Saini
WLȱ valuesȱ increasedȱ withȱ increaseȱ inȱ theȱ uncoatedȱ samples.ȱ Theȱ WLȱinȱ coatedȱ samplesȱ wasȱ
concentrationȱ ofȱ coatingȱ solutionȱ fromȱ 0.5ȱ toȱ 2%,ȱ lessȱ thanȱ theȱ uncoatedȱ sampleȱ whenȱ theȱ sampleȱ
butȱwithȱfurtherȱincreaseȱinȱtheȱconcentrationȱupȱtoȱ wasȱ dippedȱ inȱ theȱ coatingȱ solutionȱ ofȱ 4%ȱ andȱ 5%ȱ
5%,ȱWLȱdecreased.ȱThisȱphenomenonȱwasȱobservedȱ concentrationȱatȱbothȱtheȱdippingȱandȱdryingȱtime.ȱ
whenȱ theȱ pineappleȱ samplesȱ wereȱ dippedȱ inȱ theȱ Theȱ purposeȱ ofȱ increasingȱ theȱ dryingȱ timeȱ wasȱ toȱ
coatingȱ solutionȱ atȱ bothȱ 60ȱ andȱ 120ȱ sȱ followedȱ byȱ developȱ anȱ effectiveȱ coatingȱ onȱ theȱ fruitȱ sample,ȱ
ovenȱdryingȱforȱbothȱ10ȱandȱ40ȱmin.ȱTheȱmaximumȱ butȱ theȱ increaseȱ inȱ theȱ dryingȱ timeȱ didȱ notȱ yieldȱ
valueȱofȱWLȱwasȱobservedȱatȱaȱconcentrationȱofȱ2%ȱ coatingȱtoȱsupportȱincreaseȱinȱWL.ȱWhenȱtheȱovenȱ
irrespectiveȱ ofȱ dippingȱ andȱ dryingȱ time.ȱ Thisȱ mayȱ dryingȱ timeȱ wasȱ increasedȱ fromȱ 10ȱ toȱ 40ȱ min,ȱ theȱ
beȱdueȱtoȱtheȱreasonȱthatȱanȱoptimumȱconcentrationȱ
valueȱofȱWLȱvariedȱfromȱ39.18ȱtoȱ47.91ȱ(g/100ȱgȱfreshȱ
ofȱcoatingȱsolutionȱmayȱresultȱintoȱeffectiveȱcoating,ȱ
sample)ȱ afterȱ dippingȱ theȱ sampleȱ forȱ 60ȱ sȱ inȱ theȱ
whichȱ mayȱ causeȱ anȱ increasedȱ WL.ȱ Subsequentȱ
coatingȱ solutionȱ ofȱ concentrationȱ rangingȱ fromȱ 0.5ȱ
increaseȱinȱtheȱconcentrationȱmayȱresultȱinȱtheȱpoorȱ
toȱ5%.ȱTheȱWLȱvariedȱfromȱ37.50ȱtoȱ48.86ȱ(g/100ȱgȱ
attachmentȱofȱcoatingȱorȱcharacteristicȱchangesȱinȱtheȱ
freshȱsample)ȱasȱtheȱdippingȱtimeȱwasȱincreasedȱtoȱ
membraneȱproperties.ȱInȱtheȱresults,ȱitȱwasȱobservedȱ
120ȱs.ȱThisȱmayȱbeȱdueȱtoȱtheȱreasonȱthatȱincreasingȱ
thatȱfurtherȱincreaseȱinȱtheȱconcentrationȱaboveȱ2%ȱ
theȱovenȱdryingȱtimeȱcausedȱdecreasedȱWLȱduringȱ
probablyȱ ledȱ toȱ poorȱ formationȱ ofȱ coating,ȱ whichȱ
OD,ȱ dueȱ toȱ shrinkageȱ inducedȱ byȱ longerȱ drying.ȱ
resultedȱinȱdecreasedȱWL.
