食品專業(yè)英語-第二章 LESSON 2　FOOD RAW MATERIAL INGREDIENTS AND NUTRITION

食品專業(yè)英語FoodProfessionalEnglish01OVERVIEWOFFOODSAFETY02FOODRAWMATERIALINGREDIENTANDNUTRITION03ISSUESINFOODSAFETY04FOODADDITIVES目錄CONTENTS06FOODSAFETYTRACING07FOODSAFETYANDMICROBIALINFLUENCEFACTORS08FOODQUALITYMANAGEMENT09FOODQUALITYCONTROLANDSAFETYEVALUATION05FOODRISKANALYSISANDFOODQUALITY10CRISISMANAGEMENTFORFOODINDUSTRYLESSON2FOODRAWMATERIALINGREDIENTANDNUTRITIONIngredientsinfoodscanbedividedintotwomaincategories,namely,activeandinactive.Activeingredientscanbeconsideredasthosethatsupplyenergytothebodyorserveasitsnutrientsfoodsandsomefoodadditives.Inactiveingredientsdonotexertphysiologicalactionswheningestedorappliedtothebody.Theirprimaryfunctionistoactasdiluentsortofacilitatetheultimateintakeorutilizationoftheactiveingredients,suchasdietaryfiber.Thischapterisanintroductionoffoodrawmaterialwithemphasisonfoodrawmaterialingredientandnutrition.1.Meat1.1Meatandmeatproducts

Meatisanincreasinglyimportantsourceofhigh-valueanimalproteinworldwide.Meatandmeatproducts,referredtohereasredmeatsorpostmortemmusclesfrommammalianspecies(beef,veal,pork,andlamb/mutton),areanimportantcomponentindiet.Meatandmeatproductsareconsiderablesourcesofcholesterolinthediet.Therefore,inmostdevelopedcountries,ahighmeatintakecontributestoahigherthanrecommendedtotalfatsandsaturatedfatacids(SFA)intake.

