science in Food Technology
Advisor: Dr. Neela Satheesh
Co-Advisor: Sadik Jemal
Bahir Dar, Ethiopia
May 2019
I
DECLARATION
II
©2019
Melkam Bekele
ALL RIGHT RESERVED
III
IV
To my beloved husband
V
ACKNOWLEDGEMENT
My special thanks to almighty God for his love, support and provision throughout this
work. I would like to express my sincere thanks to my Advisors Dr. Neela Satheesh,
Associate professor and Co-Advisor Sadik Jemal, Assistant professor for their expert
guidance, timely response, encouragement and valuable suggestion which were
provided throughout the research. I would like to thank Adet Agricultural Research
Institute for providing raw material and Bahir Dar University for allowing me to use
laboratories and related equipments.
My special thanks should be equally given to my mother W/o Fanaye Talema, my father
Ato Bekele Delessa, my husband Ato Addisu Damena and all my family members and
also for Dr. Chanukya B. S, Ato Agumase Agize, W/ro Fitfite Melese, Lemlem Seyum,
Jemanesh Abol, Ato Chala Goew, Jimma College of Agriculture and veterinary
medicine, for their continuous support and encouragement.
VI
ABSTRACT
Mango is seasonal and perishable product, due to its perishability huge losses are
reported in Ethiopia. Due to this it seems vital to find an alternative method to
effectively reduce the post harvest loss. Processing of mango fruit in to jam is one
method to effectively use perishable mango in to stable product. Initially, in this study
the physico-chemical properties of six mango cultivar namely Tommy, Kent, Keitt,
Dodo, Local and Apple on their suitability for jam production were investigated.
“ANOVA showed that there was significant difference in physico- chemical properties
among the six cultivars of mango”, Apple mango variety was selected according to the
standard requirements for jam preparation. In the second study, Apple mango jam
formulations produced using three factor full factorial design with pH in two levels (3
and 3.3) pectin in three levels (0,1,and 1.5%) and sugar in two levels (50 and 60%) were
evaluated. The prepared jam was analyzed to determine the effect of different
parameters on physico-chemical properties. The statistical analysis of data was carried
out using Minitab 18.1 software. According to the results of fruit physicochemical
analysis Apple mango cultivar has TSS (17.06 %), TS (15.57%), MC (71.30%), AC
(0.36%), RS (2.63%), pH (3.33) and TA (0.27mg/100 g) value,
which makes it more suitable than other cultivar for jam preparation. All of the three
factors were an important factor which affects the nutrient quality as well as sensory
acceptability of mango jam. Processing of mango fruit pulp in to jam resulted in
significant increase in total soluble solid and titratable acidity but a significant decrease
in vitamin C and moisture content. Out of 12 samples of mango jam sample formulated
with different ratio, jam with pectin (1.5%), sugar (60%) and pH (3.3) was found to be
high in vitamin C content and TS and also more acceptable in appearance, flavor,
consistency, color and overall acceptability by the sensory panelists. In general, there
was a clear difference between mango cultivar on their potential for jam processing.
The quality of the jam is highly dependent on the choice of concentrations of each
ingredient and the four main ingredients in jam preparation are fruit type, sugar (S),
pectin (P) and citric acid. Finding out the right combination of these ingredients resulted
in more acceptable jam with better physico-chemical quality.
Key words: Acidity, Jam, Mango, pectin, Sugar
VII
TABLE OF CONTENTS
DECLARATION .......................................................................................................... I
ACKNOWLEDGEMENT .......................................................................................... V
ABSTRACT ............................................................................................................... VI
TABLE OF CONTENTS ......................................................................................... VII
LIST OF ABBREVIATIONS .................................................................................... IX
LIST OF SYMBOLS .................................................................................................. X
LIST OF FIGURES ................................................................................................... XI
LIST OF TABLES ................................................................................................... XII
1 INTRODUCTION .................................................................................................... 1
1.1 Background ....................................................................................................... 1
1.2 Statement of the Problem .................................................................................. 2
1.3 Objective of the study ........................................................................................ 4
1.4 Scope of the research ......................................................................................... 4
1.5 Significance of the research............................................................................... 4
2 LITERATURE REVIEW ......................................................................................... 5
2.1 Introduction, botany and importance ................................................................. 5
2.2 Mango cultivar grown in Ethiopia .................................................................... 5
2.2.1 Tommy Atkins ............................................................................................. 5
2.2.2 Kent ............................................................................................................. 6
2.2.3 Keitt ............................................................................................................. 6
2.2.4 Apple mango ............................................................................................... 6
2.2.5 Dodo mango ................................................................................................ 6
2.3 Post harvest loss ................................................................................................ 7
2.3.1 Post harvest loss of fruits in Ethiopia .......................................................... 7
2.3.2 Post harvest value addition .......................................................................... 8
2.3.3 Mango chemical properties ......................................................................... 8
2.3.4 Nutritional properties and value of mango .................................................. 8
2.3.5 Processed Mango products .......................................................................... 9
2.4 Jam production ................................................................................................ 11
2.4.1 Ingredients for jam .................................................................................... 12
2.4.2 Method of manufacturing jam ................................................................... 14
2.4.3 Quality standards for jam .......................................................................... 16
3 MATERIALS AND METHODS ............................................................................ 19
3.1 Experimental Material ..................................................................................... 19
3.2 Experimental description ................................................................................. 20
3.2.1 Study 1: Characterization of mango for jam suitability ............................ 20
3.2.2 Study 2: Jam formulation and physico-chemical analysis......................... 20
3.2.3 Methods of jam making ............................................................................. 20
3.3 Experimental design ........................................................................................ 21
3.4 Physico-Chemical characterization of mango variety ..................................... 22
3.4.1 Determination of pulp percentage ............................................................. 22
3.4.2 Determination of Total Soluble Solids (TSS) ........................................... 22
VIII
3.4.3 Determination of moisture content ............................................................ 22
3.4.4 Determination of ash content .................................................................... 23 3.4.5 Determination of pH .................................................................................. 23
3.4.6 Determination of Total Titratable Acidity (TTA) ..................................... 24
3.4.7 Determination of Total sugar .................................................................... 24
3.4.8 Reducing sugars: ....................................................................................... 25
3.4.9 Determination of Vitamin C content ......................................................... 25
3.5 Sensory analysis of the final jam ..................................................................... 26
3.6 Statistical analysis ........................................................................................... 27
4 RESULTS AND DISCUSSION ............................................................................. 28
4.1 Physico-chemical properties of the mango cultivars ....................................... 28
4.1.1 Juice percentage ........................................................................................ 30
4.1.2 Moisture content ........................................................................................ 30
4.1.3 Ash content ................................................................................................ 31
4.1.4 pH .............................................................................................................. 31 4.1.5 Titratable Acidity ...................................................................................... 31
4.1.6 Total soluble solids .................................................................................... 32
4.1.7 Total sugar ................................................................................................. 33
4.1.8 Reducing sugars......................................................................................... 33
4.2 Physico-chemical properties of mango jam .................................................... 34
4.2.1 Moisture content ........................................................................................ 36
4.2.2 Ash content ................................................................................................ 36
4.2.3 Titratable acidity ........................................................................................ 36
4.2.4 Total sugar ................................................................................................. 37
4.2.5 Reducing sugar .......................................................................................... 37
4.2.6 Vitamin C .................................................................................................. 38
4.3 Sensory analysis of mango jam ....................................................................... 39
4.3.1 Appearance ................................................................................................ 40
4.3.2 Flavor ......................................................................................................... 41 4.3.3 Consistency ............................................................................................... 41
4.3.4 Color .......................................................................................................... 42
4.3.5 Overall acceptance .................................................................................... 42
5 CONCLUSION AND RECOMMENDATION ...................................................... 43
5.1 Summery ......................................................................................................... 43 5.2 Conclusions ..................................................................................................... 43
5.3 Recommendations ........................................................................................... 44
REFERENCES .......................................................................................................... 45
APPENDIX ................................................................................................................ 53
Appendix A: Physicochemical analysis ANOVA result mango fruit ........................ 53
Appendix B: Physicochemical analysis ANOVA result mango jam ......................... 57
Appendix C: Sensory evaluation of mango jam ........................................................ 61
Appendix D: Questioner for Sensory Testing ............................................................ 64
Appendix E: Picture during research work ................................................................ 65
IX
LIST OF ABBREVIATIONS
AC Ash content
AOAC Association of analytical chemists
ANOVA Analysis of variance
BDU Bahir Dar University
BiT Bahir Dar Institute of Technology
CRD Complete randomized design
MC Moisture content
SAS Statistical Analysis Software
TA Titratable Acidity
TS Total Sugar
TSS Total Soluble solid Content
WHO World Health Organization
FAO Food and Agriculture Organization
CAC Codex Alimentarius Commission
FPO Follow on Public Officer
SNNPR Southern Nations, Nationalities, and Peoples’ Region
X
LIST OF SYMBOLS
g Gram
mg Milligram
ml milliliter
Qt Quintal
B/ Qt Birr per quintal
ETB Ethiopian birr
XI
LIST OF FIGURES
Figure 1. The mango cultivar used in this study .......................................................19
Figure 2. Flow diagram for mango jams production ...............................................21
XII
LIST OF TABLES
Table 1. Production and post harvest loss of selected fruit and vegetables in Ethiopia
.....................................................................................................................................7
Table 2 Average Nutritional content per 100g of raw mango pulp ............................9
Table 3. FPO Specifications of Jams and Jellies ......................................................17
Table 4. Full factorial design table with different factors and levels for jam
preparation ................................................................................................................22
Table 5.The physico-chemical properties of mango cultivars ..................................29
Table 6:Apple mango chemical composition............................................................34
Table 7. The physicochemical properties of mango jam ..........................................35
Table 8. Sensory evaluation of mango jam ...............................................................40
1
1 INTRODUCTION
1.1 Background
Mango is being cultivated in many tropical and subtropical regions and is distributed in
worldwide. The genus Mangifera belongs to the family ‘Anacardiaceae’. Mango
(Mangifera indica L.) is one of the most well-liked fruit for its rich nutritional profile
with a distinctive flavor, fragrance, taste, color and texture. Mango is an excellent
source of vitamin A and C and is rich in carbohydrates, minerals (potassium,
phosphorus), phenolic compounds and dietary antioxidants(FAO 2002). Its yellow-
orange characteristic color is attributed to the presence of carotenoids (Venkateswarlu
and Reddy 2014). Deficiency of Vitamin A has been known as major health problem
especially in Africa and South-East Asia(WHO 2006). The major risk groups for
Vitamin A deficiency are children and pregnant women. The intake of fruits like mango
is suggested to overcome vitamin A deficiency. Dietary carotenoids are considered to
be valuable in the prevention of a variety of major diseases, including certain cancers
and eye diseases (Krinsky, Norman and Johnson 2005).
Mangoes are seasonal fruits and ripen quite rapidly after harvest; the strict perishable
nature of the fruit limits the transportation of fresh fruits from the site of the harvest to
distance places. The marketability of this perishable fruit is closely linked with the
development of postharvest value addition technologies which reduce the loss at
different stages of harvesting and storage conditions (Khairul et al. 2013).
Processing of fruit is considered as improving the value of raw produce and an
extension of storage life (Okoth et al. 2013). Mango fruits can be processed into various
products: unripe mangoes are normally processed into powders, pickles, preserves,
dessert or chutneys while the ripe mangoes can be processed into dried mango chips,
mango wine, mango juice, concentrate, jam, jelly, syrup and canned mango (Musyimi
2013). The suitability of mango fruit for the processing depends on the physico-
chemical characteristics, which are dependent upon the mango cultivar. Selection of
specific variety is appropriate for the processing of fruit in to value added product.
2
In Ethiopia, there are only few fruit processing companies. The most known fruits and
vegetables processing plants produce vegetable soups, orange marmalade, tomato paste
and wine, but the use of mango in to these products are very limited. In order to reduce
post harvest losses and expand the processing industry researches on development of
different value added products and introduction of applicable technology is necessary
(Wiersinga and Jager 2007).
Jam preparation is the best suited technique for perishable fruits preservation. It is an
ancient method of preservation and is used in many parts of the world. Jam is a fruit
solid gel made from the pulp of a single fruit or mixed fruits by boiling the fruit pulp
with sugar (sucrose), pectin, acid and other ingredients (preservative, coloring, limited
amount of fruit peels and flavoring materials). Jams should be in a reasonable thick
consistency that is firm enough to hold the fruit tissues in position (Shanmugam,
Rangaswami, and Gurney 1992). In production of jam the minimum fruit content ought
to be 40% and the expected total soluble solid content is not less than 68% (Featherstone
2016) .Jams are rich in sugar and are great source of energy, fiber, life- sustaining
vitamins, minerals and amino acids. Therefore, consumption of jam also lowers the
chances of getting heart attack and cardiovascular ailments, along with healthy weight
(Lunagrown 2018).
