现代食品工程学现代食品工程学AdvancedFoodEngineering/EngineeringPropertiesofFoodsTel:Fax:E-mail:LectureforpostgraduateLectureforpostgraduatestudentAutumnof2010studentAutumnof20101食品工程学品质变化速度科学回答：是什么？为什么？技术回答：做什么？怎么做？科学是发现，技术是发明。科学是创造知识的研究技术是综合利用知识于需要的研究工程：依靠、使用复杂的系统、工具、设备或装备来完成的工作。2食品工程学品质变化速度 食品加工中的品质变化速度食品加工中的品质变化速度VelocityofQualityChangeduringFoodProcessingVelocityofQualityChangeduringFoodProcessingVelocityofQualityChangeduringFoodProcessingVelocityofQualityChangeduringFoodProcessing3食品工程学品质变化速度 食品原料：食品原料：食品原料：食品原料：多组分，不均质，多样性生物材料；品质变化：品质变化：品质变化：品质变化：物理的，化学的，生化的及其综合变化； 食品反应工学食品反应工学食品反应工学食品反应工学-品质变化速度论 4食品工程学品质变化速度食品加工操作（处理）：食品加工操作（处理）：物理性物理性物理性物理性-机械的，扩散的，热的操作。机械的，扩散的，热的操作。 如洗净，如洗净，浸渍，发泡，混和，过滤，抽提，结晶，冷冻，浓缩，浸渍，发泡，混和，过滤，抽提，结晶，冷冻，浓缩，干燥等。干燥等。化学性化学性化学性化学性-反应的操作。如化学反应，酶反应，微反应的操作。如化学反应，酶反应，微生物发酵，杀菌，烹饪等。生物发酵，杀菌，烹饪等。5食品工程学品质变化速度 内容内容: :品质变化速度式设定;感官性状的变化（味道、气味、色泽、质地）；营养成分的变化（碳水化合物、蛋白质、脂质、维生素等）；氧化（酶促和非酶促；油脂氧化、维生素氧化、血红蛋白氧化等）；着色（酶促着色、非酶促着色）；漂洗；糊化（糊化与老化）；蛋白质变性（加热、冻结、其他）；其他品质变化（盐渍、糖渍、醋渍、薰蒸等）6食品工程学品质变化速度 QualityincludessafetyqualityandsensorialqualityQualityincludessafetyqualityandsensorialqualityQualityincludessafetyqualityandsensorialqualityQualityincludessafetyqualityandsensorialqualityFoodsafety:thatisthefreedomfromharmfulFoodsafety:thatisthefreedomfromharmfulchemicalormicrobialcontaminationsatthechemicalormicrobialcontaminationsattheproduction,processing,distributionandconsumption.production,processing,distributionandconsumption.Majorsensorialqualityattributesoffoodsaretexture,Majorsensorialqualityattributesoffoodsaretexture,color,flavor,appearanceandnutritivevalue,somecolor,flavor,appearanceandnutritivevalue,someundesirablechangesmayoccureitherpriortoorundesirablechangesmayoccureitherpriortoorduringdistributionandduringdistributionandconsumption.consumption.7食品工程学品质变化速度 DeteriorativereactioninfoodsDeteriorativereactioninfoodsDeteriorativereactioninfoodsDeteriorativereactioninfoodsA.enzymaticchangesA.enzymaticchanges-enzymesarecomplex,globularproteinsthathave3importantcharacteristics:(1)Actascatalysts,acceleratetherateofchemicalreactionsbyfactorsof10121020overuncatalyzedreaction.(2)Highlyspecific,enablethefoodprocessorstoselectivelymodifyparticularfoodcomponents.(3)Havearegulatoryrole,controlthebiochemicalprocesses.Typesofenzymes:Exogenousadditionofenzyme(frommicroorganism)inthemilkduringmanufacturingcertaincheeses,intentionalfermentation(desirable),spoilage(undesirable).Endogenousinvolvingautolysisoffishpostharvest(off-flavor),thesenescenceandspoilageoffruitsandvegetablespostharvest,glycolysisinpostmortem,prerigormuscleandsuberization(woundhealing)ofplanttissuespostharvest,oxidationoflipidsbylipaseandlipoxygenase8食品工程学品质变化速度 B.ChemicalchangesB.Chemicalchangeschemicalreactionsleadtodeteriorationoffoodqualityorimpairmentofsafety-non-enzymaticbrowning(Maillardreaction=reducingsugar+aminoacid)-lipidhydrolysis/oxidation-proteindenaturation-proteincross-linking-proteinhydrolysis-oligo-andpolysaccharidehydrolysis-polysaccharidesynthesis-degradationofspecificnaturalpigment-glycolyticchanges9食品工程学品质变化速度 SensoryQualitySensoryQualitySensoryQualitySensoryQualitya.Lipidoxidation-developmentofoff-flavor.