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1、J.Agrlc.FoodChem.1991,39,1693-16951883EffectofLipidOxidationProductsontheTransesterificationActivityofanImmobilizedLipaseYiqunWangtandMichaelH.Gordon'DepartmentofFoodScienceandTechnology,UniversityofReading,WhiteknightsP.O.Box226,ReadingRG62AP,EnglandTheeffectofvaryingamountsoflinoleicacidhydr
2、operoxidesontheactivityofanimmobilizedlipase,Lipozyme,usedforthetransesterificationoffatshasbeenstudied.Theinitialactivityoftheenzymeisnotsignificantlyreducedevenbyaperoxidevalueof50mequivlkg,buttheoperationalstabilityisreducediftheperoxidevalueoftheoilisabove5mequivlkg,withtherateofenzymeinac
3、tivationincreasingwithperoxidevalue.Asamplewithinitialperoxidevalueof50mequivlkgcauseda50%lossofactivityaftereightbatchtreatmentsof10hpertreatment.Thelossofactivityisduetogenerationoffreeradicalsintheenzymefollowinghydroperoxidedecomposition.INTRODUCTIONperoxidedecomposition.Itwastheaimofthepr
4、esentstudytoinvestigatequantitativelytheeffectoflinoleicCatalytictransesterificationiscommonlyusedintheacidhydroperoxidesontheactivityofLipozymeduringoilsandfatsindustrytomodifythepropertiesofediblethetransesterificationofoils.fats.Chemicalcatalystssuchassodiumalkoxideorsodiummetalareusedonani
5、ndustrialscaletopromotemigrationMATERIALSANDMETHODSoffattyacylgroupsamongtriglyceridemoleculestoformaproductinwhichthefattyacylgroupsarerandomlyLipozymeIM20wasdonatedbyNovoNordiskBioindustriesU.K.Ltd.LipozymeIM20isapreparationofaMucormieheidistributed.Inrecentyearstherehasbeenconsiderablelipas
6、eimmobilizedonamacroporousanion-exchangeresinresearchoncatalysisbylipases(triacylglycerolacylhy-(Eigtved,1985).Theenzymeactivitywas28BIU/g,andthedrolase,EC3.1.1.3)thatarecapableofselectivetrans-moisturecontentwas12%(m/m).Soybeanlipoxygenase(Sigmaesterificationofoilsandfats.Inparticular,lipases
7、thattypeI,126500units/mgofsolid),triolein(95%),lauricacidselectivelycatalyzethetransesterificationofacylgroups(99%),andlinoleicacid(99%)werepurchasedfromSigmaatthe1,3-positionshavepotentialfortheeconomicChemicalCo.synthesisofcocoabutter
