ONION LOSSES DURING STORAGE AS INFLUENCED BY CURING METHOD

8/11/2019 ONION LOSSES DURING STORAGE AS INFLUENCED BY CURING METHOD

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ONION LOSSES DURING STORAGE AS

INFLUENCED BY CURING METHOD

Adel H. Bahnasawy*

Agric. Mechanization DepartmentMoshtohor Agric. College

Zagazig University-Benha Branch

Toukh-Qaliouia - !gypt

ABSTRACT

The main aim of this work was to study the effect of curing methods on the onion

losses during storage. Onions were cured using four methods as follows: (a) field curing

for 11 days (traditional), (b) solar drying for three days, (c) artificial curing (emergency

curing) at 455! o" for 1! hours and (d) no curing. Onion losses at the end of curing

#rocess were determined for each method. The cured onions were stored at (a) room

tem#erature ($5$% o" and 45%5& ') and (b) low tem#erature (4 o" and 5*!&

'). The losses of onion were determined at inter+als during the storage #eriod. The

results indicated that the highest losses (4 &) were recorded when the onion cured at the

o#en field for 11 days, followed by solar drying treatment ($.5 &) and the lowest losses

were $& for the artificial curing treatment at the end of curing #rocess. -uring storage,

there were no significant differences in moisture losses for all treatments of curing under

both storage conditions. The total losses recorded during storage #eriod for the onion at

room conditions were higher than those of cold storage conditions for all curing

treatments. The highest total losses were recorded for no curing treatment, followed by

solar curing treatment under room conditions storage, while the lowest losses were

recorded for the field curing treatment. There was no onion s#routing until the end of

e#eriment when onion was stored at room conditions, while by the second month, onionstarted to s#rout under cold storage conditions and increased by the end of e#eriment.

The highest s#routing #ercentage was recorded for the field curing treatment (1.1%&).

Keyw!ds"

Onion curing / tem#erature / 'elati+e humidity / 0eight losses rtificial

curing / 'oom tem#erature.

*2ecturer of gricultural 3ngineering, oshtohor ac. Of gric., 6aga7ig 8ni+., 9enha 9ranch,oshtohor, Toukh 3gy#t tel $!145! fa $!14%**%email: bahnasawyadel;hotmail.com


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INTRODUCTION

The onion (Allium cepa) is usually cured after har+esting to allow the in


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Outside air may be used for onion curing or the air may be artificially heated to $4

$.5o" if outside air was too cool or humid. or this added curing #eriod about

$5!!!cmFsec of air #er m of onions is usually ade>uate. -uring this forced +entilation,

the bulbs should lose 5& of their #restorage weight, the neck should become dry and

the outer scales brittle. O+ercuring will cause ecessi+e loss of outer scales and ecessi+e

humidity or tem#erature during curing may cause staining the outer scales. "ondensation

on the onion should be a+oided ('yall and 2i#ton, 1%).

The main aim of this work was to study the effect of curing methods on the onion

losses during storage. The s#ecific ob


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were taken randomly to measure the a+erage #olar and e>uatorial diameters, neck diameter,

neck length, the a+erage weight and the initial moisture content of bulbs before storing. These

were 4.H!.!* cm, 4.H!.%4 cm, 1.1H!.cm, 1.5H!.45cm, 1!H. g and *.5H$.4 & (w.b.),

res#ecti+ely.

The C%!&n' B&n

The curing bin, in which the onion bulbs were #laced during the curing #rocess, was

constructed from steel co+ered with #lastic. The length, width and height of the bin

(F&'%!e1) were !.5, !.5, and 1.! m, res#ecti+ely. The bin frame was made from 4cm

4cm steel angles. The bin was di+ided into 4 shel+es.