1.2 Statement of the Problem
Agriculture is backbone of Ethiopian economy with about 86% of the population is
engaged in agricultural practice. The environmental conditions, good fertile lands
availability for cultivation and relatively cheap labor, high human resource makes the
country more suitable for the production of cultivar of fruit and vegetables. The total
production of fresh mango in Ethiopia is about 72.187 tons in year 2013/2014 (CSA.
2014). Even though there is high production, the capability of the country has not been
fully explored yet. The market demand for quantity and quality of mango is also not
sufficiently met.
The major factors influencing the appropriate production of mango in Ethiopia are the
lack of knowledge about the production, harvesting and post harvest handling of fruit
along with the limitation of skills and facilities (Honja 2014).
3
During mango harvesting season there is high post-harvest loss (43.53%) reported
(Kasso and Bekele 2016). This leads supplying the fruits to only local markets and
exporting of fruit products is dropping from time to time. Mango was exported
previously by Et-fruit to Djibouti, Saudi Arabia and UAE. However, it has lost contract
because of the variability of the quality of product, since the opportunities in export
market mainly focus on the quality of products. Ethiopia’s fruit productions and exports
play a significant role in the local economy as a means of earning livelihoods by
creating jobs and generating foreign exchange revenues (Honja 2014).
Processing of fruit is an important step for preservation of seasonal gluts and for
survival in shortage along with availability of different foods throughout the year.
Processing also extends the shelf life of products. In many countries, fruit harvesting is
still based on seasons, and so usually a particular fruit is consumed at 1 or 2 seasons in
year. By preserving the fruit as jams and juices customers can enjoy these fruits all
round the year outside of harvest time. Similarly, producers will fetch a much better
price than the raw fruit.
In Ethiopia mango processing industries are few in number in contrast sizeable amount
of fruit produced in each season. The study regarding the suitability of mango cultivar
for jam production and effect of different components (acidity, sugar concentration and
pectin concentrations) on jam quality are hardly found. By considering all the stated
gaps, this study was conducted to explore the potential of six mango cultivar for jam
production as well as to characterize and evaluate sensory quality of prepared mango
jam from a best variety. Research on the production of value-added products like mango
jam is important to increase extra income generation. It creates new investment and
employment opportunities for local small- scale industries.
Still, the scientific reports on the characterization of mango variety suitability and pH,
pectin, sugar levels on the jam quality are limited in Ethiopian. So, this study was
carried out with following objectives.
4
1.3 Objective of the study
General objective
• To screen for best variety of mango for Jam making among varieties grown in
Ethiopia and optimize pH, sugar and pectin levels”
Specific objectives
• To determine the physico-chemical properties of six mango cultivar (Keitt,
Kent, Apple, Dodo, Tommy and Local(mango variety specifically grown in
Merawi, Amhara region Ethiopia) to screen their suitability for jam preparation
• To determine the effect of different levels of sugar, pH and Pectin on different
physico-chemical and sensory properties of jam
1.4 Scope of the research
This thesis work focuses on characterization of mango varieties grown in Ethiopia,
preparation of mango jam and determining the effect of sugar, pectin and pH level on
physicochemical and sensory properties of mango jam.
1.5 Significance of the research
The study is believed to be significant in reduction of post harvest loss of mango fruit
in Ethiopia by developing a shelf stable product, mango jam. The research provides
important information about the chemical properties of different mango cultivars for
fruit processing industries, agricultural sectors and fruit exporters. It can be an initial
point to support export market for raw and processed products, increase availability of
mango product throughout the year by developing mango jam, creates new investment
and employment opportunity. In all this incubation of fruit jam processing is important
for saving foreign currency and increasing extra income generation.
5
2 LITERATURE REVIEW
2.1 Introduction, botany and importance
Mango is one of the major tropical fruit and considered to be among one of the most
consumed fresh fruits in the world. The name Mangifera is derived from the word
Mangai (the Tamil name for mango) and fero (meaning to bear). The word indica
means Indian and stands for the name of the species. The wild races of Mangifera
indica bear fruits with scanty, slimy flesh, having a fine aroma, and almost free of fibers
(Subramanyam, Krishnamurthy, and Parpia 2000). Mango is a unique fruit in terms of
the diverse products processed from it, especially from its immature to fully- ripe
stages. The most common processed mango products are puree/pulp, nectar, juice, juice
concentrate, and dried/dehydrated mangoes. Besides these common products, there are
a number of traditional products which are processed commercially in major mango
producing countries, such as pickles, sweet or sour chutney, mango leather, and a
variety of soft drinks and beverages (Siddiq et al.2012).
2.2 Mango cultivar grown in Ethiopia
There are thousands of mango cultivar in the world. A common variety worldwide is
“Tommy Atkins” and is also grown in Ethiopia (Yeshitela, T., Robbertse, P. J. & Stassen
2005). Other cultivar grown in Ethiopia includes Kent, Keitt, Dodo and Apple mango
(figure 1)(IPMS 2011). Some cultivar of mango are discussed below:
2.2.1 Tommy Atkins
Tommy Atkins is mostly known commercial mango variety. The size of the fruit varies
from medium to large (450 to 700 g), and it is in oval shape, with a rounded apex. They
measure an average length of 12.6 cm, 9.9 cm wide and they have orange to yellow
color with a heavy red blush. The flesh is firm and medium juicy with a moderate
amount of fiber. It is an early to mid-season cultivar and is highly resistant to diseases
and productive. The fiber content of Tommy mango variety is slightly higher than
average which make it less favorable for jam production (Griesbach 2003).
6
2.2.2 Kent
Kent is a sweet, juicy and tender mango variety with an excellent eating quality with
little fiber. The fruit is large greenish-yellow with a red or crimson blush on the
shoulder. The average length measures 12.4 cm with a width of 9.7 cm and a Floridian
variety of Kent weight up to 800 g, with an average weight of 545 g. The fruit-shape is
regular ovate with a rounded base and often with two slight beaks. The skin is thick and
tough and small yellow lenticels are numerous. It is produced in most Latin American
and African exporter countries. Kent mango is suitable for shipment since it late
maturity (Griesbach 2003).
2.2.3 Keitt
Keitt mango flesh is firm, juicy and has good taste. It also has only a little fiber near the
seed. It is rich in flavor and sweet with a pleasant aroma and excellent quality. The fruit
is large with an average weight of 456 g, length of 11.7 cm and a width of 9.2cm. It has
a greenish-yellow color with pink or red blush and lavender bloom. There are numerous
white or yellow/red lenticels on the thick and fairly tough skin. The fruit shape is ovate
and plump without a beak with round base. It has good marketing qualities and
productivity(UNCTAD 2016) .
2.2.4 Apple mango
Apple is the best mango variety for jam production because of the juicy yellow flesh
with outstanding flavor and soft texture virtually free from fiber. The size of the fruits
are medium to large with an average weight of 397 g and average length of 9.7 cm by
11 cm in width and the seed size is small. It is nearly round in shape and turn to a rich
yellow/orange to red color when ripen. Depending on location, harvesting seasons are
from December to the beginning of March and the yields are medium (Griesbach 2003).
2.2.5 Dodo mango
The fruit is large and fairly oval and ripens from dark green to a light green and finally
turns to yellow color. The flesh is in orange color and juicy, the fiber content varies
from little to more and there is usually a strong turpentine flavor. Lenticels are
7
plenty, first appears in green and later changing to brownish in ripening process. The
average dimensions are: length 11.6 cm by 9.9 cm in width, weight 453 g (range: 339-
500 g). This fruits usually mature in January and February and shows a very good
resistance to anthracnose and also travels well to the market (Griesbach 2003).
2.3 Post harvest loss
2.3.1 Post harvest loss of fruits in Ethiopia
Like other tropical fruits, mango is seasonal, with relatively short postharvest shelf life.
Post-harvest losses can be measured by qualitative and quantitative losses of the
product. Post harvest loss can occur during different activities at harvesting time, during
transportation of the fruit to longer distance travel with poor infrastructure, packing and
also during storage(Hodges, Bubzby, and Bennett 2011). This post harvest handling
problem create a remarkable physical (mechanical injury), physiological (wilting,
shriveling and chilling injury, etc) and pathological (decay due to fungi and bacteria)
damages on the fruit (Kader 2010). The magnitude of post- harvest loss of horticultural
crops was found higher and reported as mango (43.53%), banana (20-40%), cabbage
(58.9%), tomato (45.32%), avocado (≥ 23%), papaya (≥ 29.2%), coffee (15.75%)
(Gebremeskel 2018). The production and post harvest loss of some fruit and vegetables
in Ethiopia (2015/2016)are shown in the Table 1: (Kasso and Bekele 2016).
Table 1. Production and post harvest loss of selected fruit and vegetables in Ethiopia
Crop
Total
Production
(Qt)
Post
harves
t loss
Amount Lost
(Qt)
Unit
Price(ET
B/qt)
Monetary Value
(ETB)
(%)
Potato 36,576,382.69 37.15 13,588,126.17 1,000.77 13,598,589,026.49
Tomato 12,581,433.98 45.32 5,701,905.88 1,300.17 7,413,446,967.66
Mango 1,000,514.90 43.53 436,730.04 2,700.39 1,179,611,460.83
Avocado 538,245.79 40.00 215,298.32 2,000.00 430,596,632.00
Banana 4,401,344.16 45.78 2,014,935.36 2,1003.64 4,232,653,807.17
Total 55,100,921.52 21,957,095.76 26,854,897.14
8
Source: Calculated from CSA Ethiopia (2016)
2.3.2 Post harvest value addition
Post harvest value addition is a process which includes primary, secondary and tertiary
processing operations performed on farm produce. Fruits are highly perishable and
seasonal items which can easily loss their quality and nutrient value. For example
Mango shelf life is only 2 to 4 weeks at 10°C to 15°C this limit availability of fresh
mango in the market (Cisneros-Zevallos. 2003). Processing makes improve shelf-life
and further more overcome seasonal gluts and perishability constraints. The major aims
of processing of fruits are to make the fruit microbiologically and chemically safe to
make convenient products with good flavor, color, texture and taste. There are many
ways to process and preserve the fruits (Holly Born and Janet Bachmann 2006). Food
processing increases the value of crops to farmers by providing higher returns, expand
marketing opportunities by creating alternative and additional means of marketing their
produce and increasing their income and reduce transport constraints and wastage
(Musyimi 2013).
2.3.3 Mango chemical properties
Usually, the ripe mango fruit consists of TSS 12.0-23.0 o Brix, 73.0-86.7% moisture
content, 0.12-0.38% acidity, 6.8-38.8% Ascorbic acid and 8.7-17.9% total sugar but
this amount may differs depends on the fruit cultivar (Jha S et al. 2010).Carbohydrates,
organic acid, protein, poly phenols, vitamins and minerals are the main chemical
constituent of mango fruit, ripe mangoes are sweet, rich in pro- vitamin A, moderate
vitamin C and aroma.
2.3.4 Nutritional properties and value of mango
Mango is an excellent source of bioactive compounds such as pro-vitamin A,
carotenoids, vitamin C and phenolic, as well as dietary fiber (Lemmens et al.
2013)essential to human nutrition and health. Moreover, mango is known to contain
other vitamins, carbohydrates and minerals such as calcium, iron and potassium, and to
be low in calories and fat (Table 1). Vitamin C is also reported to enhance iron
absorption and thus prevent anemia, improve collagen synthesis, immune system and
9
prevent cardiovascular diseases (Michael et al. 2009). The nutritional contents in mango
is affected by factors such as cultivar, growing conditions, stage of maturity and storage
(Lee, S. K. and Kader 2000; Mercadante, A. Z. and Rodriguez-Amaya 1998).
Processing of mango to products such as juices, purée, dried fruits and mango chutney
is important because of its seasonality, since it prolong its shelf life. However, the full
potential for processing has still not yet been explored, as a result, large amounts are
lost annually. The average nutritional composition of mango is described below in table
1 (USAD 2018).
Table 2 Average Nutritional content per 100g of raw mango pulp.
Component Amount
Water, g 83.5
Energy, Kcal 60
Protein, g 0.8
Total lipid(fat),g 0.4
Carbohydrate 15
Fiber(total dietary),g 1.6
Sugar(total),g 1.7
Calcium, mg 11
Phosphorous, mg 14
Iron, mg 0.16
Potassium mg 168
Vitamin C(total ascorbic acid), mg 36.4
Vitamin A, RAE, mg 54
Vitamin A, IU 108.2
Vitamin E (α-tocopherol), mg 0.9
Riboflavin, mg 0.04
Niacin, mg 0.67
Thiamin, mg 0.03
Vitamin B6, mg 0.12
Folate(DEF) 43
Source: Taken in part from USAD (2011), RAE retinol activity equivalent, IU:
international unity: DEF: dietary Folate equivalent
2.3.5 Processed Mango products
Processing of mango includes the transformation of mango fruits into different ready-
to-use products by adding value and it is a way of preventing food from spoiling. Mango
is a unique fruit in terms of the diverse products processed. In Ethiopia, mango
processing is not common considering the substantial amount of fruit that is
10
grown in the country. The major challenge for fruit processing sector in Ethiopia is due
to the presence of imported, extended shelf life mango products available throughout
the country so domestically produced products faced competitive entry barrier with
imported products. The other major problem is lack of technical knowledge in
processing, low level of technical support for maintenance, and low capital base
investments (Honja 2014; Ssemwanga, Rowlands, and Kamara 2008).
