食品添加剂AntioxidantsPPT资料.ppt
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食品添加剂AntioxidantsPPT资料.ppt
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ANTIOXIDANTAntioxidantsThechemicalcompoundswhichcandelaythestartorslowtherateoflipidoxidationreactioninfoodsystems.GeneralMechanismsofAutooxidation14131211109-HCH2CHCHCH2CHCHCH2R(CH2)3CH3INITIATION(METAL)1211109+O2(CH2)4CH3CHCHCHCHCH2RCH1211109+H(CH2)4CH3CHCHCHCHCH2RCHOOPROPAGATION121110HYDROPEROXIDEDECOMPOSION-OHCHCHCHCHCHCH2R(CH2)4CH3OOH1211109(CH2)4CH3CHCHCHCHCH2RCHO+HTERMINATION(PENTANE)CH3(CH2)3CH2CH3(CH2)3CH3OCHCHCHCHCHCH2R+1211109MinimizationofLipidOxidationIfacompoundinhibitstheformationoffreealkylradicalsintheinitiationstep,orifthechemicalcompoundinterruptsthepropagationofthefreeradicalchain,thecompoundcandelaythestartorslowthechemicalreactionrateoflipidoxidation.Theinitiationoffreeradicalformationcanbedelayedbytheuseofmetalchelatingagents,singletoxygeninhibitors,andperoxidestabilizers.Thepropagationoffreeradicalchainreactioncanbeminimizedbythedonationofhydrogenfromtheantioxidantsandthemetalchelatingagents.CharacteristicsofAntioxidantsThemajorantioxidantscurrentlyusedinfoodsaremonohydroxyorpolyhydroxyphenolcompoundswithvariousringsubstitutions.Thesecompoundshavelowactivationenergytodonatehydrogen.Theresultingantioxidantfreeradicaldoesnotinitiateanotherfreeradicalduetothestabilizationofdelocalizationofradicalelectron.Theresultingantioxidantfreeradicalisnotsubjecttorapidoxidationduetoitsstability.TheantioxidantfreeradicalscanalsoreactwithlipidfreeradicalstoformstablecomplexcompoundsAntioxidantsOHC(CH3)3OCH3C(CH3)3(CH3)3CCH3OHButylatedHydroxyTolueneButylatedHydroxyAnisoleOHOHOHCOOC3H7PropylGallateOHC(CH3)3OHTBHQCHCHOOHOHOHCH3CH3OHCHOOHCHOHCH3CH3CH3CH3GossypolAntioxidantsMechanismofAntioxidantsHydrogendonationtofreeradicalsbyantioxidants.Formationofacomplexbetweenthelipidradicalandtheantioxidantradical(freeradicalacceptor).ReactionofantioxidantswithradicalsR+AHRH+ARO+AHROH+AROO+AHROOH+AR+ARARO+AROAROO+AROOAAntioxidant+O2OxidizedAntioxidantStableResonanceFormationofBHAOHC(CH3)3OCH3R,RO,orROOC(CH3)3OCH3OOCH3C(CH3)3O.C(CH3)3OCH3OOCH3C(CH3)3ORH,ROH+orROOH.OCH3H2OHCH3CH3H2(CH2)3CH(CH2)3CH(CH2)3CH(CH3)2CH3CH3a-tocopherolO2CH3CH3CH3OCH2OCH2C(CH2)3CH(CH2)3CH(CH3)2CH3CH3CH3OHa-tocoquinoneTocopherolandOxygenReactionMechanismsofMetalsinAcceleratingLipidOxidationHydroperoxidedecompositiontoformperoxyoralkoxyradical.Fe3+ROOHFe2+ROO+H+Fe2+ROOHFe3+RO+OH-Formationsofalkylfreeradicalbydirectreactionwithfatsandoils.Fe3+RHFe2+R+H+Activationofmolecularoxygenforsingletoxygenformation.Fe2+O2Fe3+O-21O2KindsofMetalChelatorsMetalchelatorsdeactivatetracemetalsthatarefreeorsaltsoffattyacidsbytheformationofcomplexionorcoordinationcompounds.1.Phosphoricacid2.Citricacid3.Ascorbicacid4.Ethylene-Diamine-Tetra-Acetate(EDTA)OMCOCH2OCOCH2NCH2CH2OONCOCH2COCH2MetalIonsEDTAComplexFormationSynergisminLipidOxidationSynergismoccurswhenmixturesofantioxidantsproduceamorepronouncedactivitythanthesumoftheactivitiesoftheindividualantioxidantswhenusedseparately.Tohavemaximumefficiency,primaryantioxidantsareoftenusedincombinationwith
(1)otherphenolicantioxidants,orwith
(2)variousmetalchelatingagents.FactorsAffectingtheEfficiencyofAntioxidant1.Activationenergyofantioxidantstodonatehydrogenshouldbelow2.Oxidationpotentialshouldbehigh3.Reductionpotentialshouldbelow4.StabilitytopHandprocessing.5.Solubilityinoilshouldbe.AntioxidantSafetyFoodAdditive,MeatInspection,andPoultryInspectionActs.Totalconcentrationofauthorizedantioxidantsaddedsinglyorincombination,mustnotexceed200partspermillionbyweightonthebasisoffatcontentofthefood.PossibleFutureAntioxidants1.Polymericantioxidant.2.Antioxidantattachedtothepackagingmaterials.3.Developmentofnew,non-absorbablepolymericantioxidantsforuseinfoods.Long-TermSafetyofMonomericAntioxidantsPathologicaleffect.CarcinogenicpotentialInteractionswithenzymesEffectsofreproductionTheexactnatureofthemetabolismrateinman.IsolationandIdentificationofOxidationProductof2,6-Di-(Tert-Butyl)-4-MethylphenolHOCH2CH2OH3,3,5,5-Tetra-Bis-(Tert-Butyl)-4,4-Dihydoxyl-1,2-DiphenylethaneCHCH3,3,5,5-Tetra-Bis-(Tert-Butyl)-StillbenequinoneOOIdealAntioxidantsNoharmfulphysiologicaleffectsNotcontributeanobjectionableflavor,odor,orcolortothefatEffectiveinlowconcentrationFat-solubleCarry-througheffectNodestructionduringprocessingReadily-availableEconomicalNotabsorbablebythebodyBiochemicalControlofLipidOxidationBiochemicalControlofLipidOxidationinMayonnaiseCompositionofMayonnaiseComposition(%)Soybeanoil77.0Wholeegg7.0Water7.0Vinegar3.0Eggyolk2.0Glucose1.0Fructose1.0Salt0.9NaturalFlavor0.1100%Glucoseoxidase/catalaseReacti
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