Therefore,meatandmeatproductsarefrequentlycriticizedbynutritionistsandnationalhealthauthorities,whoadviceconsumerstopreferleanmeatsandlow-fatmeatproducts.1.2MeatandnutritionSkeletalmuscleofmeatconsistsofseveraltissues,suchasmusclefibersandconnectiveandadiposetissues.Musclefibers,intramuscularconnectivetissue,andintramuscularfatplaykeyrolesinthedeterminationofmeatandfishfleshquality.Generallyspeaking,skeletalmuscleconsistsofapproximately90%musclefibersand10%ofconnectiveandfattissues.Asaresult,ameatthatisrichinproteinswithahighproportionofessentialaminoacidsandpolyunsaturatedfattyacidsisconsideredtoexhibitgoodnutritionalquality.Meatfatcomprisesmostlymonounsaturatedandsaturatedfattyacids,witholeic(C18:1),palmitic(C16:0),andstearicacid(C18:0)beingthemostubiquitous.Nutritionalvalueisaffectedbythebalancebetweensaturatedfattyacids(SFA)andpolyunsaturatedfattyacids(PUFA).Inallspecies,thebulkofPUFAaredepositedinphospholipid(PL)inmuscle.Meatisalsoasignificantsourceoflong-chainn-3fattyacids,theintakesofwhicharewidelyjudgedtobetoolowatpresent.However,highlevelsofPUFAinmeatcanleadtolipidoxidationpostmortemwhichmaynegativelyaffecttheflavorofcookedmeatandthecolorofdisplayedmeat.Despitethesurgeinpoultryproductconsumptioninthepasttwodecades,redmeatsremaintohaveadominantmarketshareinallmusclefoodsproducedintheworld.Manycuredmeatproductsareavailableinthecurrentfoodmarket,forexample,traditionalporkproducts(hamandbacon),beefproducts(cornedbeef).2.SeafoodsTheincreasingdemandforseafoodmaybeduetoitshealthbenefits,especially,fishandshellfish.Recentyears,variousfishandshellfishsourcematerialssuchasskin,muscle,frame,bone,andinternalorgansarepresentlyutilizedtoisolateanumberofbioactivematerials.Skinandproteinremainingonfishframecouldbeusedascheapmaterialsforidentificationandisolationofbioactivepeptides.Fishboneisagoodsourceofcalcium.2.1FishandnutritionCollagenandgelatinarethemajorstructuralproteinfoundintheskinandbonesoffish.Collageniscommonusedinmedicalandpharmaceuticalindustriesespeciallyasdrugcarriers,basedonstructuralrolesandbettercompatibilitywithinhumanbody.Gelatinisaheterogeneousmixtureofhighmolecular-weightwater-solubleproteinsandhasauniqueaminoacidarrangementinitssequenceandcontainsrelativelyhighamountsofglycine,alanine,andproline.Fishframesresultingfromfilletingoperationscontainconsiderableamountofmuscleprotein.Framesofsomefishspeciesasidealproteinsourcehavebeenutilizedtoobtainfunctionalhydrolysates.Generallyspeaking,approximately65-70%ofthefishboneiscomposedofinorganicsubstances.Almostalloftheseinorganicsubstancesarehydroxyapatitecomposedofcalcium,phosphorus,oxygen,andhydrogen.2.2ShellfishandnutritionShellfishprovidehigh-qualityproteinwithallthedietaryessentialaminoacidsformaintenanceandgrowthofthehumanbody.Shellfishalsoprovideamountoffatandsaturated,monounsaturated,polyunsaturatedfattoahealthfuldiet.Previousresearchsuggestedthatcalciumcompoundsobtainedfromoystershellandfishgelatin-derivedpeptidescombinationcouldbeusedasaneffectivedietarycalciumsource.3.EggEggsarenowconsideredasahighlynutritiousfoodwithuniquecomponentsbytheWorldHealthOrganization(WHO)tobethereferenceproteinworldwide,towhichallotherproteinsarecompared.Eggshavenumerousfunctionsinfoodproductionsandthesefunctionsmakethemthepreferredingredientinmanyfoodformulations.However,theegghasbeensubjectedtonegativepublicitygenerallyrelatedtothecholesterolcontentformanyyears.Theeggisconsideredasnature’smostperfectfoodcontainingexcellentsourceofproteinofhighbiologicalvalue,highratioofunsaturatedfattyacidstosaturatedfattyacids,andexcellentsourceofmineralsandallthevitamins.3.1ComponentsineggandnutritionalvalueAnaverageheneggweighsabout57g,whichincludestheweightoftheyolk,white,andshell.Eachcomponentdiffersincomposition,asshowninTable1.Table1Chemicalcompositionofthehen’seggbypercentage(%)Components%WaterProteinFatAshWholeegg10065.511.811.011.7Eggwhite5888.011.00.20.8Eggyolk3148.017.532.52.0Shell11--------Source:USDA3.2TheyolkandeggwhiteAneggyolkcomprisesapproximately30-33%ofthetotaleggweight.Eggyolkprovidesalloftheegg’scholesterol,almostallofthefatandcontainshalfoftheprotein,mostofthecalcium,phosphorus,iron,zinc,andvitaminsB6,B12,A,andfolicacid,andhalfoftheriboflavinandthiamine.Therefore,generally,theyolkhasahighernutrientdensitythanthewhite,containingallofthevitaminsknownexceptvitaminC.Theyolkcontainstriglycerides,phospholipids,andsterols.Theprimaryphospholipidisphosphatidylcholineorlecithin.Proteinintheyolkisprimarilyvitellinwhichispresentinalipoproteincomplexaslipovitellinandlipovitellinin.Eggwhitecontainsabouthalfoftheproteinandriboflavin.Thewhiteoftheeggrepresentsapproximately55-60%ofthetotaleggweight.3.3Aircell,membranes,andshellTheaircelldevelopsbyaseparationofthetwoshellmembranes,usuallyatthelargeendoftheegg,astheeggcontentsshrinkduringcooling.Thenextlayersoftheeggaretheinnerandoutershellmembranes.Theserelativelythinkeratin-likemembranesareoneoftheeggschiefdefensesagainstbacterialinvasion.Theshellcomprises9-12%ofthetotaleggweight.Itconsistslargelyofcalciumcarbonate(94%)withsomemagnesiumcarbonate(1%),calciumphosphate(1%),andorganicmatter,chieflyprotein(4%).4.MilkandmilkproductsMilkandmilkproductshavelongtraditionsinhumannutritioncontainingnumerousessentialnutrients.Buthumanbeingsconsumelargeamountsofmilkofafewspecies,suchascows,waterbuffaloes,goats,andsheep,especiallycows.Milkconsistsofwater,lipids,carbohydrates,proteins,salts,andalonglistofmiscellaneousconstituents.Milkcontainsthenutrientsneededforgrowthanddevelopmentoftheyouth,andisaresourceoflipids,proteins,aminoacids,vitamins,andminerals.Alsoitcontainsimmunoglobulins,hormones,growthfactors,cytokines,nucleotides,peptides,polyamines,enzymes,andotherbioactivepeptides.