There are a number of mango products in the world, the most common processed mango
products are puree, nectar, juice, jams, jellies, canned slices, dehydrated pulp (mango
leather), and dried/dehydrated mangoes (Siddiq, Akhtar, and and Siddiq 2012). The
mango wastes like peel, seed are also contain many important nutrients and antioxidants
which can be used for different value added products in the pharmaceutical and
cosmetics industry (Larrauri et al. 1996). Some of processed mango products are
discussed below:
2.3.5.1 Mango pulp/puree
Mostly pulp and puree used interchangeable in naming, while the puree is more
“refined” since it has less fibrous content and smooth in consistency. These two
products acts as a base for a variety of processed mango products, like, nectar,
beverages, jam, jelly, and leather, before used to jam both pulp and puree are primarily
preserved by chemical preservatives, canning, or aseptic processing/packaging, and
occasionally by freezing (Kaushik, N., Nadella, T. and Rao 2015).
2.3.5.2 Mango Nectars
Mango nectar, a ready-to-drink beverage, is prepared by diluting single-strength mango
pulp with the addition of sugar, water, and preservatives to make a product with certain
percentage of mango pulp/puree. Mango nectar can be made either from mangoes
directly or from canned, aseptically packaged, or frozen puree. The use of honey as a
natural sweetener for mango nectar has also been reported to provide better value to the
product (Siddiq, Akhtar, and and Siddiq 2012).
11
2.3.5.3 Mango leather
In order to produce mango leather, mango pulp increased to 25°Brix and 0.5% acidity
by adding sugar and citric acid, respectively. This pulp, after mixing with 0.2% of
potassium metabisulphate it spread on stainless steel trays and dried at 55 – 60 °C to a
moisture level of 18-20 % in a cabinet drier. The dried material has a leathery
consistency is rolled and cut into pieces of convenient sizes. The pieces are then
wrapped in polyethylene sheet and packed in friction top tins (Anon. 2000).
2.3.5.4 Mango powder
Dried mango powder can be produced by drying mango puree to about 3% moisture
content. The mango powder can be stored up to six month in polyester or metalized
polyester pouches at 27–32 °C and easily reconstitute to the juice (Hymavathi, T.V. and
Khader 2005). There are different drying methods are reported like spray drying, freeze
drying, foam-mat drying, puff drying, vacuum drying and drum drying methods are
reported for the mango (Occena-Po 20066).
2.4 Jam production
Jams are thick; sweet spreads made by cooking and concentrating fruit pulp to a
moderately thick consistency along with addition of citric acid, pectin and sugar. Now
a day’s production of low calorie mango jam is started by substituting sucrose with
sorbitol (an artificial sugar) (Basu, S. and Shivhare 2013).
Productions of jam require knowing the right proportion of the ingredients to get the
desired results. In appropriate concentration of ingredients affects, their structure,
appearance, and mouth feel will since it is a result of a complex interaction between
pectin levels, pH, sugar content and setting temperature (Bhowmick, Devi, and Ghosh
2015).The quality criteria for jams and marmalades are decisively determined by the
flavor, color and consistency. These properties depend to a high degree on the quality
of raw materials used, with special importance given to the proper selection of suitable
fruits.
12
2.4.1 Ingredients for jam
The main ingredients require for jam production are fruit pulp, gelling agent,
sweetening agent, acidulant and coloring and flavoring agents.
2.4.1.1 Fruits
In manufacturing of jam different kinds of fruits can be used such as Fresh fruit,
frozen/chilled, or cold stored fruits (Nirmal et al. 2012). The main factor which
determines the quality of fruit for a certain process is its variety which affects the gelling
process. With the fruit increase ripeness the fruit is become favorable for jam
production since organic acid amount decreases and the sugar amount increases(Elias
abebe 2007).
The most important quality criteria for fruits used are: optimal state of ripeness, full
fruity flavor, variety-specific color, no blemishes (no spots, no bruises) and soluble
solids content in agreement with quality standards, perfect hygienic condition of raw
materials and packaging.
2.4.1.2 Gelling agent
Gels are intermediate forms between a solid and a liquid. They consist of polymeric
molecules cross-linked to form a tangled, interconnected molecular network immersed
in a liquid medium. The polymer network holds the water, preventing it from flowing
away. Pectin is a soluble gelatinous polysaccharide that occurs naturally in the cell walls
of higher fruits and is used as a hydrating agent and cementing material in jams
(Muralikrishna G 1994). Pectin concentration usually required for jam is around 1%,
however, it depends on the fruit type used in jam production. Pectin usually derived
from citrus (containing 25% pectin’s) and apple (containing 15-18% pectin) by-product
and added to jelly and jam formulations to achieve the desired gel strength.
Production of a satisfactory gel depends mainly on pH and correct concentration of
sugar and pectin. Many attempts have been made to explain the gelling mechanism in
sugar/ pectin/ acid systems. Originally, jam or jelly production relied on the role of
native pectin in fruit for gel formation (Nirmal et al. 2012). One theory relates
13
solubility of pectin to gel formation. Pectin is readily soluble in water at a low content
of soluble solids (below 25%). As the sugar content increases, pectin molecules will
precipitate due to the dehydrating effect of the sugar. The negatively charged pectin
molecules in solution repel each other. By lowering the pH (by adding hydrogen ions),
the negative charge is reduced and consequently facilitates hydrogen bonding of
adjacent pectin molecules. The precipitated pectin molecules form lattice trapping
water and solutes in the network (Featherstone 2016).
The rigidity or firmness of the structure depends on two conditions, partly the acid
expressed by pH and, sugar. Control of pH is critical to successful gel formation
conversely, less than pH 2.4, there will be no gel formation, similarly after pH 3.6,
(Baker et al. 2005). In the case of sugar concentration, where too-low content of sugar
(i.e., below 55%) will results in a too weak, or no gel formation, whereas, firmness of
jam will inverse with sugar content. However, too high a sugar content will cause
crystallization of the sugar.
2.4.1.3 Sweetening agent
Sweeteners are one of the main constituents of jams, jellies and marmalades and used
in fruit processing for many functional reasons. They add flavor and control viscosity
of the product. Although it contributes to texture and preventing spoilage by bind
moisture in fruits. For jam production refined/granular/white sugar should be used and
the final concentration has to be high enough (>68%) to prevent fermentation by molds
or yeasts, but low enough (<72%) to prevent crystallization. If the TSS has not reached
to the desire oBrix jam failure can occur (Nirmal et al. 2012).
2.4.1.4 Acidulant
The most common acid used in jam manufacturing is citric acid. Acid in fruit processing
have many function as acidifier, pH regulator, preservative, flavoring agent and
gelling/coagulating agent etc. Fruits which are naturally low in acid are less suited to
jam preparation. Mainly, organic acids are using in jam preparation in order to reduce
the pH to the value recommended gel formation. In addition, it is also enhances the
flavor, taste and also possesses preservative effect. The fruit must have optimum level
of acidity (pH 3.0-3.3) to enable the pectin to form a gel. If the pH
14
value is less than 3, this may lead to jam bleeding .When exceeding a certain pH limit,
gelatin is no longer possible (Nirmal et al. 2012).
2.4.1.5 Coloring and Flavoring Agents
A good jam should appeal to the eye as well as to the palate. For jams produced from
fresh fruit there is no need of using additional colorant and flavor. However, the natural
color and flavor of the fruit always affected by heating, so artificial additives are added
but using it is become less acceptable by consumers. In order to restore the original
natural appearance only permitted edible food colors and flavor components are
important. Natural food flavor can be extracted from citrus oil and fruit volatile
compounds to improve product aroma and added near completion of boiling (Nirmal et
al. 2012).
2.4.2 Method of manufacturing jam
The basic steps for the manufacture of jam includes the preparation of fruit, boiling,
filling, packaging and its detail is discussed below:
2.4.2.1 Fruit preparation
Fruits for jam making should be optimal state of ripeness, possess a rich fruity flavor,
attractive pulp color, sufficient consistency and soluble solids content. Fruits usually
washed thoroughly with water to remove any adhering dirt.
2.4.2.2 Juice extraction
Juice from fresh fruits is extracted by crushing and pressing them. During extraction,
the juice should not be unduly exposed to air, as oxygen in the air will adversely affect
the color, taste, and aroma and also reduce the vitamin content of the juice (Bhowmick,
Devi, and Ghosh 2015).
2.4.2.3 Boiling
Boiling is one of the most important steps in the gel making process, as it dissolves the
sugar and causes union of the sugar, acid and pectin to form a gel. The behavior of the
fruit when cooked in sugar syrup varies with the variety. The main purpose of the
15
heating is to increase the concentration of the sugar until soluble solids material reached
57.0-68.0º Brix by evaporating the excess amount of the water (Salih 2008).
Concentration of jam also required to create finished product with long shelf life.
Boiling in commercial practice is usually conducted in open steam jacketed stainless
steel kettles in this method the boiling time should be short to reduce loss of flavor,
change of color and hydrolysis of pectin. The other boiling method is using of vacuum
pan to minimize the undesirable changes and loss of vitamin C but boiling can be carried
out for long time in lower temperature (65–760C ) to soften the fruit pieces, resulting in
some loss of flavor, which can, however, be restored by recovering the volatile esters
and putting them back in to the jam (Nirmal et al. 2012)
There are three methods to determine the end point of jam; the first method by placing
some of the jam in a cup filled with water, if the color of the water did not changed and
the drop settled as solid matters at bottoms of the cup that means the end point has been
reached. The second is using refractometer, it is a digital method which measuring the
total soluble solid content of the product, when it reaches 60-68ºBrix the jam is ready.
The third method is using thermometer when the temperature of the mixture reaches to
103 – 105ºC, this means the jam is ready (Ahmed 2007).
2.4.2.4 Filling and Packaging
The packaging material used for jam should be hermetically sealed container to prevent
against gas vapor, microorganisms and dirt entry (Degafe.T 2013). Glass is the usual
material, although enamel-lined tin cans and special containers are also used. Glass is
a popular packaging option for jams and jellies, as it displays the product well, as well
as having a good shelf life once opened.
The glass containers should be cleaned using an inverting type air cleaner or water prior
to filling. The container preheated to prevent the cracking of the glass by entry of the
hot product. It also reduce the possibility of spoilage so, the containers must preheated
prior to filling. The filling of jams comprises three main steps:
(1) Pre-cooling prior to filling: Normally, the jam is cooled down to around 71
°C and sometimes to as low as 60 °C prior to filling.
16
(2) Filling: The filling and capping operations for jams and jellies are so closely
related, they will be treated as one subject. Filling requires the proper weight of
finished product be placed in the container and that the material so placed in the
container be truly representative of the batch. Piston fillers are generally used
for both jellies and jams; the filling temperature may vary with the type of
product being filled. Jam products filled at a temperature below 85°C should be
pasteurized after hermetic sealing.
(3) Sealing: Immediately after filling, the containers should be sealed with a
positive hermetic seal, which can be a top-side seal. Efficient cooling system is
necessary to manage this process. These jams should be cooled until they are
near setting point, but great care must be taken not to exceed the limit, otherwise
the set will break and the jam curdles, more so in the case of jellies (Nirmal et
al. 2012).
2.4.3 Quality standards for jam
Jams and jellies are widely used in nearly every part of the world. Large numbers of
units are manufacturing jams and jellies to cater the demand of domestic and export
market. Each year many new types of jams and jellies appear on retail shelves and
represent competition for the traditional ones. Improvements in processing techniques,
more basic knowledge about fruit characteristics, and competitive situations have
resulted in a great increase in the overall quality of the products. There are different
reasons which cause jam failure. The first quality parameter in production of jam is
total soluble solid content which should be in the range of 57 – 68ºBrix (Malcolum
2005).
