Handling and preservation of fruits and vegetables by combined methods for rural areas : technical manual

107 Pages·2003·3.4 MB·English

by  Barbosa-Cánovas, Gustavo V

Handling and preservation FAO
AGRICULTURAL
SERVICES
offruits and vegetables BULLETIN
bycombined methods
for rural areas
Technicalmanual
OsmoticSolution
Sugar
Citricacid Waterflux
Potassiumsorbate
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Solutesflux
Handling and preservationof AGRICULTUFRAAOL
SERVICES
fruitsandvegetables BULLETIN
bycombined methods 149
forruralareas
Technicalmanual
by
GustavoV.Barbosa-Canovas
JuanJ.Fernandez-Molina
StellaM.Alzamora
MariaS.Tapia
AurelioLopez-Malo
JorgeWeltiChanes
This On©
FOODANDAGRICULTUREORGANIZATIONOFTHEUNITEDNATIONS
Rome,2003
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ISBN92-5-104861-4
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©FAO2003
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FOREWORD
Fruitsandvegetablesarcnutritious,valuablefoodsfullofflavour.However,inthelow-income
countries,poorcareandhandlingofthesecropsfrequentlyresultsinlossofquality,especially
whennotconsumedimmediately.Inthesecountries,peoplearenotsufficientlyinformedon
howtomaketechnicalchoicesforbetterpreservationoffruitsandvegetables.Thismanualon
handlingandpreservationoffruitsandvegetablesbycombinedmethodshasbeenpreparedin
responsetoneeds,bothrealandperceived,thatsurpluscropcanbeused.
Themanualistheresultofcontributionsfromaselectionofdifferentauthors,mainlyfrom
countriesinLatinAmerica.Itcontainsbasicconceptsandoperationsofprocessing,whichare
essentialforabetterunderstandingandcomprehensiveapproachtotheapplicationofthe
combinedmethodstechnology.Somepracticalexamplesarcdescribedstepbystep,including
calculationsandproceduresrequiredtosetupthistechnologyelsewhere.Likewise,itincludes
examplesofmodemprocessingtechniquesrequiredtomeetthehighstandardsofqualityand
hygieneforfoodproduction.
Thismanualisdividedintofivechapters.Chapteronepresentsaglobaloverviewontrading
infruitsandvegetables,itshowstrendsinconsumptionandconsiderssomeofthesocio-
economicissuesinvolvedinthecontextofpostharvestfoodlossesespeciallyduring
processingandstorage.Chaptertwodescribessomeconceptsofharvestingandpostharvest
handling,storageandpestcontrol.Chapterthreefocusesontheimportanceoftheconceptof
wateractivities(aw),andtheirroleinfoodpreservation.Similarly,itdescribestheconceptof
intermediatemoisturefoods(IMF)andthecombinedmethodspreservationtechnologyfor
fruitsandvegetables.Chapterfourismostlyconcernedwithfruits,anddescribestheextension
oftheintermediatemoistureconcepttoproductscontaininghighmoisture.Thechapter
includesthemainpreliminaryoperationsandformulations.Thisincludespackaging,transport,
storage,useoffruitspreservedbycombinedmethodsandqualitycontrol. Chapterfive
concentshorticulturalcropsand.inadditiontosomepreliminaryoperations,describesa
numberofcombinedoptionaltreatmentssuchasirradiation,refrigeration,pickling,and
packaging,transportandqualitycontrol.
Fruitsandvegetablesrepresentanimportantandinmanycasesanunder-appreciatedresource
whichcouldbenefitfrombetterutilisationandexploitationintheruralcommunities.This
manualhasthereforebeendesignedasausefulreferencebookforfoodproducers,tradersand
processors.Otherusersincludeextensionagentsandruraldevelopmentpractitionersactivein
theprocessingandpreservationaspectsofthefoodchain.
GeoffreyC.Mrenia
Director
AgriculturalSupportSystemsDivision
FrxxlandAgricultureOrganization
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ACKNOWLEDGEMENTS
TheauthorsappreciateandacknowledgeDr.DaniloJ.Mejia,OfficerofAgriculturalandFood
EngineeringTechnologiesService(AGST,FAO,Rome),notonlyfortheTableofContentshe
proposedtotheauthors,butalsoforhisinvaluablehelpthroughoutthegenerationandediting
ofthismanual.TheauthorsalsowanttoacknowledgetheCYTED(Ibero-AmericanProgram
toPromoteScienceandTechnology),SubprogramXIformanyyearsofsupportindeveloping
andpromotingthecombinedmethodstechnologyforfruitsandvegetables,aswellasother
commodities.