4.1ProteinBovinemilkcontainsabout3.3gprotein/100g(Table2).Themilkproteinhasahighbiologicalvalue,andmilkisthereforeagoodsourceforessentialaminoacids.Inaddition,milkcontainsawiderangeofproteinswithbiologicalactivitiesrangingfromantimicrobialonestothosefacilitatingabsorptionofnutrients,aswellasactingasgrowthfactors,hormones,enzymes,andantibodies.Thenitrogeninmilkisdistributedamongcaseins,wheyproteins,andnon-proteinnitrogen.Milkproteincontenthasbeendeterminedbytheanalysisfornitrogen(N).Thishastheadvantagesthatnitrogenisamajorconstituent,comprisingaboutone-sixthofthemassoftheprotein.Nitrogencontentsoftheindividualmilkproteinsarenearlythesame.Multiplicationby6.25hasbeenusedcommonlytoconvertnitrogencontenttoproteinonthebasisof16%nitrogeninmilkproteins.Table2Basiccompositionofgoat,cow,andhumanmilks(meanvaluesper100g)ConstituentsGoatCowHumanFat(g)3.83.64.0Protein(g)3.53.31.2Lactose(g)4.14.66.9TotalSolids(g)12.212.312.3Calories(cal)706968Thecaseincontentofmilkrepresentsabout80%ofmilkproteinsandalmostallofthecaseinsareassociatedwithcalciumandphosphate.Therefore,caseinsbiologicalfunctionistocarrycalciumandphosphate.Theothermilkproteins,calledwheyproteins,areadiversegroup.Wheyproteinsaretheliquidremainingaftermilkhavebeencurdledtoproducecheese,areusedinmanyproductsforhumanconsumption.Themilkwheyproteinsareglobularproteinsthataremorewatersolublethancaseins,andtheprinciplefractionsarebeta-lactoglobin,alpha-lactalbumin,bovineserumalbuminandimmunoglobulins.Wheyproteinsareconsideredasrapiddigestedproteinthatgiveshighconcentrationsofaminoacidsinpostprandialplasma.

4.2LipidsInaverage,cowmilkcontainsabout3.6gtotallipid/100g,andthisdataofgoatmilkis3.8.Milkisintheformofastableemulsionoffatglobulesdispersedthroughoutanaqueousphasecontainingthenon-fatsolids.Smallerfatglobuleswouldbebetterfordigestionaction.Averagediametersoffatglobulesforgoat,cow,buffalo,andsheepmilkswerereportedtobe3.5,4.5,5.9,and3.3μm,respectively.Triacylglycerols,whichaccountforabout95%ofthelipidfraction,arecomposedoffattyacidsofdifferentlength(4-24C-atoms)andsaturation.Adietrichinmilkfatthereforemayhelptoincreasethisratiointhetotaldietaryfattyacids.Morethanhalfofthemilkfattyacidsaresaturated.Thesaturatedfattyacidslauricacid,myristicacid(14:0)andpalmiticacid(16:0)raisebloodcholesterollevels.Dietsrichinsaturatedfathavebeenregardedtocontributetodevelopmentofheartdisease,weightgainandobesityTheconcentrationofPUFAinmilkisabout2g/L,andthemainPUFAinmilkarelinoleicacid(18:2omega-6)andalpha-linolenicacid(18:3omega-3),whichmaybeconvertedtofattyacidswith20carbonatoms,suchasarachidonicacid(20:4omega-6)andeicosapentaenoicacid,(EPA)(20:5omega-3).4.3MineralsandvitaminsMilkcontainsmanyminerals,vitamins,andantioxidants.MostimportantantioxidantsinmilkarethemineralseleniumandthevitaminsE.Theantioxidantshavearoleinpreventionofoxidationofthemilk,andtheymayalsohaveprotectiveeffectsinthemilk-producingcell,andfortheudder.Milkanddairyproductsprovidemorethanhalfofthecalciuminthetypicaldiet,anddailyintakeofmilkanddairyproductsthushasacentralroleinsecuringcalciumintake.Thecalciumconcentrationinbovinemilkisabout1g/L.

Milkanddairyproductsarealsogoodsourcesofmagnesiumandzinc,containingabout100mgmagnesium/Land4mgzinc/Lmilk.MilkalsocontainsvitaminsA,riboflavin,andvitaminB12.5.AgriculturalproductsCerealfoodconsumptionhasrisensubstantiallyinpopularityandnutritionalorfunctionalcereal-basedfoodsarestartingtoplayanimportantroleinnewproductdevelopment.Indevelopingcountries,thepreventionofprotein-energyandmicronutrientdeficienciesshouldalsobeconcerned,butdevelopedcountriesshouldfocusondeterringthealarmingcasesofobesityandmetabolicsyndromethatleadtomanychronicdiseases,includingdiabetes,highcholesterol,andhypertension.Thestructureissimilarinallgrains.Eachkernelofgrainiscomposedofthreeparts,thegerm,endospermandbran,andifallarepresentinagrain,ita“wholegrain”,suchaswholewheat.Whenthebranorgermoftheseedareremovedorseparatedfromthekernelinmilling,aproductisnolonger“wholegrain,”butrather,“refinedgrain”.Themostwidelyusedarerice,wheatandmaize,whichprovidemorethan90%ofthetotalcerealcalories,mostoftheprotein,B-vitamins,andminerals.Insomepartsoftheworld,grainsprovidemorethan85%ofthetotaldailycaloricintake.Theinhabitantsofdevelopingcountrieshaveahigherdependencyoncereal-basedfoodsbecausetheyarecheapercomparedtoanimalfoods.