In the production of mixed jam the first named fruit should contain amount to not less
than 50% and not more than 75% of the fruit content (Kordylas 1990). The second
named fruit required to be present in 25% of the fruit content or less if more than two
fruits mixed (Pearson 1976). The content of toxic contaminants, Arsenic (1.1 ppm),
Lead (2.5 ppm), Copper (3.0 ppm) and Zinc (50 ppm) in jam must be less than standers
amounts (Ameliaa Jeanroya and karen Ward 2000). The FPO specification for jams and
jellies recommended standards of FAO/WHO Codex Alimentarius Commission are
quoted under jams (fruit preserves) and jellies CAC/RS 79/80-1976
17
regarding their composition, formation, soluble solids of the finished products, and
quality criteria as stated in the table 3 (Ranganna 1986). The final product should
contain 30–50 % invert sugar of the total sugar in the jam. If the percentage is less than
30%, sugar may crystallize out on storage, and if it is more than 50% the jam will
become a honey-like mass because of the formation of small crystals of glucose and
TSS value will not report not more than 68%. The finished product should contain at
least 0.5 %, but not more than 1.0 % total acids because of larger quantity of acid may
cause syneresis. Gel strength increases with the increase in pH until an optimum is
reached. In general, the optimal pH value for gel is 3.2 (Bhowmick, Devi, and Ghosh
2015).
2.4.3.1 Jam failure
The main reason which can cause jam failure is:
• The imbalance between the concentrations among sugar, pectin, acid and raw
material.
• The quantity and mixing time of pectin
• When the total soluble solids have not being reached the final desired Brix
degree as it is discussed in the table 3 below.
• When pH value above or below 3, when the pH –value is less than 3 may
lead to jam bleeding (Salih 2008)
Table 3. FPO Specifications of Jams and Jellies
Determination Specification
Fruit content TSS Not less than 45% exception: raspberry and
strawberry
Jams- not less than 68% w/w
Jelly –not less than 65%w/w
Preservatives(Sulfur dioxide)
Benzoic acid
Not more than 40ppm
Not more than 200ppm
Synthetic (Sweetening agent) Not permitted
Added color Permitted color
18
Mold growth Absent
Fermented test Negative pressure at sea level retain flavor of
original fruit free from burnt or other objectionable
flavor
Crystallization Absent
Source: Ranganna 1986, (Nirmal et al. 2012)
19
3 MATERIALS AND METHODS
3.1 Experimental Material
The sample of mangoes used in this study was harvested from April to June, 2018. The
minimum and maximum temperatures were 17.78oC and 28.89oC, respectively.
Mangoes were harvested at an altitude of 1,820 meters (5,970 ft) above sea level. Six
popular cultivar as shown below in figure 1 namely Tommy Atkins, Keitt, Kent, Dodo,
Local and Apple used in this study were collected from Adet Agricultural Research
Institute Weramit fruit and vegetable center, Bahir Dar, Ethiopia. Additional
ingredients like sugar, pectin (Purix powdered pectin) and citric acid were purchased
from laboratory equipment and chemical suppliers in Addis Ababa. The laboratory-
based experimental was conducted at Bahir Dar Institute of Technology in Food
processing laboratories.
(A) (B) (C)
(D) (E) (F)
Figure 1. The mango cultivar used in this study
(A) Local mango (B) Keitt mango (C ) Dodo mango (D) Kent mango (E) Apple mango (F)
Tommy mango
20
3.2 Experimental description
3.2.1 Study 1: Characterization of mango for jam suitability
Six mango cultivar (Tommy Atkins, Keitt, Kent, Dodo, Local and Apple) subjected to
this study were sorted based on uniformity in shape, size, color, ripeness, free from
damage (bruises). Selected mango fruits were cleaned to remove dust from the surface,
washed and peeled manually using knife. The flesh was cut away from the seed using
a knife and then homogenized using electrical juicer. Juice obtained was passed through
a muslin cloth and subjected to physico-chemical analysis according to the methods
specified in section 3.3.
3.2.2 Study 2: Jam formulation and physico-chemical analysis
Based on the results obtained from the characterization, one mango variety was selected
depending on the most important characteristics which are needed for jam making and
mango jam was prepared as shown in Figure 2.
3.2.3 Methods of jam making
First 20 kg of Apple mango was taken from Adet Agricultural Research Center and
brought to BIT, food process laboratory. The fruits were washed, peeled, sliced and
pulped using electric blender. After the mango was pureed mango jam was prepared by
taking pectin, sugar and pH concentrations according to the specified design (Table 4).
250 ml of prepared puree was taken to prepare each sample of mango jam in to cooking
kettle. The addition of ingredients during cooking process is divided into two steps.
First, half amount of the sugar (250g for 50% and 300g for 60%) and, then citric acid
was added to the pulp in cooking kettle. The amount of citric acid was calculated by
preliminary trials (to adjust the pH).Boiling process was continued and then stirred well
until 50 ºBrix of solids was reached. The remaining quantity of sugar was added, stirred
well until 64ºBrix of solids reached then pectin (50g for 1% and 70g for 1.5 %)was
added and stirred well until the solids reached 67-68ºBrix, then previously sterilized
jars were filled while the mixture was hot and then quickly
21
sealed hermetically and cooled (Baker et al. 2005). The prepared mango jam was
subjected to physico-chemical and sensory analysis.
Figure 2. Flow diagram for mango jams production
3.3 Experimental design
For the evaluation of the six varieties for their potential for jam making the
experimental design was conducted on CRD design
• Factor – varieties
• Level – 6
By comparing the physic-chemical properties of six varieties, one best variety which is
suitable for jam making was selected. During jam preparation experiment full factorial
experimental design was used as shown in table 4. This factor was selected since the
property of the jam depends on sugar, pectin and acid ratio and based on the previous
study conducted by (Afoakwa.E, Nartey.E, and Annor.G 2006) Statistical data analyses
will be carried out by SAS for the fruit where as Minitab was used for the jam.
Fresh mango Sorting Washing and
peeling Cutting and
crushing
Add the remaining
sugar
boiling untill 50 ºBrix
Weighing and mix with
1/2sugar and citric acid ,
Mango puree
Boil untill 64ºBrix
Add pectin
Jam gela tion tiniza
( - until 68 70obrix)
Filling in sterilized
bottle
Storage Setting of jam Cooling
22
(%) =
– 100
• Factor – 3( pectin, sugar and pH)
• Level – 2*3*2 respectively
Table 4. Full factorial design table with different factors and levels for jam preparation
Sugar Pectin 1 Pectin 2 Pectin 3
pH 1 pH2 pH1 pH2 pH1 pH2
S1 S1P1pH1 S1P1pH2 S1P2pH1 S1P2pH2 S1P3pH1 S1P3pH2
S02 S2P1pH1 S2P1pH2 S2P2pH1 S2P2pH2 S2P3pH1 S2P3pH2
Whereas S is Sugar (S1:50%, S2:60%), P is Pectin (P1:1%, P2:1.5%, P: 0%) and pH
(pH1:3, pH 2:3.3)
3.4 Physico-Chemical characterization of mango variety
3.4.1 Determination of pulp percentage
The pulp percentage was determined according to the method of (Vibhakar et al. 1972).
Mango fruit samples from each variety were weighed ,peeled and all the edible pulp
was extracted with an extractor. The extracted pulp was then filtered through muslin
cloth and quantity was measured. The percentage pulp recovery was calculated as the
following equation 1:
..................................... Equation 1
3.4.2 Determination of Total Soluble Solids (TSS)
The TSS was determined according to AOAC method 932.12 (AOAC. 1999) using an
hand refractometer (RX 5000, Atago, Tokyo, Japan). One ml of a well homogenized
mango juice was placed on prism of calibrated hand refractometer. The readings were
taken and results were expressed in ºBrix at 200 C.
3.4.3 Determination of moisture content
Moisture content of the samples were determined according to AOAC method 934.06
(AOA.C 2008) by using hot air oven. An empty dish was dried in air oven at 105° C
for 3 hrs and transferred to desiccators to cool. Then 3g of mango pulp samples
accurately weighed (PW-184Adam Analytical Balance) and dried in a hot air oven (DH
-9140) at 105° C for 3 hrs. The dried dishes are transferred to desiccators to cool
23
(%) = ∗ 100...
ℎ(%)
= .....
and reweighed, until sample reached to constant weight. The percent moisture content
was calculated as percent loss in weight using the Equation 2,
.......................................................................................................Equation 2
Where,
W1 = Weight (g) of sample before drying
W2 = Weight (g) of sample after drying
3.4.4 Determination of ash content
The ash content of the samples was determined by the method described by AOAC
method 942.05 (AOAC.. 2000). The empty crucible along with lid was placed in the
furnace (Nabertherm GMBH) at 550oC then cooled in desiccators for 30 min and
weighed (W1). The sample (5 g) was weighed (W2) in to the crucible and heated over
low Bunsen flame with lid half covered until combustion of the sample was done, than
crucible was closed with lid and placed in furnace at a temperature of 500-550° C for
8hr. Then, the crucible was cooled desiccators. The ash with crucible and lid were
weighted when the sample turned gray (W3). The percent ash content was calculated
using Equation 3:
......................................................................................................... Equation 3
W1=Mass of crucible and lid
W2=Mass of fresh sample and crucible and lid
W3=Mass of crucible and ash
3.4.5 Determination of pH
The pH value of each sample was determined by using digital pH meter (PH,815) by
AOAC official method 981.12(AOAC... 2000). The pH 4.0 and 7.0 buffer solution was
used to calibrate the pH meter (Ranganna 1986). The electrode assembled to the pH
meter was dipped into the 50ml of fruit juice samples; reading was recorded and washed
twice with distilled water before moving to the next sample.
24
( /100
) =
∗ ∗ . ........ .....
3.4.6 Determination of Total Titratable Acidity (TTA)
TTA was analyzed by the AOAC method 942.15 (AOAC 2000). Ten ml of fruit juice
was diluted to 250 ml using distilled water. An aliquot (50 ml) was mixed with 0.2ml
phenolphthalein indicator and was titrated it with 0.1 N NaOH to the first appearance
of pink endpoint. TTA expressed as mg of citric acid per 100 g fruit using the Equation
4:
............................................................................... Equation 4
Where
TTA= Total titratable acidity
N = Normality of NaOH
V1 = Volume of NaOH used (ml)
Eq.Wt. = Equivalent weight of citric acid (g)
V2 = Volume the sample (ml)
3.4.7 Determination of Total sugar
Total sugars were assessed according to Lane and Eynon titrometric method (AOAC.
1999). Twenty-five grams of the mango pulp (3g of mango jam) was filtered through
Whatman filter paper (No. 4) and then transferred to a 250ml volumetric flask. A 100ml
of distilled water was carefully added and then neutralized with (1.0N) NaoH to a pH
of 7.5-8.0. About 2ml of lead acetate solution was added and the flask was then shook,
and left to stand for 10minutes, then 2g of sodium oxalate was added to remove the
excess amount of lead. Distilled water was again added to make up the volume to the
(250ml), and the solution was filtered. A 50ml of the filtrate were pipette into 250ml
volumetric flask. To the new mixture 50g of citric acid and 50ml distilled water were
slowly added. The content of the flask was boiled gently for 10minutes to invert the
sucrose, and then cooled; few drops of phenolphthalein indicator were added. In order
to neutralize the mixture, a 20% NaoH solution was continuously added till the color
is turned pink. Immediately, (1.0N) HCl was added
25
he perc entage of tota
100
l su
=
g ar
∗..............
= ∗
∗ ∗
∗ ..............
100 = ∗ ...............
= ∗
∗ ∗
∗ ..............
till the color of the solution disappeared, and the volume was made to mark before
titration.
Standard method for titration
Ten ml of a mixed solution of Fehling (A) and (B) were pipette into a conical flask. A
burette was filled with the clarified sugar solution and running the whole volume
required to reduce the Fehling’s solutions so that, 0.5-1.0ml was still required to
complete the titration. The content of the flask was mixed and then heated to boiling
for 2minutes. Three drops of methylene blue indicator were added. Then the titration
was continued till color completely disappeared.
Calculation:
T was calculated by Equation 5 and 6
............................................................ Equation 5
% ........................................... Equation 6
The factor was obtained from glucose table (Pearson 1976)
3.4.8 Reducing sugars:
For most fruits, the reducing sugars were very low, so that filtrate can be used directly
for titration according to number 925.35 using Equation 7 and 8:
.................................................... .Equation 7
% ..................................... Equation 8
The factor is obtained from glucose table (Pearson 1976).
3.4.9 Determination of Vitamin C content
Vitamin C determination was carried out by titration method (Robert.G and Steel.D
1980). Thirty grams of fruit flesh was weighed and blended with equal weight of 6%
meta-phosphoric acid for 3 to 4 minutes. Fifteen grams of this slurry was taken in
26
= ∗ ∗ 100
a100 ml volumetric flask and it was made up to volume by adding 3% meta- phosphoric
acid. This juice was filtrated through a fast filter paper.
Titration: The burette was filled with standardized 2, 6-dichlorophenol indophenols
dye reagent. Ten ml of filtered solution was taken in a conical flask and titrated
immediately against standard dye solution, till faint pink color was observed which
persisted for not less than 15 seconds. The ascorbic acid content calculated using the
following Equation 9.