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9
HANDLINGANDPRESERVATIONOFFRUITSANDVEGETABLESBY
COMBINEDMETHODSFORRURALAREAS
INTRODUCTION 1
CHAPTER1ESRO1CIIIOI-SEACNODNVOEMGIECTAALBLAENSD;TAENCHONVIECRAVLIEIMSLSUOENS 2
1.1 Tradeandglobaltrends:Fruitsandvegetables 3
1.2 Traditionalconsumption 4
1.3 Economicandsocialimpact 4
11.45 CPoosmtm-ehrarcvieasltcloonssstersaainntdsresourceunder-utilizationindevelopingcountries 65
1.5.1 Foodlossesafterharvesting 6
1.5.2 Foodlossesduetosocialandeconomicissues 2
1.6 Pre-processingtoaddvalue 8
1.7 Pre-processingtoavoidlosses 8
1.8 Alternativeprocessingmethodsforfruitsandvegetablesinruralareas 8
1.8.1 Scaldingorblanchinginhotwater 10
1.8.2 Coolingintrays 10
1.8.3 Sulphiting 10
1.8.4 Sundryingandosmoticdehydration 10
1.8.4 Fermentation II
1.8.6 Storage 14
1.8.7 Samplecalculationforadjustingfruitsolublesolidsandacidcontents 16
CHAPTER2BASICHARVESTANDPOST-HARVESTHANDLING
CONSIDERATIONSFORFRESHFRUITSANDVEGETABLES L
2.1 Harvesthandling 19
2.1.1 Maturityindexforfruitsandvegetables 19
2.1.2 Harvestingcontainers 26
2.1.3 Toolsforharvesting 26
2.1.4 Packinginthefieldandtransporttopackinghouse 26
2.2 Post-harvesthandling 29
2.2.1 Curingofroots,tubers,andbulbcrops 29
2.2.2 Operationspriortopackaging 30
2.2.3 Packaging 31
2.2.4 Coolingmethodsandtemperatures 33
2.2.5 Storage 35
2.2.6 Pestcontrolanddecay 37
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CHAPTER3GENERALCON.SIDF.RATIONSFORPRESERVATIONOFFRUITS
AM)VEGETABLES 32
3.1 WaterActivity(a,„)conceptanditsroleinfoodpreservation 39
3.1.1 awconcept 39
3.1.2 Microorganismsvi.awvalues 39
3.1.3 Enzymaticandchemicalchangesrelatedtoa„,values 40
3.1.4 Recommendedequipmentformeasuringaw 4'
3.2 IntermediateMoistureFoods(IMF)concept 44
3.2.1 FruitspreservedunderIMFconcept 45
3.2.2 AdvantagesanddisadvantagesofIMFpreservation 45
3.3 Combinedmethodsforpreservationoffruitsandvegetables:apreservationconcept 46
3.3.1 Whvcombinedmethods? 46
3.3.2 Generaldescriptionofcombinedmethodsforfruitsandvegetables 46
3.3.3 Recommendedsubstancestoreduce infruits 48
3.3.4 RecommendedsubstancestoreducepH 50
3.3.5 Recommendedchemicalstopreventbrowning 51
3.3.6 Recommendedadditivestoinhibitmicroorganisms 51
3.3.7 Recommendedthermaltreatmentforfoodpreservation 52
CHAPTER4F.XTKNSIONOlTHEINTKRMF.niATF.MOISTURECONCEPTTO
HIGHMOISTUREPRODUCTS 55
4.1 Preliminaryoperations 56
4.2 Desiredawandsyrupformulation 57
4.2.1 Calculusrequired 57
4.2.2 Watercontentvs.a„.relationship 59
4.3 Exampleofapplication 60
4.4 Packagingmethodsforminimallyprocessedproducts 74
4.4.1 Packagingwithsmallunits 74
4.4.2 Transportingthepackage 74
4.4.3 Loadingpackagingunits 74
4.4.4 Vacuumandmodifiedatmospherepackaging 74
4.5 Transport,storageanduseoffruitspreservedbycombinedmethods 75
4.5.1 Openvs.refrigeratedvehicles 75
4.5.2 Unloading 75
4.5.3 Storagetemperaturevs.shelflife 75
4.5.4 Repackagingconsiderations 79
4.5.5 Syrupreconstitutionandutilization 79
4.5.6 Optimalutilizationoffinalproducts 79
4.6 Qualitycontrol 79
4.6.1 Recommendedmicrobiologicaltests 79
4.6.2 Nutritionalchanges 80
4.6.3 Changesinsensoryattributesandacceptability 80
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CHAPTER5PROCEDURESFORVEGETABLESPRESERVEDBYCOMBINED
METHODS 83
5.1 Preliminaryoperations 83
5.2 Combinedoptionaltreatments 86
5.2.1 Irradiation 86
5.2.2 Refrigeration 87
5.2.3 Modifiedatmosphere 88
5.2.4 Pickling 89
5.2.5 Fermentation 90
5.3 Packagingmethods 91
5.3.1 Plasticcontainersandbags 91
5.3.2 Vacuumpackaging 91
5.3.3 Modifiedatmospherepackaging 91
5.4 Transport,storageanduseofvegetablespreservedbycombinedmethods 92
5.4.1 Openvs.refrigeratedvehicles 92
5.4.2 Unloading 92
5.4.3 Storagetemperaturevs.shelflife 93
5.4.4 Repackagingconsiderations 93
5.4.5 Optimalutilizationofthefinalproducts 93
5.5 Oualitvcontrol 95
5.5.1 Recommendedmicrobiologicaltests 95
5.5.2 Nutritionalchanges 95
5.5.3 Changesinsensoryattributesandacceptability 95
References 97
Glossary 99
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INTRODUCTION
Thismanualpresentsinformationrelatedtotheprocessingoffruitsandvegetablesby
combinedmethods.Itisintendedtoserveasaguidetofarmersandprocessorsoffruitsand
vegetablesinruralandvillageareas.Informationconcerningthetradeandproductionoffruits
andvegetablesindifferentcountriesisprovided,aswellasinformationontheprocessingof
fruitandvegetableproducts.Thecombinationoffactorssuchaswateractivity(aw),pH.redox
potential,temperature,andincorporationofadditivesinpreservingfruitsandvegetablesis
important,andallplayacrucialroleinimprovingtheshelflifeoffreshandprocessed
commodities.