5.1CarbohydrateCerealsareconsideredanexcellentsourceofdigestibleenergyrequiredforgrowthandwork.Thestarch,whichisalmostcompletelydigestedandutilizedinanormalhumansystem,isthemaincaloriecontributor.Anotheradvantageisthatstarchreleasesglucoseataslowerrateintothebloodstream,andthereforehelpsinthecontrolofdiabetes.Nowadays,wholecerealsareviewedastheexcellentsourceofdietaryfiberrequiredfortheproperfunctionofthegastrointestinaltract,andfortheirhealth-promotingeffects,especiallyforpeoplelivinginindustrializedcountriesaroundtheglobe.Theconsumptionofwholecerealsrichindietaryfiberisevenbetterthanrefinedgrainbecauseoftheirlowerglycemicindex.

5.2ProteinCerealsusuallycontainfrom8-12%proteinandhaveagoodrateofproteindigestability(80-90%),butunfortunatelylacklysine,themostimportantandscarceessentialaminoacidinhumannutrition.Therefore,proteinqualityofcerealsislowanditisaffectedbythedigestibilityrateandmainlybytheessentialaminoacidbalance.Nowadays,themalnutritionproblemsthatstillwidelydistributethroughouttheworldaremostalwaysobservedininfantslivinginplaceswherecerealsprovidemostofthedailyfoodintake.Aimingtothereductionofproteinmalnutrition,researchersareactivelybreedingorfurtherimprovingmaize,sorghum,andbarleywiththeaimofobtaininghighlysinecultivars.

5.3VitaminsandmineralsCerealsarelowinfat-solublevitamins(vitaminA,D,EandK)anddevoidofvitaminC.However,theyareagoodsourceofallB-vitaminsexceptB12.ItiscommontoobservevitaminAdeficienciesinpopulationsthatdependoncereals.Thevarioustypesofmillingprocesseslowerfiber,fat,vitamin,andmineralconcentrations,andyieldflourswithahigherrateofstarchandproteindigestibility.Therefore,milling,fermentation,andcookingduringtheprocessoffoodproductionaffectthecompositionandbioavailabilityofmanyimportantnutrients.6.VegetablesandfruitsBecauseofhigherfibercontentandbeneficialphyto-chemicals,vegetablesandFruitsprotectagainstvariouschronicdiseases,suchascardiacdisease,typeIIdiabete,obesityandseveralformsofcancers.Theyimparttheirowncharacteristicflavor,color,andtexturetodiets,andundergochangesduringstorageandcooking.6.1CarbohydrateFruitshavehighwatercontentandlowlevelsofproteinandfat.Theproteinisconcentratedintheseedsandisresistanttodigestioninthesmallintestineandbacterialdegradationinthelargeintestine.However,fruitscontainmostlysugarsandfibers,thatareextensivelyfermentedinthelargeintestine,especiallyapplesandpears,areconcentratedinfructose.Freefructoseispoorlyabsorbedandwouldfunctionsimilartodietaryfiber,escapingabsorptioninthesmallintestinewhilebeingfermentedinthelargeintestine.Therefore,itexplainswhyjuicesofappleandpearareusedtotreatconstipationinchildren.Theproteincontentsofleavesandstemsarehigherthanfruitsandtheycontainlowamountsofsugar.However,rootsandtubersareimportantsourcesofenergyasstarch,whichcontainhighamountsofsugar.Onthecontrary,dietaryfiberoffruitsishigherthanleaves,stems,roots,andtubers.Thecarbohydratecontentoffoodsanddrinksisdiverseandincludesdigestiblecarbohydratesandfiber.Fiberisdefinitelyanactivecomponentoffruitsandvegetablesandareasontocontinuetosupporttheirconsumption.Dietaryfiberonfoodlabelsincludesbothdietaryfiberandfunctionalfiber.Dietaryfiberislistedonthenutritionfactspaneland25gofdietaryfiberistherecommendedamountina2000-kcaldiet.Therefore,wheneverpossible,theentirefruitorvegetable,i.e.,peelandmembrane,shouldbeconsumedtoincreasefiberconsumption.6.2MineralsandvitaminsIncreasedfruitandvegetableconsumptioncanimprovethemineralregulationandreducecardiovasculardiseasesandcertaincancerrisks.Themainelementsinvegetab