....................................................................... Equation 9
Where, v = volume of dye used in titration against an aliquant diluted sample,
t = value of standardized dye used to titrate the standard,
w = weight of pulp.
3.5 Sensory analysis of the final jam
A panel of 12 untrained panelists was selected randomly. Sensory evaluation was done
using a five point hedonic scale to collect acceptance of the product in different aspects
(Larmond.E 1977). Sensory analysis was carried out in the Food process laboratory,
Department of Food Engineering, Bahir Dar, Ethiopia. The panelists were selected
solely on the basis of interest, time available and lack of allergies to food ingredients
used in the study. On every occasion, the panelists were provided the randomly coded
disposable paper plates containing different samples. The samples were tested for
different parameters like Appearance, color, flavor, consistency and overall
acceptability. The hedonic scale was used as 5 (like extremely), 4 (like slightly), 3
(neither like nor dislike), 2 (dislike slightly), 1(dislike extremely). The panelists were
briefed how to use sensory evaluation forms and terminologies of sensory attributes.
27
3.6 Statistical analysis
For study 1: Characterization of mango for jam suitability
The data obtained from mango cultivar was subjected to statistical analysis using SAS
9.1 software. The analysis of variance (ANOVA) was performed to examine the level
of significance effect in all parameter, Duncan multiple range test was used to compare
the significance difference among means at p<0.05.
For study 2: Jam formulation and physico-chemical analysis
For the data obtained from characterization of jam, Analysis of variance (ANOVA) was
applied. The data was analyzed using Minitab statistical software version 16.0. For
Sensory analysis of jam data was analyzed by using SAS 9.1 software Significance was
accepted at P< 0.05 using Minitab Statistical Software (Version 16.0, 2008)
28
4 RESULTS AND DISCUSSION
4.1 Physico-chemical properties of the mango cultivars
The physico-chemical properties of the six mango cultivar (Keitt, Kent, Dodo, local,
Tommy, Apple) were studied and the results were presented in table 5. The results
obtained from the fresh mango were compared to show the varietal differences among
the six cultivar.
Table 5.The physico-chemical properties of mango cultivars
Variety Juice (%) TSS pH Acidity Ash Moisture Reducing sugar Total
(oBrix) (mg/100g ) (%) (%) (%) Sugar (%)
Tommy 74.30±0.29c 15.34±0.02b 3.54±0.02e 0.47± 0.01c 0.24±0.10d 77.65±0.48a 2.00±0.00d 13.88±0.02b
Keitt 70.41±0.62e 12.04±0.01e 4.33±0.05c 0.35±0.01d 0.45±0.06cb 75.65± 0.37c 2.31±0.02c 12.14±0.77c
Kent 75.29±0.31b 13.02±0.02d 4.17±0.02d 0.23±0.01f 0.65±0.02a 76.56±0.29b 2.33±0.06c 11.46±0.49dc
Dodo 72.70±0.10d 11.90±0.02f 4.75±0.03a 0.83±0.01a 0.49±0.01b 77.45±0.22a 2.28±0.03c 9.37±0.30e
Local 65.45±0.30f 13.38±0.03c 4.47±0.01b 0.61±0.02b 0.47±0.03b 77.78± 0.27a 2.86±0.06a 10.83±0.40d
Apple 78.14±0.64a 17.06±0.01a 3.33±0.03f 0.27±0.01e 0.36±0.05c 71.30±0.24d 2.63±0.03b 15.57±0.11a
All Values expressed with similar subscripts are not significantly different All values were means of three replications
29
30
4.1.1 Juice percentage
The cultivar of the fruits showed significant (p<0.05) difference among the pulp
percentage. Analysis of the fresh mangoes revealed that maximum pulp percentage
(78.14%) was found in Apple mango variety and the minimum was observed in Local
(65.44%) cultivar.. The local mango variety possesses a big seed and small quantity of
flesh in contrast to Apple mango. The percent of pulp for some Sudanese mango
cultivar GulbAltour, Magloba and Abusamaka were reported in the range of 72.4-
75.48 % (Nour 2011). Another study reported the pulp percentage of six mango cultivar
from Pakistan Chaunsa, Dusehri, Langra, Malda, Anwar Ratol and Fajri were in the
range of 67.93-77.62% (Muhammad et al. 2012). The variation in pulp amount is
attributed to the varietal difference and growing conditions. The ideal mango fruit for
the jam preparation, is benefit from good firmness, appropriate consistency, fiber
absence, and an adequate sugar and acid content (Pleguezuelo et al. 2012). In this sense,
the highest pulp percentage was found for Apple mango fruit which makes it most
valuable fruit for jam preparation than others.
4.1.2 Moisture content
The moisture content of the pulp was found to be in the range of 77.65% - 71.30%.
There is a significant (p < 0.05) difference between the six mango cultivars in terms of
moisture content. Previous reports showed the moisture content in the range of 72.04-
79.76 % (Mohammed 2013). The moisture content values of 56.6% - 86.1% were also
reported for different mango cultivar (Othman, OC and Mbogo 2009). The moisture
content obtained in this study was within the reported ranges. Moisture content decides
the shelf life of the fruit and high moisture content of fruit is not desirable for jam
production(Fellows 2009). A fruit with high moisture content require high temperature
and long time to concentrate the jam to the required o brix and high temperatures during
preparation or subsequent storage reduced quality and requires high processing time
and energy at the industrial level. Ultimately, Millard darkening and off-flavor
development occurs in this high temperature process (Bates, Morris, and Crandall
2001). This makes Apple mango more suitable for jam preparation.
31
4.1.3 Ash content
The ash content was found in the range of 0.243- 0.65%, showing significant difference
(p<0.05) among the mango cultivar. Ash content represents inorganic matter (minerals
like calcium, potassium and iron) in a given sample. The ash content of four mango
cultivar local, Palmer, Keitt and Améliorée reported between 0.32-0.49
% (Mbome 2008) and past study reported the ash content of three mango cultivar (
Abusamaka, GalbAltour and Magloba) as 0.67%-1.10 % (Nour 2011). The ash content
in this study is within the range of the two results. High ash content(Calcium) is
desirable for jam processing since high ash content indicate mineral content in the fruit
(Ashaye, OA., Taiwo OO 2006).
4.1.4 pH
pH is the measurement of the acidity or alkalinity of a fruit. In this study the pH value
of the pulp of the six mango cultivar found in the range of 3.33- 4.75 and showing
significant (p< 0.05) differences among the mango cultivar. The maximum pH value
was recorded in Dodo mango variety and the minimum value was in Apple mango
among the all. The pH value of mango was reported in past studies as 3.8-4.5 (Musyimi
2013). The pH content of Kent, Dodo and local cultivar were within the range and the
other three are below in the reported range. These variations may be attributed to the
variety differences. The pH value of the fruit is an important factor in jam processing
since it is related with gel formation. The pH value recommended for jam production
is between 3 and 3.5 (FAO. 2009). The optimal pH for pectin gelatin is between pH 2.8
and 3.5 in which Apple mango variety fits this range There are a few other factors
involved in achieving the perfect set and getting pectin to gel properly, but pH is
definitely key factor (Janice Lawandi 2015).
4.1.5 Titratable Acidity
Titratable acidity is a measure of the buffering capacity of fruit and is generally
expressed as citric acid. The main organic acids in mature mango fruits are citric, malic,
succinic and tartaric acids (Medlicott AP 1985). Titratable acidity (TA) decreases with
fruit maturity and aromatic volatiles are produced at advanced stages of fruit maturity
in most fruits (Tharanathan, Yashoda, and Prabha 2006; Yahia.E.M.
32
1994). The TA found in this study is in the range of 0.23-0.83 mg/100g showing
significant (p<0.05) differences among the acidity of six mango cultivar. In this study,
Dodo had the highest (0.83) and Kent mango variety (0.23) had the lowest value for
TA.
As (Musyimi (2013)reported TA of six mango varieties (Apple, Ngowe, Tommy
Atkins, Kent, Vandyke and Sabine) ranged between 0.31-0.471mg/100g.The results
obtained in the present study has little deviation. This variation might be due to
difference in some of the variety. The right amount of acid is critical to gel formation,
with too little acid the gel will never set and too much acid will cause the gel to lose
liquid (Nirmal et al. 2012). Fruits with low organic acid concentrations require the
addition of lemon juice or other acid ingredients to ensure gelling in jam preparation.
Acid facilitates the release of trapped pectin inside the fruit cells during heating of fruit
with sugar. Then the pectin is dissolved and free, the strands of pectin repel each other
because they carry an electric charge (negative).Without the help of lemon juice the
pectin strands can’t come together to form a network that will set your batch of jam.
The lemon juice lowers the pH of the jam mixture, which also neutralizes those negative
charges on the strands of pectin, so they can now assemble into a network that will “set”
jam(Janice Lawandi 2015).
4.1.6 Total soluble solids
The main chemical parameters of fruit quality are their total soluble solids content and
titratable acidity (David H. Byrne; 2012). As reported that the TSS and Titratable
acidity of mango fruits are usually associated with metabolism (Sabato, S. F, Da Silva,
J. M. and da Cruze 2009). Therefore, TSS of the fruit varies from variety to variety as
well as growing condition, as the fruit matures the TSS content will increase. In this
study, the TSS content of the six mango cultivar was found to be in the range of 11.90-
17.06 ºBrix and showing significant (p<0.05) difference among the TSS of these mango
cultivar. Researchers reported TSS in the range of 7-20 oBrix (Kumar 2008). Another
study found that average range of TSS from11.35-28.96 oBrix in 11 mango cultivar
(Kaur et al. 2014).
33
4.1.7 Total sugar
Sweetness is the most important compositional parameter related to mango flavor. As
mango fruit ripens, soluble sugars increases as starch content is hydrolyzed to simple
sugars (Ito, T., Sasaki, K. and Yoshida 1997). The total sugar content of mango fruit
varies with variety. The total sugars content of the six mango cultivar in this study was
found in the range of 9-15.57%, showing significant (p<0.05) difference among the six
mango cultivar. Apple mango had the highest total sugar and Dodo variety has the
lowest. (Jilani et al. 2010) reported total sugar from 15 to 20%, in different cultivars
(Alphanso, Anwar Retual, Dusehri, Fajri, Gulab-e-Khas, Langra, Malda, Sanglakhi,
Sindhri, and Suwarnareeka). These variations in sugar content may be due to the
cultivar difference and climate conditions.
The variation in sugar contents between different mango cultivar may be attributed to
physiological changes and polysaccharides metabolism during ripening process that
contribute to accumulation of simple sugars (Sabato, S. F, Da Silva, J. M. and da Cruze
2009). As the total sugar value is lower the amount of additional sugar in jam processing
will be high which is not desirable for cost as well as consumer health perspective. High
total sugar value in mango variety is therefore preferable for the production of jam.
4.1.8 Reducing sugars
The values of reducing sugars in this study were found in 2-2.87% showing significant
(p<0.05) differences among mango cultivar. From the six mango cultivar) Dodo, Keitt
and Kent have statistically similar reducing content. (Kaur et al. 2014) reported higher
averages of reducing sugars from 3.40 -19.27%. Whereas, (Nour 2011) reported
reducing sugar value in range of 2.96-3.45 % from three mango cultivar and the results
obtained in this study is lower than the reported range. This may be attributed to the
difference in production area and variety.
34
Selected mango variety
Desirable attribute for Jam production had been obtained from Apple mango this
makes it more suitable for preparation of jam.
Table 6: Apple mango chemical composition
Cultivar TSS TA TS Juice %
Apple 17.06 0.27 17.06 78.14
4.2 Physico-chemical properties of mango jam
The physico-chemical properties of foods ultimately determine their perceived quality,
sensory attributes and behavior during production, storage and consumption. The jam
samples were studied for Physio-chemical properties like pH, moisture, ash, total
acidity, soluble solids, protein and Vitamin C. Mango jam was prepared by using Apple
mango cultivar and the Physiochemical attributes of different formulations of jam are
presented in the following tables 7.