Hea(ed A&! )!&n' Sys(e+

The heated air forced system consisted of a blower, heated air source and main duct.

blower of maimum #ressure 5m and maimum +acuum is *m, working on $$!+, 5!7, ma.

discharge is 1.4 mFh and $*5! r#m (=nternational, odel O9!) was used to #ro+ide the

heated air. =t was o#erated using a !.5 h#, electric motor.

Meas%!e+en(s

,. D!y-B%l Te+/e!a(%!e

digital scanning thermocou#le (=@O I3E-O' "3'T==3- !!1 "at. Eo. $*!!

Eew ?ork, 8@) was used to measure the tem#erature at +arious locations in the onion

curing bin as well as the ambient tem#erature. control board was constructed to record

the tem#erature readings using a number of switches e>uals to the number of

thermocou#le sensors. Thirteen thermocou#le sensors (Ty#e T, "at. Eo. 3!*5!!%4,

anwell, 2ondon, 8J) were located at +arious #ositions of the curing bin and one

thermocou#le sensor was used to measure the ambient air tem#erature.

0. Rela(&1e H%+&d&(y

Thermohydrometer (@igma == odel E@==G Ty#e Eo. %$1!.!! @J @TO

J3='?OJ= C. "O., 2T Tokyo KAE) was used to record the relati+e humidity

in the curing bin as well as the ambient relati+e humidity of the air surrounding the bin.


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igure 1. -iagram showing the curing bin and the heated air blower.

@helf 1

@helf

@helf

$

@helf 4

eated

ir ir 9lower


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2. M&s(%!e Cn(en(

@am#les were taken weekly to determine the moisture loss. Onion sam#les were weighed

before and after drying. Onion sam#les were dried using drying o+en at 1!5 o" until a

constant weight was obtained according to O" (1).

3. On&n De(e!&!a(&n

The stored onions were ins#ected monthly to determine the #ercent of deterioration.

The s#oiled onions were weighed and the accumulati+e #ercentage of deterioration was

determined (from the original weight of the onion).

ESULTS

AND

D

ISCUSSION

,. C%!&n'"

,.,. A!(&)&&al C%!&n'"

F&'%!e 0shows the recorded tem#eratures of ambient air and onion bulbs, relati+e

humidity, and onion weight losses at different bin shel+es for the artificial curing #rocess. =t

indicated that the tem#erature (ranged from 455! o") decreased from the bottom towards to

the to# of the curing bin and the re+erse was ha##ened for the relati+e humidity +alues

(ranged from $545&). The highest weight losses were recorded for the onion at the first

shelf (.!&) followed by the second, third and fourth shelf ($.4, 1.5 and !.4 &

res#ecti+ely). This was due to the higher tem#erature and lower relati+e humidity, which

was the main characteristics of the air incoming to the curing binB moreo+er, the air +elocity

was higher at the entrance than those at the other shel+es.

,.0. Sla! C%!&n'"

F&'%!e 2shows the effect of tem#erature and relati+e humidity on the weight losses

of the onion during the solar curing #rocess. The results indicated that the weight losses

increased for the onion on the to# of the bin because they were e#osed directly to the sun

beside the black sheet was acting as a solar collector. =t indicated also that the tem#erature

decreases from the bottom of the bin to the to# of it and the re+erse was ha##ened for the

relati+e humidity +alues. The weight loss #ercent from the onion increased as we go

u#ward in the onion bin, this was due to the solar radiation affects the first layers facing the

sun more the followed layers.


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,.2. F&eld C%!&n'

Onions were left on the o#en field for 1! days as it is usually #racticed by the 3gy#tian

farmers. F&'%!e 3shows the effect of tem#erature and relati+e humidity on the weight

losses of the onion during the curing #rocess. Onion weight losses increased with the time

of curing. The results indicated that the a+erage onion surface tem#erature during the

daytime ranged from $!5! o" and the a+erage ambient tem#erature ranged from $!5 o".

