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Protein Functionality in Food Systems

By Marjorie Rose,2014-02-18 12:47
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Protein Functionality in Food Systemsin,In,Food,food

    Protein Functionality in Food Systems

    CHINA

    

    M

    

    EA

    

    TRESEA

    

    RCC

    

    ENTERH

    WWW.cmrc.com.cn

    肉类研究

    MEATRESEARCH

    2010.2

    ProteinFunctionalityinFoodSystems

    WANGPanpan

    (CollegeofFoodScience,SouthwestUniversity,Chongqing400715,China) Abstract:Thestructure,shape,color,smellandtasteoffoodweredecidedbyproteinfunctionality.

    Theutilizationofproteinwillimprovebychangingtheproteinfunctionality.Proteinfunctionalityisalso

    advantagetomaintainandutilizethenutritionoffood.Thispapersummarizedthenature,classification,

    factorsandprospectofproteinfunctionality.Itccnprovideatheoreticalbasisforapplicationo

fproteinin

    foodindustry.

    Keywords:protein;functionality;factors

    Themainarguments

    Fisthedefinitionofpro.tefi:

    propertiesandchemicalpropertiesduringtheprocessing, storage,preparationandsalephaseinfoodindustry. Secondoneisthemaininfluencingfactorsofprotein functionality.Theyincludetheprotein'ssize,protein's shape,compositionandsequenceofaminoacid,charge distribution,proteinstructure,ratioofhydrophobicity andhydrophilicityandsoon.

    Lastoneisclassificationofproteinfunctionality.It includeshydrationproperty,surfaceproperty,sensory propertyandinteractionofproteinmolecules. 1ntroduction

    Proteinisanimportantcomponentoffood.Itnotonly canimprovefood'nutritionalvalueandprovideessential aminoacidforthebodybutalsoplayanimportantrole instructure,shape,color,fragranceandtasteoffood. Allthesearemainlydependedonthedifferentprotein functionality.

    Theapplicationsofproteinsaremainlydecidedby proteinfunctionality.Alongwithgrowthofindustrial standardsandadditionoffoodspeciesthefoodqualitytoa greatextentdependedonthecompositions'characteristic. Comparedwithotherfoodingredientsthefunctionof proteincannotbereplaced.Proteinfunctionalityplayed animportantroleonorganolepticquality.Italsoplayeda mainroleonphysicalpropertiesoffoodcomponentduring

Eeceived:14August2009

    theprocedureofpreparingandprocessing.

    Therefore,itisnecessarytounderstandingthe functionalityofprotein.It'snotonlyadvantagetouse theseproteinscorrectlybutalsoisbenefitforusingand maintainingnutrients.Simultaneouslyitcouldprovidea theoreticalbasisforapplicationofproteininfoodindustry. 1Thedefinition,classificationandinfluencing factorsofproteinfunctionality

    1.1Thedefinitionofproteinfunctionality

    Itreferstoprotein'sphysicalandchemicalproperties duringthestorage,preparationandsalestageinfood industry.Theproteinfunctionalitysuchasgelation, solubility,emulsification,viscosityplaysanimportant roleinfoodprocessing.Proteinisanimportantingredient inthefoodprocessing.Theinfluenceofprotein functionalityisutmostlytofoodquality.Therefore, itisnecessarytounderstandthefunctionalpropertiesof protein.

    1.2The~afttmdngfactorsofproteinfunctionality Themaininfluencingfactorsofproteinfunctionality includeprotein'ssize,protein'sshape,compositionand sequenceofaminoacid,chargedistribution,protein structure,ratioofhydrophobicityandhydrophilicity, flexibility,rigidity,theinteractionofproteinmolecules andsoon.Externa1influencessuchastemperature,pH value,saltconcentrationandpressure,etcalsoplayeda mainrole.Inaddition,proteinfunctionalitiesarealso affectedbyinteractionbetweenproteinmoleculesand

20}o毒幕:期总肇732期互

    otherfoodcomponent,storageconditionsandsoon. 1.3Theclassificationofproteinfunctionality Accordingtothefunctionalityitcanbedividedintothe followingseveralkinds.

    1.3.1Hydrationproperty

    Hydrationpropertydependsontheinteractionbetween proteinandwater.Itincludeswaterabsorptionand retain,wettability,expandability,adhesiveness, dispersivity,solubility,viscosityandsoon. 1.3.2Interactionofproteinmolecules

    TheinteractionofProteinmoleculesinclude sedimentation,gelation,organization,theformationof doughandsoon.

    1.3.3Surfaceproperty

    Surfacepropertiesofproteininvolvedintheinteraction ofproteinindifferentpolarity.Itmainlyincludessurface tension,emulsifiability,filmforming,etc. 1.3.4Sensoryprope

    Sensorypropertiesofproteininfoodsysteminvolvdinthe turbidity,mastication,color,flavorandsoon. Thefunctionalitiesofproteinarenotindependent. Suchasviscosityandsolubilityincludetheinteractionof proteinmoleculesandhydrationproperty.Thegelation alsoincludestheinteractionofproteinmoleculesand hydrationproperty.