Theincreasingpopularityofminimallyprocessedfruitsandvegetableshasresultedingreater
healthbenefits.Furthermore,theongoingtrendhasbeentoeatoutandtoconsumeready-to-
eatfoods(Alzamoraetal..2000).Withthisincreasingdemandforready-to-eat.fresh,
minimallyprocessedfoods,includingprocessedfruitsandvegetablespreservedbyrelatively
mildtechniques,newecologyroutesformicrobialgrowthhaveemerged.Inordertominimize
thelossofqualityandtocontrolmicrobialgrowth,andthusensureproductsafetyand
convenience,ahurdleapproachappearstobethebestmethod(Alzamoraetal..2000).
AccordingtoAlzamoraetal.(2000).hurdletechnologycanbeappliedseveralwaysinthe
designofpreservationsystemsforminimallyprocessedfoodsatvariousstagesofthefood
chain:
•Asa'‘backup”measureforexistingminimallyprocessedproductswithshortshelflife,
todiminishmicrobialpathogenicriskand/orincreaseshelflife(i.e.,useofnatural
antimicrobialsorotherstressfactors,inadditiontorefrigeration).
•Asanimportanttoolforimprovingthequalityoflongshelflifeproductswithout
diminishingtheirmicrobialstability/safety(i.e..useofheatcoadjuvantstoreducethe
severityofthermaltreatments).
•Asasynergist.AccordingtoLeistner(1994).infoodpreservedbyhurdletechnology,
thepossibilityexiststhatdifferenthurdlesinafoodwillnotjusthaveanadditiveeffect
onstability,butcouldactsynergistieally.Asynergisteffectcouldworkifthehurdlein
afoodhitsdifferenttargets(e.g..cellmembrane.DNA.enzymesystems.pH.aw.Eh)
withinthemicrobialcell,andthusdisturbsthehomeostasisofthemicroorganisms
presentinseveralaspects.Therefore,employingdifferenthurdlesinthepreservationof
aparticularfoodshouldbeanadvantage,becausemicrobialstabilitycouldbeachieved
withacombinationofgentlehurdles.Inpracticalterms,thiscouldmeanthatitismore
effectivetousedifferentpreservativesinsmallamountsinafoodthanonlyone
preservativeinlargeamounts,becausedifferentpreservativesmighthitdifferent
targetswithinthebacterialcell,andthusactsynergistieally(Leistner.1994).
Duringthelastdecade,minimallyprocessedhighmoisturefruitproducts(HMFP),whichare
ambientstable(withaw>0.93).havebeendevelopedinsevenLatinAmericancountries,
undertheleadershipofArgentina.Mexico,andVenezuela.Thisnoveltechnologywas
successfullyappliedtopeachhalves,pineappleslices,mangoslicesandpuree,papayaslices,
chicozapoteslices,bananapuree,plum,passionfruit,tamarind,wholefigs,strawberries,and
pomalaca(Alzamoraetal..1995).Themethodologyemployedwasbasedoncombinationsof
mildheattreatments,suchasblanchingfor1-3minuteswithsaturatedsteam,slightlyreducing
theayy(0.98-0.93)byadditionofglucoseorsucrose,loweringthepH(4.1-3.0)byadditionof
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DuringstorageofHMFP,thesorbateandsulphitelevelsdecreased,aswellasawlevels,due
tohydrolysisofglucose(Alzamoraetal..1995).
Theworkpresentedinthismanualdemonstratesatwhichstageofmaturityafruitorvegetable
shouldbeharvested,andpackaged,foroptimumstorability.marketablelife,quality,andall
aspectsrelatedtofinaluseoffreshandprocessedproducts.Someusefulexamples,figures,
andtablesconcerningthepreservationoffruitsandvegetablesbycombinedmethodsare
demonstrated
Thisbookalsosummarizesthebasicprinciplesofharvestandpost-harvesthandlingand
storageoffreshfruitsandvegetables.
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