The ambient relati+e humidity ranged from !!& during the day and night times.

t the end of curing #rocess, the a+erage onion weight losses for the different curing

treatments were shown inF&'%!e 4. =t shows that the highest losses (4&) were recorded for the

onion which was cured at the o#en field for 11 days followed by the solar cured onion ($.5&)

and the lowest #ercentage ($&) was recorded when the onion bulbs were cured artificially for

1! hours. The results indicated that the losses of the onion that recei+ed a field curing were as

twice as of the artificial curing treatment, this maybe due to the curing #eriod of field curing

was longer than those of the other curing methods, also there was high fluctuation of the

ambient conditions around the field cured onions.

0. On&n lsses d%!&n' s(!a'e

0.,. M&s(%!e lsses

F&'%!e 5shows the accumulati+e moisture losses during storage #eriod at room

conditions as influenced by methods of curing. 9y the first 4 weeks, the highest losses

($.5 &) were recorded for the onion, which cured using solar radiation while the lowest

losses ($.1 &) were recorded for the onion, which cured artificially. 9y the end of storage

#eriod, the highest moisture losses (*.% &) were recorded for the onion which cured at the

field while the lowest losses (.41&) were recorded for the onion which did not recei+e any

curing.

F&'%!e 6shows the accumulati+e moisture losses during storage #eriod at cold

storage conditions as influenced by methods of curing. fter the first 4 weeks, the highest

losses (1.4 &) were recorded for the onion, which did not recei+e any kind of curing while

the lowest losses (1. &) were recorded for the onion which cured at the field because the

trans#iration coefficient of the cured onion is substantially less than those of the uncured

commodities (Ian der 9erg and 2ent7, 1%1). 9y the end of storage #eriod, the highest

losses (*.55 &) were recorded for the onion, which cured at the field while the lowest


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losses (.$4 &) were recorded for the onion, which cured using the solar radiation.

Cenerally, the moisture losses ranged from .4*.& for all curing treatments under both

room and cold storage conditions, these results agreed with those obtained by 9oyette et al.

(1$).

0.0. T(al On&n Lsses"

F&'%!es 7 and 8show the total accumulati+e onion losses under both room and cold

storage conditions for the onion curing treatments. t room conditions, the lowest losses

(1.&) were recorded when the onion recei+ed field curing while the highest losses

(1.15&) were recorded when the onion was cured using solar radiation for three days. t

cold storage, the lowest losses (*.!&) were recorded when the onion recei+ed field curing

while the highest losses (1$.5&) were recorded when the onion did not recei+e any kind of

curing. =t indicated also that there were no significant differences in the total losses

between the onion, which recei+ed artificial, field or solar curing.

Cenerally, the total losses recorded at all curing treatments when the onion stored at

room conditions were higher than those stored at cold storage conditions. =t was higher by

. & for the artificial curing treatment, *.*5& for the solar curing, 4.4& for the field

curing and .& for the nocuring treatment.

0.2. On&n s/!%(&n' a( ld s(!a'e

Eo s#routed onion bulbs were obser+ed for the onion, which stored at room

conditions during the entire storage #eriod. 9ut at cold storage the onion started to s#rout

after the second month of storage for the all curing treatments as shown in F&'%!e ,9. =t

indicated that the onion which cured at the field recorded the highest #ercent of s#routed

bulbs (1.1%&), followed by the onion which cured by solar radiation (.5&), followed by

the onion which did not recei+e any curing (%.$&) and the lowest #ercentage (%.&) was

recorded for the onion which cured artificially.

Conclusions

1. The artificial curing was a fast and safe method for onion curing before storage but stillis an added e#ense to the onion #roduction. The moisture losses were higher for the


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onion at the shel+es which facing the heated air stream. rtificial curing tem#erature

ranged from 455! o" and the relati+e humidity +alues ranged from $545 &.

$. @olar curing is less e#ensi+e as com#ared with the artificial curing which allows the

solar radiation to dry onion faster than the field curing in addition to the onion is

#rotected from the direct solar radiation. The moisture losses were higher for the onion

at the shel+es which facing the sun radiation.