    2Thefunctionalityofprotein

    2.1Hydrationproperty

    Hydrationpropertyreferstotheinteractionbetween peptidesandsidechainaminoacidsofproteinsandwater

    molecular.Macroscopicaspectthecombinationofprotein andwaterisagradualprocess.Combinedmoistureformed first.Thenmultimolecularwaterformed.Ifconditions permittedproteinshydratedfuthermore.Theperformance isthatproteinsgrowedfullybyswellinginteraction.Then swellinginteractionconfinedtoformcolloid. Alotoffoodsarehydratedsolidsystem.The

    chemicalproperties,physicalpropertiesandrheological propertiesoffoodcomponentsarenotonlyaffectedby waterbutalsobywateractivity.

    Therheologicalpropertyandtextureoffood

    dependedoninteractionbetweenwaterandotherfood components.It'sespeciallyaffectedbytheinteraction ofmacromoleculesuchasproteinsandpolysaccharides. Therearealotoffunctionalitiessuchasdispersivity, wettability,solubility,waterretentioncapability, gelation,thickening,viscosity,condensation, emulsificationandsoondecidedbytheinteraction betweenwaterandprotein.Hydrationpropertyalsoplayed animportantroleonmeatandthetextureofthedough. Theotherfunctionalitiesofproteinarealsodecidedby

    hydrationproperty.

    2.1.1Solubility

    Thesolubilityofproteinrefersthatthelnteractions betweenprotein-proteinandprotein--solventgetto

    thermodynamicsbalance.Asmacromolecularorganic compoundtheformofproteinsarecolloidaldispersionin thewaterrathersolutioninchemicalsense.Therefore. proteinwhichinthewatercalledsolutionisonlyahabit.

    Thesolubilityofproteincanberepresentedbyusing nitrogensolubilityindex,watersolubleprotein,water

    dispersibleprotein,andproteindispersancyindex.PDI andNSIhasbeenadoptedasthesolubilityofproteinby theassociationofAmericanoilchemist.

    Theproteinfunctionalityincludesthickening, foaming,emulsificationandgelatinizationwereaffected bysolubilityofproteinsinagreatdegree.Abigsolubility ofproteinsnotonlycanmakethemspreadrapidlyin thesystembutalsoareadvantagetomakethemspread tointerfaceofairorwater.Itcanalsoimproveother functionalitiesofprotein.

    Proteinsolubilityisveryimportantinpractical application.Itisusefulforextractingandseparatingof naturalprotein.Therefore,itcouldbeusedtomeasure degenerationofprotein.It'sanindextojudgmentthe potentialvalueofprotein.Inadditiontotheapplication ofproteininbeveragearealsodirectlyrelatedtoprotein solubility.

    Proteinsolubilityimprovedalongwithtemperature increasedintheconstantpHvalueandionintensity.Some hydrophobicityproteinsuchasbetacaseinandsome cerealproteinnegativelycorrelatedwithtemperature. Thesolubilityofproteindroppedwhentemperatureis over40?.Proteinstructure'sdenaturationduetothermal effectandallthiswillpromotetheroleofaggregationand precipitation.Dielectricconstantofwaterwil1declineand electrostaticinteractionofproteinmoleculeswillincrease byjoiningwithorganicmolecular.

    Thedielectricconstantofwatermolecularwill

    bereducedandelectrostaticforceofproteinbetween moleculesandintermolecularwillbeincreasedbyadding organicsolvents.Theformationofhydrogenbondsand electrostaticforcewhichwerepromotedbydielectric constant'reductionwil1reducesolubilityofproteinsin organicsolvent-water.

    2.1.2Viscosity

    Theresistancecaseoffluidwasreflectedbysolution viscosity.Dispersedcomponentsoffoodswereinfluenced byviscosityanditcanalsoprovidegoodtasteandimprove tasteindirectly.Forexample,crystallizationofsome foodcompositioncanbecontrolledbysolutionviscosity. Thegrowthofcrystallizationcanalsobeconstrainted 2070耳第:期总第7;2

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    bysolutionviscosity.Viscositywasinfluencedbymany factorsincommonprocessingsuchashightemperature

    shorttimesterilizing,proteoclasticaction,inorganic ion,etc.

    Themainfunctionsoffluidfoodsuchasbeverage, broth,sauce,creamandsoonareviscosityand consistency.Foods'qualityandtextureareimprovedby solutionviscosity.Inconveying,heating,coolingand dryingoffoodprocessingviscosityalsopalysanimportant role.