Table 7. The physicochemical properties of mango jam
pH Pectin Sugar MC (%) AC (%) TA c TS (%) RS (%) Vitamin C(mg/100g )
3
1%
50% 26.31±1.06b 0.38±0.01d 0.52±0.04cd 57.45±0.40cd 34.66±0.19b 21.23±0.31cd
60% 25.82±0.59c 0.47±0.01bc 0.41±0.01fg 59.73±0.90bc 33.58±0.01c 20.57±0.21d
1.5%
50% 24.613±0.55bc 0.49±0.02b 0.52±0.00cd 60.66±0.99abc 31.13±0.058e 20.5±0.1d
60% 23.84±0.50cd 0.45±0.01c 0.44±0.01ef 63.72±0.55a 33.04±0.04d 21.57±0.26bc
0%
50% 29.87±0.92a 0.32±0.01ef 0.71±0.02a 47.52±0.72efg 28.13±0.15g 17.23±0.31g
60% 29.11±0.43a 0.33±0.01e 0.45±0.02ef 48.22±1.33ef 26.13±0.06i 18.57±0.15e
3.3
1%
50% 26.56±0.47b 0.29±0.02f 0.62±0.01b 55.27±0.63d 34.26±0.38b 22.24±0.46b
60% 25.23±0.92bc 0.39±0.01d 0.56±0.021c 62.44±1.07ab 35.70±0.02a 18.63±0.25e
1.5%
50% 23.73±0.80cd 0.34±0.01e 0.63±0.01b 50.31±2.36e 32.74±0.07d 23.99±0.072a
60% 22.02±1d 0.55±0.011a 0.36±0.01g 63.42±1.18a 31.55±0.15e 20.77±0.36cd
0% 50% 29.13±1.05a 0.46±0.01bc 0.56±0.02c 44.45±1.10g 27.1±0.1h 18.1±0.46ef
60% 29.71±0.95a 0.44±0.02c 0.49±0.01de 46.41±1.36fg 29.766±0.06f 17.7±0.1fg
• All Values expressed with similar subscripts are not significantly different by Duncan multiple range Test across the columns (p ≤ 0.05).
• All values were means of triplicate determination ± SD
• Whereas MC: moisture content, AC: Ash content, TA: Titratable Acidity, TS: Total Sugar, RS: Reducing Sugar
35
36
4.2.1 Moisture content
Moisture content in any food commodity plays a key role in deciding its shelf life
(Fellows, P. and Quaouich 2004). The interaction effect of pH, pectin and sugar
significantly (p<0.05) affect moisture content of the mango jam as shown in Appendix
B. The moisture content in the present study is found in range of 22.01 to 29.87%.
Sample 5 (pH 3, pectin 0% and sugar 50%) presents the highest moisture whereas
sample 10 (pH 3.3, pectin 1.5% and sugar 60%) had the lowest moisture content.
Previous study has found MC of 45.6-46 % in 3 different mango fruit jams (Mohammed
A.Y. Abdualrahman 2013) which is
The moisture content in each jam sample has significant difference from that of the
fresh mango fruit due to heat treatments in the preparation of jam. Most of the time high
sugar content makes the moisture not available as free water. This bound water may not
be readily available for microbial growth and prolong the shelf life of the jam hence;
low moisture content is preferred for stable storage of jam. Finally, for low making low
moisture content jam 3.3 pH, 1.5% pectin and 60% sugar can be used.
4.2.2 Ash content
Ash content represent the total inorganic matter in a sample, high ash content indicates
the jam is rich source of minerals. Ash content of apple mango jam was in range of 0.29
to 0.55%. The interaction effect of pH, pectin and sugar significantly (p<0.05) affect
ash content of the mango jam aas shown in Appendix B Table 6 shows that as the sugar
and pectin concentration increase the amount of ash also slightly increase in some
treatments.
The ash content of 0.32%-0.34% was reported in previous study (Abdualrahman 2013),
the variation in ash content is due to variation in inorganic compounds especially
calcium ion present in pectin as well as in the added sugars.
4.2.3 Titratable acidity
The titratable acidity is one of the important physic-chemical parameters which affect
product quality and sensory acceptability to a large extent. Titratable acidity value of
37
jam is the result of organic acids present naturally in fruits and those added while
preparation of jam. The titratable acidity of apple mango jam reported in this study is
range from 0.36-0.71 mg/100g. The interaction effect of pH, pectin and sugar
significantly (p<0.05) affect titratable acidity of the mango jam. As the concentration
of sugar increase from 50-60% the titratable acidity value has slightly decreased.
Whereas, the pH value increases from 3-3.3 the titratable acidity also increase. The
acidity in jams was reported in the range of 0.6-0.8mg/100g by previous study (Anon
1990). The minor variation of titratable acidity value may be due to the level of pectin,
sugar and acid used in this study. Since acid facilitates the release of trapped pectin
inside the fruit cells during heating of fruit with sugar, low titratable acidity is important
in facilitating conversion of added sucrose during cooking and prevents crystallization
and also gives imperative effect on the gelatinization property of pectin.
4.2.4 Total sugar
The sugars present in jam comprise natural and added sugar and it is an important
preservative. Total sugar content of apple mango jam prepared in the study was in the
range of 48.22-63.41%. The result of total sugar indicates significant (p<0.05)
difference among the different combinations of pH, pectin and sugar as well as their
interaction effect. The above result showed that as the amount of added sugar is
increased in the formulation of jam the total sugar also increase. Similarly, as the pectin
concentration increase from 0-1.5% the TS value also increased. Total sugar content
was found in a range of 38.86% to 62.53% by previous reports (Ahmmed, Nazrul Islam,
and Saidul Islam 2015). The values of total sugar in all jam samples were higher than
in fresh fruits, mainly due to addition of sugar as well as thermal processing. Generally,
high total sugar content was observed in the jam formulated from pH 3.3, 1.5% Pectin
and 60%Sugar.
4.2.5 Reducing sugar
Reducing sugar of the jam was significantly (p<0.05) affected by all the major effects
and interaction effect of pH, sugar, pectin levels where as (p>0.05) with pectin and
sugar interaction. The reducing sugar content of the jam ranged from 26.13-35.70%.
38
The highest reducing sugar is reported by sample 8(pH 3.3, pectin 1% and sugar 60%)
whereas, the lowest reducing was at sample 5 (0pH 3, pectin 0 % and sugar 50%). This
result is in agreement with previous study by (Nour 2011), who reported reducing
sugars of three mango cultivar GulbAltour, Magloba, Abusamaka ranged between
26.13-35.70%.In another study (Khalid (2009) found out that reducing sugar of mango
Jams ranged from 33.63-21.94%. The range of reducing sugars is close to the present
investigation. The reducing sugar content require for jam is high because of sugars are
essential in order to preserve the jam satisfactorily and also for the sweet taste. In
addition to that, sugar can increase gel strength and reduce syneresis. Too- low content
of sugar (i.e., below 55%) will result in a weaker, or maybe no, gel formation, whereas
firmness will increase with increasing sugar content. However, too high a sugar content
will cause crystallization of the sugar (Featherstone 2016).
During boiling process of jam making, the added sucrose partly gets converted into
invert sugar. The inversion process is desirable when prepared jams as the reducing
sugars give a shinier appearance to the jam, minimize the crystallization of the sucrose,
stop exudation and reduce the sweetness of the jams. Thus, jams with higher reducing
sugar contents tend to present less crystallization during storage, which is favorable to
the stability of the products (Viana et al. 2014).
4.2.6 Vitamin C
Ascorbic acid is one of the most important nutrients found in mango fruit and acts as
antioxidant, it is important to determine the amount present in a preparation. The
vitamin C content of Apple mango jam is in the range of 17.23-23.99mg/100g which
shows a significant difference (p<0.05) among the main effects as well as the interaction
effect of pH, sugar and pectin levels. The vitamin C in mango jams was reported in the
range of 15.8 - 33.57 mg/100g by previous researchers (Kumar 2008) and the result
obtained in this study is within the range of reported study.
39
During boiling process of jam there is a loss of heat sensitive components. The
reduction of the vitamin C content in mango jam in comparison to the fresh mango is
the result of thermal treatment, which is known to accelerate oxidation of ascorbic acid
to dehydro ascorbic acid, followed by the hydrolysis to 2,3-diketogulonic acid and
eventually polymerization to other nutritionally inactive components (Chuah et al.
2008). Generally, the highest value of vitamin C is observed in the sample prepared
with 3.3pH, 1.5% pectin and 60% sugar. The presence of high amount of pectin, aids
in setting the jam faster since it is jelling agent which as a result also protects the
presence of heat sensitive nutrients of the jam. There are chances of oxidation of
ascorbic acid due high concentration of H+ ions in solution, hence more likely it will
get degrade at low pH (Ndabikunze B, Masambu B, Tiisekwa B 2011).
4.3 Sensory analysis of mango jam
The formulated Apple mango jam with different concentration of pH, pectin and sugar
were subjected to hedonic testing and the mean scores of appearance, color, flavor,
aroma and overall acceptability results are shown in Table 7. There are no significant
(p<0.05) differences in appearance, color, flavor, consistency and over all acceptability
among the samples of jams.
40
Table 8. Sensory evaluation of mango jam
Sam
ple
pH
Pectin
Sugar
Appearanc
e
Flavor
Consistency
color
Overall
acceptability
1
3
1% 50% 4.0±0.11b 4.0±0.43
b 4.0±0.13
a 4.1±0.13
bac 4.0±0.10
ba
2 60% 3.9±0.16cb
4.2±0.10ba
4.0±0.13a 4.1±0.17
ba 3.8±0.42
bc
3 1.5% 50% 3.8±0.17cb
4.0±0.16ba
3.9±0.13a 4.0±0.13
bdc 3.9±0.21
bac
4 60% 3.9±0.17b 4.2±0.14
a 4.0±0.12
a 4.2±0.05
a 3.4±0.18
a
5 0% 50% 3.4±0.08d 3.2±0.05
e 3.16±0.12 3.3±0.33
g 3.1±0.21
d
6 60% 3.3±0.18e 3.1±0.15
ba 3.0±0.08
a 3.0±0.07
a 3.1±0.22
d
7
3.
3
1% 50% 3.8±0.48c 4.1±0.13
ba 4.0±0.30
a 3.9±0.13
d 3.8±0.13
bc
8 60% 4.4±0.29a 4.0±0.26
b 3.7±0.13
b 3.7±0.09
e 3.8±0.13
bac
9 1.5% 50% 4.5±0.299a 3.7±0.22
c 3.6±0.17
b 3.9±0.17
dc 3.9±0.21
bac
10 60% 4.6±0.29a 4.4±0.28a 4.1±0.14
a 3.6±0.18
f 3.9±0.18
bac
11 0% 50% 3.4±0.27d 3.8±0.11
c 3.2±0.16
b 3.8±0.31
e 3.4±0.30
c
12 60% 3.2±0.15e 3.4±0.12
d 3.3±0.15
c 3.1±0.15
h 3.2±0.17
d
• Means values that do not share a letter are significantly different (p<0.05).
4.3.1 Appearance
One of the parameters studied in sensory is visual assessment of product appearance
and color. Appearance plays an important part in helping to select the food product to
consume. Sensory evaluation result indicated the appearance of the jam sample
10(pH3.3, pectin 1.5% and sugar 60%) is judged superior (4.6) whereas sample
12(pH3.3, pectin 0% and sugar 60%) were judged the lowest in appearance with rating
of 3.2. Creaminess, stickiness correlated with pH of the jam. The level of acidity in fruit
pulp is an important aspect in jam processing which has an influence on the gel
formation (Nirmal et al. 2012). According to research the appearance and aroma of
Sapota jam has significant difference based on the amount of pectin added to the
formulation (Azhar and Siddiqui 2015). The lower the pectin is the jam become floody
which ultimately affect jam spread ability and mouth feel and the texture is also affected
by the concentration of pectin (Broomes J 2010).
41
4.3.2 Flavor
Odor and taste of a food together produce its flavor. The perceived flavor of a food
product depends on the type and concentration of flavor constituents within it, the
nature of the food matrix, as well as how quickly the flavor molecules can move from
the food to the sensors in the mouth and nose. In this study sample 10 (pH3.3, pectin
1.5% and sugar 60%) was judged superior in flavor and sample 6 (pH3, pectin 0% and
sugar 60%) was judged the lowest in flavor by panelists. The flavor of the jam is
originated from the fruit and citric acid added to adjust the pH. Some flavor compounds
may be lost during processing, which reduces the intensity of flavor or reveals other
flavor/aroma compounds. The physico-chemical factors determining flavor of jam are
sugar and acidity level. As shown in the table 7, the pH increases from 3 to 3.3 the
sensory acceptability also increases. This result is related with the work of previous
studies that reported an increase in aloevera juice and citric acid resulted in increase in
sensory value of flavor (Karthikeyan.C and Jayabalan.K 2013). The low scores of taste
and mouth feel of jam can be linked to the caramelization during cooking and also due
to hydrolysis of pectin (Fishman, G and Jen 1986).
4.3.3 Consistency
The consistency of sample 10(pH3.3, pectin 1.5% and sugar 60%) was the most
acceptable and sample 6(pH3, pectin 0% and sugar 60%) was judged the lowest in
consistency by panelists. This least score is due to the concentration of the pectin is 0%
and since pectin is used as a thickening agent in jam formulation and thus helps the jam
to set. Therefore, the higher the amount of pectin added in the formulation, the thickest
the jam became which ultimately affects its spread ability and mouth feel. The
consistency of the jam is influenced by gelling agent pectin, sugar and acidity
concentration (Broomes J 2010). Consistency of jam is a parameter that affected by
pectin concentration, processing temperature and sugar added to jam during processing
(Yoo et al. 2009). The creaminess and moist characteristics of jam is correlating with
the acidity therefore acidity also affect the consistency. As reports the consistency
preference of Aloe Vera Jam increased with increases of pectin and citric acid
respectively (Karthikeyan.C and Jayabalan.K 2013).