-reactwithproteinandresultinextensivecross-linking.b.Non-enzymaticbrowning、-oneofthemajordeteriorativechemicalreactionsoccursduringstorageofdriedandconcentratedfoods.-leadstoformationofinsolublebrownpolymers(mw1000).c.Colorchange-changeinstructureorcontentofchlorophyll,hempigment,anthocyanins,carotenoids.d.Flavorchanges-flavorhasevolvedtoausagethatimpliesandoverallintegratedperceptionofthecontributingsensesofsmellandtasteatthetimeoffoodconsumption.-thepermeabilityofpackagingmaterialsisofimportanceinretainingdesirablevolatilecomponentswithinpackage,orinpermittingundesirablecomponentstopermeatethroughpackagefromtheambientTo.NutritionalQualityNutritionalQualityNutritionalQualityNutritionalQualityfourmajorfactorswhichimpactonnutrientdegradationandcanbecontrolledtovaryingextentsbypackagingareLight,O2concentration,ToandAw10食品工程学品质变化速度 C.PhysicalchangesC.Physicalchangesphysicalpropertiesincludegeometrical(size,shape,volume,densityandsurfaceareaasrelatedtohomogeneousfoodunits,aswellasgeometricaltexturalcharacteristicssuchasreferringtoparticlesizeandshape;referringtoparticleshapeandorientation),thermal,optical,mechanical,rheological,electrical,andhydrodynamicproperties-forfoodscontainingsolidcarbohydrates,thelargesteffectinphysicalpropertiesresultsfromsorptionofwater,especiallyfortherecrystallizationofamorphouscarbohydrate,e.g.inboiledsweetsleadingtostickinessandgraining,inmilkpowdersleadingtocakingandlumpiness11食品工程学品质变化速度 D.BiologicalchangeD.Biologicalchangea. Microbiologicala. Microbiological-majorgroupsofmicroorganismsfoundinfoodsarebacteriaandfungi(yeastsandmolds)-foodsarefrequentlyclassifiedonthebasisoftheirstabilityasnon-perishable,semi-perishable,perishableFactorsaffectingmicrobialgrowth1.intrinsicparameters:Moisture,pH2.extrinsicparameters:Temperature(e.g.30 40oCreferredtomesophiles),RH%,gasesinenvironment.b. Macrobiologicalb. Macrobiological1.InsectPests1.InsectPests-fliesandcockroaches,moth,beetles2.Rodents2.Rodents-propersanitation(allpackagingmaterialapartfrommetalandglasscanbeattackedbyratsandmice)12食品工程学品质变化速度案例13食品工程学品质变化速度MethodsMethodsSurimiSurimiSurimiSurimiSurimipasteSurimipasteSurimipasteSurimipasteHeat-inducedgelHeat-inducedgelHeat-inducedgelHeat-inducedgel1.1.Defrosting(half-thawedDefrosting(half-thawed). ). ). ).2.GrindingwithNaCl,additives,chilleddistillwater,etc.2.GrindingwithNaCl,additives,chilleddistillwater,etc.3.Stuffingintoa35mmdiameterfoldedPVDCtube3.Stuffingintoa35mmdiameterfoldedPVDCtubecasing,ca.100geachsample.casing,ca.100geachsample.Incubatedatacertaintemperatureforadefinitetime,Incubatedatacertaintemperatureforadefinitetime,including:including:*One-stepheating(*One-stepheating(60Ckamabokogel) )*Two-stepheating(*Two-stepheating(cookingat85C/30minafterone-stepsetting) )Measureindices:Measureindices:breakingforce(g),breakingstrain(mm),breakingforce(g),breakingstrain(mm),whiteness,foldingtest,compositionanalysis,andSDS-PAGE,whiteness,foldingtest,compositionanalysis,andSDS-PAGE,etc.etc.14食品工程学品质变化速度GelationcurveofwalleyepollacksurimibyGelationcurveofwalleyepollacksurimibyheatingtemperatureandheatingtimeheatingtemperatureandheatingtimeHeatingHeatingtemperaturetemperature15食品工程学品质变化速度Three-dimensionalconfigurationofbreakingThree-dimensionalconfigurationofbreakingforceofwalleyepollacksurimigelsforceofwalleyepollacksurimigels SteepmountainandVvalleytypesurimiSteepmountainandVvalleytypesurimiSteepmountainandVvalleytypesurimiSteepmountainandVvalleytypesurimiEasysetandeasycollapsesurimiEasysetandeasycollapsesurimiEasysetandeasycollapsesurimiEasysetandeasycollapsesurimi16食品工程学品质变化速度V-valleytypesurimiV-valleytypesurimiSilvercarpBig-headcarpChinesesnake-headBluntsnoutSilvercarpBig-headcarpChinesesnake-headBluntsnoutbreambream PlateautypesurimiPlateautypesurimiTilapiaGrasscarpMudcarpCommoncarpTilapiaGrasscarpMudcarpCommoncarp17食品工程学品质变化速度Calculationofgelationrate:Calculationofgelationrate:Calculationofgelationrate:Calculationofgelationrate:WhereTWhereT1/21/2isthetime(sec.)requiredforreachingthehalf-maximalbreakingisthetime(sec.)requiredforreachingthehalf-maximalbreakingforce.force.K=1/(TK=1/(T1/21/2),s),s-1-1K KD D=(lnG=(lnG0 0-lnG-lnGt t) ) 1/t,s1/t,s-1-1WheretheGWheretheG00andGandGt twerethebreakingforcebeforeandafterheatingfortwerethebreakingforcebeforeandafterheatingfortsecond.second.Calculationofgeldisintegrationrate:Calculationofgeldisintegrationrate:Calculationofgeldisintegrationrate:Calculationofgeldisintegrationrate:T1/2(1500sec)(1500sec)160160g(0.5Fmax)g(0.5Fmax)A AB BC C18食品工程学品质变化速度Arrheniusequation:Arrheniusequation:Arrheniusequation:Arrheniusequation:K=KK=K0 0exp(-Ea/RT)exp(-Ea/RT)857060504030(C)*Heat-inducedgelationofsurimioccursduetodifferentmechanismHeat-inducedgelationofsurimioccursduetodifferentmechanismattheupperandlowertemperaturesidesofaboundaryofaround50attheupperandlowertemperaturesidesofaboundaryofaround50C.C.19食品工程学品质变化速度DisintegrationrateconstantsofdifferentsurimigelsDisintegrationrateconstantsofdifferentsurimigels20食品工程学品质变化速度Thank you for your attention WANGXI-CHANGWANGXI-CHANGWANGXI-CHANGWANGXI-CHANGSHOU,ChinaSHOU,ChinaSHOU,ChinaSHOU,China21食品工程学品质变化速度