    Thereiscorrelationbetweenviscosityandsolubility. Theviscosityofinsolubleproteininwaterisnothigh. Theviscosityofsolubleproteinwhichhaspoorwater absorptivityandsmallswellabilityislowinneutral orisoelectricpoint.Solubleproteinwithhighwater

absorptivitywillhaveahighviscosity.

    Themaininfluencefactorsofprotein'sviscosity areproteinmoleculesandapparentdiameter.Thegreater apparentdiameterhasahigherviscosity.

    Apparentdiameterdependsonthefollowing

    parameters.

    Firstoneistheinherentcharacteristicsofprotein moleculessuchasmolarmass,size,volume,

    structure,charge,etc.

    Secondoneistheinteractionbetweenproteinand solvent.Theswellability,hydrationandsolubilitywillbe influencedbythisinteraction.

    Lastoneistheinteractionbetweenandprotein. Thisinteractiondependsonthesizeoftheaggregate.the interactionbetweenproteinandproteinisthemainfactor forhighconcentrationoftheproteinsystem. 2.1.3Thedeterminationofhydrationproperties Hydrationpropertiesareusuallymeasuredbywater preservingcapabilityinactualproduction.Water preservingcapabilityreferstotheabilityofwateris absorbedorretainedintheorganizationbyproteins. Reservedwaterincludeshydratewater,fluiddynamics waterandphysicaltrappedwater.Thewaterpreserving capabilityplsysanimportantroleontender,juicy sexual,softness,textureandsoon.

    Therefore,food'squalityismainlydecidedbywater preservingcapability.

    Therearefourmethodsformeasuringhydration propertiesofprotein.

    Firstoneisrelativehumiditymethod.Thismethod

    usedtomeasureabsorbedorlostwaterwhenthewater activityatacertainvalue.Itcouldbeusedtoevaluate hydroscopicityandcakingphenomenon.

    Secondoneisswellingmethod.Proteinpowderis placedintheglassfilterofcapillarytubewithscalein thebottom.Proteinpowdercouldabsorbthewaterfrom capillarytubespontaneously.Thismethodcouldmeasure therateanddegreeofhydration.

    Thirdoneiswatersaturationmethod.Itistomeasure thehumidityofproteinsolutionneededforgetting saturatedstate.

    Lastoneisexcessivewatermethod.Itmakesprotein samplescombinewithexcessivewaterthatmorethan proteincouldbecombinedwith.Itmakestheexcess waterbeseparatedbyfilteringorlowspeedcentrifugation

    separation.Thismethodissuitableforlowsolubility ofprotein.Butitmustbecorrectedforsolubleprotein samples.

    Watersaturationmethod,excessivewatermethod andswellingmethodcouldbeusedtomeasurehydrate water,nonfrozenwaterandcapillarywaterwhichis keptbyphysicalfunctionofproteinmolecules. 2.2Surfaceproperty

    Proteinisamphiphaticmoleculewhichcouldbetransfered togaswaterinterfaceorwater-oilinterfacespontaneously. Alloftheproteinsareamphiphaticmolecule.Butthere aresignificantdifferencesonprotein'ssurfaceproperty. Becausethesurfacepropertiesofproteinsareextremely complex.Theunderstandingaboutitisnotverycomplete. Nowmakeabriefintroductionofemulsifiabilityand

foamingproperty.

    2.2.1Emulsifiabilityofprotein

    Emulsifiabilityreferstotwoormoreinsolubleliquidsuch aswaterandoiltoformationemulsionbymechanical agitationoraddingemulsifyingagent.Proteinisanatural amphiphaticmoleculewhichchouldbeactedbywateras wellasbylipid.

    Somenaturalfoodssuchasmilk,vitellus,coconut milk,butter,cream,saladsauce,frozendessert, sausage,cakesandsoonareallemulsifiedproducts. Inthesefoodsproteinplaystheroleofemulsification. It'smainlyduetoproteinscanbetransferedtooil- waterinterfaceorgas-waterinterfacespontaneously. Hydrophobicgroupstransfertooilorgasphaseinterface

    andhydrophilicgroupstransfertowaterinterface.Protein adsorptionlayerwhichplaysaemulsificationrolewillbe formed.

    2.2.2Thedeterminationofemulsifiability

    Thecommonmethodsformeasuringemulsifiabilityare emulsioncapacity,emulsionstability,emulsification activityindex,etc.

    2.2.2.1Emulsioncapacity

    Emulsioncapacityisalsocalledemulsionability.Itrefers toemulsifyingoil'svolumepergramofproteincould emulsifyingbeforeemulsifyingliquid'sphasetransition. Acertainamountofproteinsolutionisaddedoilor 20fo牟甍:期总鐾1;2

    meltedfatbystirringwiththesamespeed.Measureoil volumebeforephasetransitionwiththephenomenonthe colorchanged,viscositychangedorresistanceadded.

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