42
4.3.4 Color
Visual examination by the consumers is important parameter that represents the fitness
of any food for consumption. The same is true for jam for which jam color is one of the
important quality parameters for acceptability. The color of the mango jam is the result
of the presence of natural pigments found in the fruit as well as the milliard reaction
during heating. Among the 12 jam samples sample 4 (pH3, pectin1% and sugar 60%)
had the high acceptability in color by the panelists whereas sample 6(pH3, pectin0%
and sugar 60%) is less acceptable. According to previous studies the sensory value of
color increases with increase in sugar, pectin and citric acid concentration
(Karthikeyan.C and Jayabalan.K 2013). As (Perez-lopez and Antonio Jose 2010; Ya-
Qin et al. 2008) reported that the change in color values are assumed by as a result of
thermal degradation during heat treatment, Millard reaction, enzymatic browning,
ascorbic acid degradation and polymerization of anthocyanins with other phenolic
components.
4.3.5 Overall acceptance
Overall acceptability plays an important role in product development. As observed from
the result the sample 1(pH3, pectin 1% and sugar 50%), judged as the excellent in
overall acceptance. Due to the less amount of pectin added in the jam formulation
sample 5(pH3, pectin 0% and sugar 50%) and 6 (pH3, pectin 0% and sugar 60%) were
judged lower in overall acceptability by panelist. There was significant difference (p =
0.05) between various treatments regarding the overall acceptability of guava and
papaya pulp jam (Gupta.E et al. 2016).
43
5 CONCLUSION AND RECOMMENDATION
5.1 Summery
Physico-chemical properties of six cultivar of Apple, Kent, Keitt, Dodo, Tommy, Local
mango were evaluated. They were evaluated based on their potential suitability for jam
making and Apple mango was found to be more suitable. Apple mango jam prepared
with different quantities of selective ingredients was further evaluated for sensory as
well as physicochemical properties. This study demonstrates that different cultivar of
mango had different physico-chemical characteristics, which qualified them for
different economical, industrial and nutritional utilization.
5.2 Conclusions
Based on the finding from this study, the best variety for jam production is Apple
mango. It is concluded due to its higher total soluble solid content 17.06 oBrix and
excellent pulp yield of 78%. It is known that sugar, pectin and acid are essential in jam
making; the quantities of these ingredients are significantly affects the final quality
characteristics of the final jam. The outcomes of this study suggest that to produce good
quality mango jam, sugar concentration of 60% with the addition of 1.5% pectin with
pH levels of 3.3 is required for produce jam with best sensory acceptable for color,
flavor, taste, texture and overall acceptance and with good physico chemical
composition.
Processing of mango fruit pulp into jam resulted in a significant increase in physico-
chemical properties like TSS and TA. The present results suggest that jam made from
Apple mango variety fruit remain good source of sugar. The sensory evaluation results
indicated that addition of 60% sugar improves over all acceptability of the jam. The jam
balanced to pH 3.3 was acceptable and also sufficient pectin levels (1.5%) was found
superior in consistency, appearance and overall acceptability. Sensory rating of mango
jam indicate that addition of more sugar generally improved the taste and acceptability
of jam
44
5.3 Recommendations
Now a day’s mango jam is consumed commonly, and it is marketed in worldwide.
Therefore, the production of mango jam can create opportunity for domestic and export
markets hence the country’s foreign exchange earnings will increase. It is
recommended that further researches need to be conducted on the following areas:
Different cultivar of mango grown in Ethiopia in fact there are around 1000
mango variety in the world and around 30 cultivar in Ethiopia, those
cultivar needed to be explored for jam production.
There is a lose in vitamin C content during processing of mango jam, so it
should be considered in future studies application of novel food processing
technology for retention of volatile compounds.
Shelf life and storage studies are suggested in further research.
45
REFERENCES
Abdualrahman. 2013. “Physico-Chemical Characteristics of Different Types of Mango
(Mangifera Indica L.) Fruits in Drafur Region and Its Use in Jam Processing.”
Science International 1(5),: 144–47.
Afoakwa.E, Nartey.E, and Ashong J & Annor.G. 2006. “Effect of Sugar, Pectin and
Acid Balance on the Quality Characteristics of Pineapple (.” : 1405–6.
Ahmed, Samia.A.M. 2007. “Quality of Jam Prepared at Home Level.” University of
Khartoum Faculty of Public &Environmental Health Department of Food Hygiene
& Safety Quality.
Ahmmed, Lokonuzzaman, Md Nazrul Islam, and M Saidul Islam. 2015. “A
Quantitative Estimation of the Amount of Sugar in Fruits Jam Available in
Bangladesh.” Journal of Analytical Chemistry 3(5): 52–55.
http://www.sciencepublishinggroup.com/j/sjac.
Ameliaa Jeanroya and karen Ward. 2000. Canning and Preserving for Dummies.
Edition, 2. John Wiley and Sons,Inc.,Hoboken,New Jersey.
Anon. 2000. “Jams and Jellies.” Institutional Distribution, 19(12) : 2: 222–224.
available: http://www.agafruit.com/products.htm%0A.
Anon. 1990. “Mango in India.” Central food technological research Institute (CFRI).
Mysore 570013 (India).: P.22-33.
AOA.C. 2008. “Official Methods of Analysis of AOAC International, 18th Ed;” In
AOAC International, Maryland, USA.
AOAC... 2000. “Official Methods of Analysis of AOAC International,.” In AOAC
International,.
AOAC.. 2000. “Official Methods of Analysis of AOAC International,.” In AOAC
International,.
AOAC. 1999. “Official Method 920.151 Solids (Total) in Fruits and Fruit
Products,Sixteenth Edition, 5th Revision.” In AOAC International,.
AOAC. 2000. “Official Method 942.15 Acidity(Titrable) of Fruit Products, 17th
Edition, Read with A.O.A.C Official Method 920.149 Preparation of Test
Sample,.” In AOAC International,.
Ashaye, OA., Taiwo OO, Adegoke GO. 2006. “Effect of Local Preservatives
(Aframomum Danielli) on the Chemical and Sensory Properties of Stored
Warakanshi.” Afri. J. Agric. Res. 1: 10–16.
Azhar, Iqbal, and Nausheen H Siddiqui. 2015. “Influence of Pectin Concentrations on
46
Physicochemical and Influence of Pectin Concentrations on Physico-.” Journal
of Pharmacy and Pharmaceutical Science 4(May): 68–77.
Baker, Robert A, Norman Berry, Y H Hui, and Diane M Barrett. 2005. “Fruit Preserves
and Jams.”
Basu, S. and Shivhare, U.S. 2013. “Rheological, Textural, Microstructural, and Sensory
Properties of Sorbitol-Substituted Mango Jam.” Food and Bioprocess Technology
6,: 1401–1413.
Bates, Richard Pierce, Justin R Morris, and Philip G Crandall. 2001. Principles and
Practices of Small-and Medium-Scale Fruit Juice Processing. Food & Agriculture
Org.
Bhowmick, N., M.R. Bhanusree M. Preema Devi, and and S.K. Ghosh. 2015.
“Preparation of Value-Added Products Through Preservation.” In Value Addition
of Horticultural Crops: Recent Trends and Future Directions, ed. A.B. Sharangi
and S. Datta. indea: Springer India, 13–39.
Broomes J, Badrie N. 2010. “Effects of Low-Methoxyl Pectin on Physicochemical and
Sensory Properties of Reduced- Calorie Sorrel/ Roselle(Hibiscus Sabdariffa L.)
Jams.” The Open Food Science Journal, 4: 48–55.
Chuah, A.M: et al. 2008. “Effect of Cooking on the Antioxidant Properties of Coloured
Peppers.” Food Chemistry 111: 20 – 28.
Cisneros-Zevallos. 2003. “The Use of Controlled Post Harvest Abiotic Stresses as a
Tool for Enhancing the Nutraceutical Content and Adding Value of Fresh Fruits
and Vegetables.” Journal of Food Science 68: 1560–1565.
CSA. 2014. Agricultural Sample Survey: Report on Area and Production for Major
Crops, Stastical Bulletin 532. Addis Ababa, Ethiopia.
David H. Byrne; 2012. 8 Thickening and Gelling Agents for Food. 1st Ed. Publ.
Blackies Academic and Professional, London:
Degafe.T. 2013. “Fruit and Vegetable Export of Ethiopia: Performance and Constraints.
External Economic Analysis & International Relation Directorate.” National Bank
of Ethiopia, Birritu Quarterly Magazine,Addis Ababa, Ethiopia No 115.
Elias abebe. 2007. “Technical Assessment on Viability of Integrated Fruits Processing
in Ethiopia.” A Thesis Submitted to the School of Graduate Studies of Addis
Ababa University in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Food Engineering.
FAO. 2009. “Utilization of Tropical Foods: Fruit and Leaves. Food and Nutrition Paper,
via Delle Terme Dicaracalla,00100.” Food and Agriculture Organization,
47
STAT accessed July 2009.
FAO. 2002. “Mango, Post-Harvest Operations.” In FAO (Food and Agriculture
Organization of the United States,.
Featherstone, Susan. 2016. “Jams, Jellies, and Related Products.” In A Complete Course
in Canning and Related Processes, Woodhead Publishing, 534.
Fellows, P. and Quaouich, A. 2004. “UNIDO Technology Manual. Small-Scale Fruit
and Vegetable Processing and Products. Production Methods, Equipment and
Quality Assurance Practices United Nations Industrial Development Organization,
Vienna.”
Fellows, Peter John. 2009. Food Processing Technology: Principles and Practice.
Third edit. Woodhead Publishing in Food science ,Technology and nutrition,
Oxford Cambridge New Delhi.
Fishman, G and Jen, F. 1986. Thickning and Gelling Agent for Food 1st Ed. London:
Blackies Academic and professional.
Gebremeskel, Abrehet F. 2018. “Post-Harvest Loss Vs Food and Nutrition Insecurity ;
Challenges and Strategies to Overcome in Ethiopia.” 8(4): 95–102.
Griesbach, Juergen. 2003. World Agroforestry Centre Mango Growing in Kenya. ed.
Anne Marie Nyamu and Tony Simons. nairobi,Kenya: World Agroforestry Centre
(ICRAF). http://www.worldagroforestrycentre.org.
Gupta.E et al. 2016. “Sensory Evaluation and Nutritional Composition of Developed
Papaya-Gooseberry Jam.” Journal of food and nutritional science (June): 600–
608.
Hodges, R. J., J. C. Bubzby, and And B. Bennett. 2011. “Postharvest Losses and Waste
in Developed and Less Developed Countries : Opportunities to Improve Resource
Use.” Journal of Agricultural Science 149: 37–45.
Holly Born and Janet Bachmann. 2006. “Adding Value to Farm Produce: An
Overview.” A Publication of ATTRA - National Sustainable Agriculture
Information Service: 1–12.
Honja, Takele. 2014. “Review of Mango Value Chain in Ethiopia Takele.” Journal of
Biology, Agriculture and Healthcare 4 ,No25(3): 106–15.
Hymavathi, T.V. and Khader, V. 2005. “Carotene, Ascorbic Acid and Sugar Content
of Vacuum Dehydrated Ripe Mango Powders Stored in Flexible Packaging
Material.” Journal of Food Composition and Analysis, 18,: 181–192.
IPMS. 2011. “A Synthesis of IPMS Value -Chain Development Experiences.” IPMS
Ethiopia. http://www.imps-ethiopia.org.
48
Ito, T., Sasaki, K. and Yoshida, Y. 1997. “Changes in Respiration Rate, Saccharide and
Organic Acid Content during the Development and Ripening of Mango Fruit
(Mangifera Indica L. ’Irwin’) Cultured in a Plastic House.” Journal of the
Japanese Society for Horticultural Science 66,: 629–635.
Janice Lawandi. 2015. “Why Do You Have to Add Lemon Juice When Making Jam.”
Jha S, N. et al. 2010. “Quality Parameters of Mango and Potential of Non-Destructive
Techniques for Their Measurement - A Review.” Journal of food science and
technology 47: 1–14.
Jilani, M. S., F. Bibi, K. and Waseem, and M.A. Khan. 2010. “Evaluation of Physico-
Chemical Characteristics of Mango (M. Indica L.) Cultivars Grown in D. I. Khan.
J.” Agric. Res., 48(2): 201–7.
Kader, A A. 2010. “Handling of Horticultural Perishables in Developing vs . Developed
Countries.” In 6th International Postharvest Symposium, ed. M. Erkan and U.
Aksoy. USA, 121–26.