Theȱ longerȱ ovenȱ dryingȱ timeȱ isȱ generallyȱ usedȱ forȱ
WLȱ valuesȱ ofȱ coatedȱ samplesȱ treatedȱ withȱ coatingȱ solidifyingȱtheȱcoatingȱlayer,ȱwhichȱmayȱdamageȱtheȱ
solutionȱ rangingȱ fromȱ 0.5ȱ toȱ 3%ȱ wereȱ moreȱ thanȱ pineappleȱ tissuesȱ byȱ changingȱ theȱ cellȱ membraneȱ
theȱ uncoatedȱ orȱ controlȱ sample,ȱ whereȱ asȱ valuesȱ structureȱthatȱreducedȱtheȱmassȱtransferȱrateȱduringȱ
ofȱsamplesȱcoatedȱatȱ4%ȱandȱ5%ȱwereȱlessȱthanȱtheȱ ODȱprocess.ȱTheȱpineappleȱtissues,ȱdriedȱforȱ10ȱminȱ
uncoatedȱsamples.ȱThisȱphenomenonȱwasȱobservedȱ wereȱobservedȱtoȱmaintainȱtheirȱfirmȱcellȱstructureȱ
atȱbothȱtheȱdippingȱtimeȱofȱ60ȱandȱ120ȱsȱandȱlaterȱovenȱ duringȱOD.ȱTherefore,ȱincreaseȱinȱtheȱovenȱdryingȱ
driedȱforȱbothȱ10ȱandȱ40ȱmin.ȱTherefore,ȱincreasingȱ timeȱfromȱ10ȱtoȱ40ȱminȱledȱtoȱdecreaseȱinȱWL.ȱThisȱ
theȱconcentrationȱtoȱ4%ȱandȱaboveȱresultedȱlesserȱWLȱ isȱinȱagreementȱwithȱpreviousȱresearchȱfindingsȱonȱ
thanȱtheȱuncoatedȱsamples.ȱThisȱmayȱbeȱattributedȱ
lowȱmethoxylȱpectinateȱ(LMP)ȱinȱpotatoesȱ(Khinȱ et al .ȱ
toȱtheȱfactȱthatȱhighȱconcentrationȱofȱcoatingȱagentȱ
2006a).ȱLenartȱandȱDabrowskaȱ(2001)ȱreportedȱthatȱ
resultedȱinȱmoistureȱbarrierȱduringȱOD.ȱTherefore,ȱ
LMPȱcoatedȱsamplesȱhaveȱgreaterȱWLȱthanȱuncoatedȱ
increasingȱ theȱ concentrationȱ ofȱ coatingȱ solutionȱ toȱ
samplesȱ withȱ variousȱ dryingȱ andȱ osmoticȱ time.ȱ
4%ȱ orȱ aboveȱ didȱ notȱ yieldȱ anyȱ significantȱ results.ȱ
LenartȱandȱDabrowskaȱ(1999)ȱalsoȱreportedȱthatȱLMPȱ
Coatingȱ treatmentȱ priorȱ toȱ ODȱ mayȱ beȱ consideredȱ
asȱaȱcoatingȱagentȱinȱapplesȱcouldȱachieveȱhigherȱorȱ
asȱaȱstructuralȱmodificationȱtoȱfoodȱcellȱmembranesȱ
sameȱWLȱthanȱuncoatedȱsamples.ȱStatisticalȱanalysisȱ
dueȱ toȱ itsȱ abilityȱ ofȱ enduranceȱ duringȱ OD.ȱ Theȱ
revealedȱ significantȱ differencesȱ (p<0.05)ȱ amongȱ
developmentȱofȱcoatingȱwouldȱresultȱinȱhigherȱWLȱ
theȱdataȱforȱuncoatedȱandȱcoatedȱsamplesȱoverȱsixȱ
andȱimpedimentȱofȱsucroseȱuptake.
differentȱ concentrations,ȱ twoȱ dippingȱ timeȱ andȱ
Consideringȱ theȱ meanȱ valuesȱ ofȱ WLȱ atȱ bothȱ theȱ twoȱovenȱdryingȱtime.ȱTheȱvalueȱofȱWLȱatȱbothȱtheȱ
dippingȱandȱdryingȱtime,ȱthereȱwasȱanȱincreaseȱinȱ dippingȱtimeȱ(60ȱandȱ120ȱs)ȱandȱdryingȱtimeȱ(10ȱandȱ
WLȱasȱtheȱconcentrationȱwasȱincreasedȱfromȱ0.5ȱtoȱ 40ȱmin)ȱwereȱfoundȱstatisticallyȱdifferentȱfromȱeachȱ
2%ȱandȱthenȱdecreasedȱasȱitȱwasȱfurtherȱincreasedȱ otherȱ(p<0.05).ȱTheȱWLȱvaluesȱofȱtheȱcoatedȱsamplesȱ
toȱ 5%.ȱAtȱ allȱ theȱ concentrations,ȱ WLȱ decreasedȱ byȱ wereȱstatisticallyȱdifferentȱfromȱtheȱuncoatedȱsample.
increasingȱtheȱovenȱdryingȱtimeȱfromȱ10ȱtoȱ40ȱminȱ
atȱbothȱtheȱdippingȱtimeȱofȱ60ȱandȱ120ȱs.ȱTheȱmeanȱ Solid Gain
valuesȱ ofȱ WLȱ inȱ coatingȱ solutionȱ ofȱ concentrationȱ
Theȱsolidȱgainȱ(SG)ȱinȱcoatedȱandȱuncoatedȱpineappleȱ
rangingȱfromȱ0.5ȱtoȱ3%ȱwereȱmoreȱthanȱtheȱvalueȱofȱ
samplesȱatȱvariousȱconcentrationsȱofȱpectinȱandȱtwoȱ
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