. The field curing is the least e#ensi+e of all curing methods but it recorded the highest

#ercentage of losses during the curing #rocess, storage as well as the highest s#routing

&.

4. -uring storage, there were no significant differences in moisture losses for all

treatments of curing under both storage conditions. The total losses recorded during

storage #eriod for the onion at room conditions were higher than those of cold storage

conditions for all curing treatments.

5. The highest total losses were recorded for the solar curing treatment, followed by no

curing treatment under room conditions storage, while the lowest losses were recorded

for the field curing treatment.

. The highest total losses were recorded for no curing treatment, followed by solar

curing treatment under room conditions storage, while the lowest losses were recorded

for the field curing treatment.

%. There was no onion s#routing until the end of e#eriment when onion was stored at

room conditions, while by the second month, onion started to s#rout under cold storage

conditions and increased by the end of e#eriment.

*. The highest s#routing #ercentage was recorded for the field curing treatment (1.1%&).

Re)e!enes

O". 1. Official ethods of nalysis, 1th3d. ssociation of Official nalytical

"hemists. 0ashington -. ".

arrow, J.. and @. arris. 1. rtificial curing of onions for control of neck rot

(Botrytis allii). E.6.K. gric. 'es., 1$:5$!4.

non. 1*. =nternational @tandards =@OF-=@ 1%.

9ondare+a, I.@. 1%4. ethods of #artial drying of onions during the storage in warehouses

with acti+e +entilation. Jonser+naya O+oshchesushilDnaya, %, 11%.


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9oyette, . -., -.". @anders and 3. . 3stes. 1$. Aosthar+est cooling and handling of

onions. Aubl., C41. 'aleigh, E. ".: Eorth "arolina "oo#erati+e 3tension

@er+ice, Eorth "arolina @tate 8ni+ersity.

9uchanan, 2. ". 1. "ontrol of 9otrytis neck rot of onions in bulk curing and storage

facilities. "anadian =nstitute of ood Technology Kournal, , 1$1$.

9uffington, -.3. and Custshaw, K.". Kr. 1%. @tability of onions as influenced by +acuum

curing and storage in three different en+ironments. Aroceedings of the lorida

orticultural @ociety, **, 54$5.

-D?chenko, I.@. 1%. 'eduction in losses during storage of onions. Jartofel = -+oshchi,

1!, %*.

2e#ori, 0, 9rown, ". and 2ee#er, A. 1%!. "onditioning onions in a mechani7ed #roduction

system. Kournal of the 'io Crande Ialley orticultural @ociety, $4, 1!511.

arino+, @., Ilko+, C., Ilche+, C. and 8ko+, T. 1%. =nitial e#erience with storage of

onions with acti+e +entilation. 9Dlgarski Alodo+e 6elenchutsi = Jonser+i, , 115.

aw, 9. 0., -. . @mittle and 9. C. ullini. 1%. rtificially curing sweet onions.

##lied 3ng. =n griculture, 1(4):51%5$!.

'yall, . 2. and 2i#ton 0. K. 1%. andling, trans#ortation and storage of fruits and

+egetables. Iolume 1, @econd 3dition. Iegetables and elons. I=. Aublishing co.,

=E".0est#ort, "onnecticut. =@9E !*%!55115 (+.1, $nd ed.).

@mittle, -. . and '. 3. 0illiamson. 1%*. Onion #roduction and curing in Ceorgia.

'esearch 'e#ort $4*. Kune. Tifton, Ca. 8ni+ersity of Ceorgia.

Thamai7harasi, I. and Earasimham, A. 1. Crowth of Spergillus nigeron onion bulbs and

its control by heat and sul#hur dioide treatments. Tro#ical @cience, , 4555.


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ONION LOSSES DURING STORAGE AS INFLUENCED BY CURING METHOD