Karthikeyan.C and Jayabalan.K. 2013. “Optimizations Of Ingredients For Sensory
Evaluation Of Aloe Vera Jam Preparation Using Response Surface Methodology.”
International Journal of Engineering Research and Application 3(1): 1224–34.
Kasso, Mohammed, and Afework Bekele. 2016. “Post-Harvest Loss and Quality
Deterioration of Horticultural Crops in Dire Dawa Region , Ethiopia.” Journal of
the Saudi Society of Agricultural Sciences 17(1): 88–96.
Kaur, M., J.S. Bal, L. K. Sharma, and K.S. Bali. 2014. “An Evaluation of Mango
(Mangifera Indica L.) Germoplasm for Future Breending Programme.” Afr. J.
Agric. Res., 9(20): 1530–38.
Kaushik, N., Nadella, T. and Rao, P.S. 2015. “Impact of PH and Total Soluble Solids
on Enzyme Inactivation Kinetics during High Pressure Processing of Mango
(Mangifera Indica) Pulp.” Journal of Food Science, 80,: E2459–E2470.
Khairul, Md. Islam: et al. 2013. “Changes in Acidity, TSS, and Sugar Content at
Different Storage Periods of the Postharvest Mango (Mangifera Indica L.).”
International Journal of Food Science. http://dx.doi.org/10.1155/2013/939385.
Khalid, Khalid Siddig Mohamed Ahmed. 2009. “Suitability of Some Mango(Mangifera
Indica L.) Varieties for Jam Production.” B.Sc. Faculty of Agriculture, Department
of Food Science and Technology University of Khartoum.
Kordylas, J.M. 1990. Processing and Preservation of Tropical and Sub Tropical Foods.
London: Macmillan.
49
Krinsky, Norman and Johnson, Elizabeth J. 2005. “Carotenoid Actions and Their
Relation to Health and Disease.” Molecular aspects of medicine 26: 459–516.
Kumar, Satish. 2008. 125004 “Comparative Studies of Mango Fruit of Different
Cultivars for Processing.” College Of Agriculture Ccs Haryana Agricultural
University.
Larmond.E. 1977. “Laboratory Methods of Sensory Evaluation of Food. Department of
Agriculture, Ottawa, Canada.”
Larrauri, J.A., P. Rupérez, P. Borroto, and F. and Saura-Calixto. 1996. “Mango Peels
as a New Tropical Fibre: Preparation and Characterization.” LWT–Food Science
and Technology, 29: 729–733.
Lee, S. K. and Kader, A. A. 2000. “Preharvest and Postharvest Factors Influencing
Vitamin C Content of Horticultural Crops.” Postharvest Biology and Technology,
20,: 207–220.
Lemmens, L., E. S. Tchuenche, A. M. V. Loey, and M. E. Hendrickx. 2013. “Beta-
Carotene Isomerization in Mango Puree as Influenced by Thermal Processing and
High-Pressure Homogenization.” European FoodResearch Technology 236,:
155–163.
Lunagrown. 2018. “Fruit-Jams-Make-Your-Body-Healthier.” On Wjgk Fox 103.1,.
https://www.lunagrown.com/fruit-jams-make-your-body-healthier/ (reference).
(November 7, 2019).
Malcolum, D. 2005. “Science and Technology of Making Preserves.”
Mbome, Israel Lape. 2008. “Biochemical and Physicochemical Properties of Four
Mango Varieties and Some Quality Characteristics of Their Jams.” Journal of
Food Processing and Preservation 32: 644–55.
Medlicott AP, Thompson AK. 1985. “Analysis of Sugars and Organic Acids in
Ripening Mango Fruits (Mangifera Indica L. Var Keitt) by High Performance
Liquid Chromatography.” J. Sci. Food Agric. 36: 561–566.
Mercadante, A. Z. and Rodriguez-Amaya, D. B. 1998. “Effects of Ripening, Cultivar
Differences, and Processing on the Carotenoid Composition of Mango.” Journal
of Agricultural and Food Chemistry, 46,: 128–30.
Michael, J .Gibney, A. Lanham-new Susan, Cassidy Aedin, and H. Vorster Hester.
2009. Introduction to Human Nutrition,Second Edition. second edi. John Wiley &
Sons Ltd.
Mohammed A.Y. Abdualrahman. 2013. “Physico-Chemical Characteristics of
Different Types of Mango (Mangifera Indica L.) Fruits Grown in Drafur Regions
and Its Use in Jam Processing.” Science International, 1: 144–47.
50
Mohammed, Yakubu A. 2013. “Comparative Analysis of Nutritional and Anti-
Nutritional Contents of Some Varieties of Mango (Mangifera Indica) in Kaduna
Metropolis-Nigeria.” Research Journal of Applied Sciences, Engineering and
Technology 5(4): 387–91.
Muhammad, N: et al. 2012. “Storage Studies of Jam Prepared from Different Mango
Varieties.” Pakistan Journal of Nutrition.
Muralikrishna G, Taranathan RN. 1994. “Characterization of Pectic Polysaccharides
from Pulse Husks.” Food Chem 50: 87–89.
Musyimi, Samson Musembi. 2013. “Production and Characterization of Mango (
Mangifera Indica ) Fruit Wine.” A thesis submitted in partial fulfillment for the
degree of Master of Science in Food Science and Technology at Jomo Kenyatta
University of Agriculture and Technology.
Ndabikunze B, Masambu B, Tiisekwa B, Issa-Zacharia A. 2011. “The Production of
Jam from Indigenous Fruits Using Baobab (Adansonia Digitata L.) Powder as a
Substitute for Commercial Pectin. African.” Journal of Food Science, 5(3): 168–
175.
Nirmal, K. Sinha: et al. 2012. Handbook of Fruits and Fruit Processing. second edi.
John Wiley & Sons Ltd.
Nour, Abdelazim. 2011. “Suitability of Some Sudanese Mango Varieties for Jam
Making.” American Journal of Scientific and Industrial Research 2(1): 17–23.
http://www.scihub.org/AJSIR/PDF/2011/1/AJSIR-2-1-17-23.pdf.
Occena-Po, L.G. 20066. “Mango, and Passion Fruit. In: Handbook of Fruits and Fruit
Processing (Ed. Y.H. Hui),.” Blackwell Publishing, Ames, IA.: 635–650.
Okoth, E M: et al. 2013. “Evaluation of Physical and Sensory Quality Attributes of
Three Mango Varieties at Three Stages of Ripeness , Grown in Lower Eastern
Province of Kenya - Part 1.” Journal of Animal &Plant Sciences 17(3): 2608–18.
Othman, OC and Mbogo, GP. 2009. “Physico-Chemical Characteristics of Storage-
Ripened Mango (Mangifera Indica L.) Fruits Varieties of Eastern Tanzania.”
Tanzania Journal of Science 35,1.
Pearson, D. 1976. The Chemical Analysis of Foods. 7th Edition. Churchill Livingstone,
Edinburgh London and New York.
Perez-lopez, and Antonio Jose. 2010. “Quality of Canned Mandarin as Affected by
Preservation Liquid.” 2009(004253): 1105–13.
Pleguezuelo, C. R. R:, V. H: Zuazo, J. L: Fernández, and and D: Tarifa. 2012. “Physico-
Chemical Quality Parameters of Mango ( Mangifera Indica L .) Fruits Grown in a
Mediterranean Subtropical Climate ( SE Spain ).” Journal of
51
Agricultural Science and thechnology 14: 365–74.
Ranganna, S. 1986. Handbook of Analysis and Quality Control for Fruit and Vegetable
Products. Tata McGraw-Hill Education.
Robert.G and Steel.D. 1980. McGrawHill Publishing Company. Toronto, Canada.
Principles and Procedures of Statistics-A Biometric Approach. Third Edition.
Second Edi. McGraw-Hill International Book Company.
Sabato, S. F, Da Silva, J. M. and da Cruze, J. N. 2009. “Effect of Physical, Chemical
and Sensorial of Irradiated Tommy Atkins Mangoes in an International
Consignment.” Food Control, 120: 284–88.
Salih, Eshtiag Elobied Elsyaid. 2008. 49 “Using Roselle as Natural Colorant In Jam
Making.” A Thesis Submitted in partial Fulfillment for the Degree of Master of
Science in Agricultural.
Shanmugam, PK, G Rangaswami, and EH Gurney. 1992. “Preservation of Fruits and
Vegetables.” Tropical Agriculture 68: 1150–53.
Siddiq, M., S. Akhtar, and R. and Siddiq. 2012. “Mango Processing, Products and
Nutrition. In: Tropical and Subtropical Fruit Processing and Packaging (Ed. M.
Siddiq),.” John Wiley & Sons, Ames, IA.: 277–297.
Ssemwanga, James, Chris Rowlands, and Joseph Kihika Kamara. 2008. “Analysis and
Baseline Status of the Mango Value Chain from Homosha and Assosa to Addis
Ababa.” World vision.
Subramanyam, H., Shantha Krishnamurthy, and And H. A. B. Parpia. 2000. Central
Food Technological Research Institute, Mysore, India Physiology and
Biochemisty of Mango Fruit.
Tharanathan, N.R:, H.M: Yashoda, and T.N: Prabha. 2006. “Mango (Mangifera Indica
L.), ―The King of Fruitsǁ—An Overiew.” Food Reviews International, 22,: 95–
123.
UNCTAD. 2016. “Mango.” In United Nations Conference On Trade And Development,
New York and Geneva: UNCTAD Trust Fund on Market Information on
Agricultural Commodities.
USAD. 2018. Agriculture, United States Department of Service, Agricultural
ResearchNational Nutrient Database for Standard Reference Legacy Basic Report:
19297, Jams and Preserves.
Venkateswarlu, Kambham, and P Siva Krishna Reddy. 2014. “Mango : Carotenoids.”
International Journal of Pharmamedix India 2(2): 741–44.
Viana, E.S. et al. 2014. “Physicochemical and Sensory Characterization of Banana
52
and Araçá-Boi Jam.” Food and Nutrition Sciences 5: 733–41.
Vibhakar, S:, K. V: Nagaraja, J. V: Prabhakar, and H. C: Bhatnagar. 1972.
“Determination of Fruit Pulp Content in Mango (Mangifera Indica) Beverages.”
indian food 26 (2).: 21–26.
WHO. 2006. “Micronutrient Deficiencies Vitamin A Deficiency.”
http://www.who.int/Nutrition/Topics/Vad/En/Index.Html.
Wiersinga, Rolien, and André de Jager. 2007. Identification of Opportunities and
Setting Agenda of Activities in the Ethiopian Fruits and Vegetables Sector.
Ethiopia.
Ya-Qin, Ma et al. 2008. “Phenolic Compounds and Antioxidant Activity of Extracts
from Ultrasonic Treatment of Satsuma Mandarin ( Citrus Unshiu Marc .) Peels.”
: 5682–90.
Yahia.E.M. 1994. “The Potential Use of Insecticidal Atmospheres for Mango,
Avocado, and Papaya Fruits. In: Champ, S.E., Highley, E. and Johnson, G.1. (Eds)
Postharvest Handling of Tropical Fruits.” Australian Centre for lnternational
Agricultural Research (ACIAR) Proceedings 50. ACIAR, Canberra,: 373–374.
Yeshitela, T., Robbertse, P. J. & Stassen, P. J. C. 2005. “Potassium Nitrate and Urea
Sprays Affect Flowering and Yields of ‘Tommy Atkins’ (Mangifera Indica)
Mango in Ethiopia.” South African Journal of Plant and Soil, 22, 1: 28–32.
Yoo, Y.H et al. 2009. “Functional Characterization of the Gels Prepared with Pectin
Methyl Esterase (PME)-Treated Pectin.” International Journal of Biology
Macromolecule 45(3): 226–30.
53
APPENDIX
Appendix A: Physicochemical analysis ANOVA result mango fruit
54
55
56
57
Appendix B: Physicochemical analysis ANOVA result mango jam
58
59
60
61
Appendix C: Sensory evaluation of mango jam
62
63
64
Appendix D: Questioner for Sensory Testing
Date
Panelist number
Sample number
Please rate the coded sample of Apple mango jam how much you like it by putting × mark
across the code
Like
extremely
Like very
much
Like
moderately
Like
slightly
Neither
like nor dislike
Appearance
Flavor
Consistency
Color
Over all acceptability
65
Appendix E: Picture during research work
Produced MangoJam Samples
Sensory analysis for Mango Jam sample
Sensory analysis for mango Jam sample
66
Labrator analysis
![Physico-Chemical Characterization of Keitt Mango …(ratio soluble dry extract/titratable acidity) [12]. Reference reported that [13] there is no direct correlation between the maturity](https://img.pdfslide.us/doc/110x75/5e46a693fdb22a13fb76c7a0/physico-chemical-characterization-of-keitt-mango-ratio-soluble-dry-extracttitratable.jpg)
