粮油加工工艺学 课件 Chapter 7 植物油脂制取与精炼 Vegetable 0ils Processing and Refinement

1Chapter7Vegetable0ilsProcessingandRefinement

植物油脂制取与精炼2教学要求：1.植物油料的化学组成2.不同油脂压榨方法及其优缺点。3一、Introduction（概述）1.DEFINITIONSOFLIPIDS（脂质）Lipidsaredefinesas‘‘awidevarietyofnaturalproductsincludingfattyacidsandtheirderivatives,steroids/ˈsterɔɪd/(类固醇）,terpenes/ˈtɜːpiːn/

（萜烯）,carotenoids/kəˈrɒtɪˌnɔɪd/（类胡萝卜素）,andbileacids（胆汁酸）,whichhaveincommonareadysolubilityinorganicsolventssuchasdiethylether/daɪˈeθɪl//ˈiːθə(r)/（乙醚）,hexane/ˈhekseɪn/（己烷）,benzene/ˈbenziːn/（苯）,chloroform/ˈklɒrəfɔːm/（氯仿）,ormethanol/ˈmeθənɒl/（甲醇）.’’42.LIPIDCLASSIFICATIONS（分类）Classificationoflipidstructuresispossiblebasedon：常温下物理性质

：physicalpropertiesatroomtemperature

(oilsareliquidandfatsaresolid),极性：theirpolarity/pəˈlærəti/(polarandneutrallipids),必要性：theiressentiality/ɪˌsenʃɪˈælətɪ/forhumans(essentialandnonessentialfattyacids),结构：ortheirstructure(simpleorcomplex).5Foodscontainanyoralloftheselipidcompounds;however,triacylglycerols/æsɪlˈɡlɪsərɒl/(TAGs)(甘油三酯)andphospholipids/ˌfɒsfəˈlɪpɪd/(PLs)arethemostabundantandimportantones.食物含有任何或所有这些脂类化合物；然而，三酰甘油(TAGs)和磷脂(PLs)是最丰富和最重要的。LiquidTAGsatroomtemperaturearereferredtoasoils,andaregenerallyofplantormarine/məˈriːn/（海的）origin(e.g.,vegetableandmarineoils).SolidTAGsatroomtemperaturearetermedfats,whicharegenerallyofanimalorigin(e.g.,lard猪油andtallow牛脂).2.LIPIDCLASSIFICATIONS（分类）63.VarietiesandCompositionsofVegetableoilseeds（1）Varietiesoilseeds(油料)：Oilcontentabove10%,plantseed,by-products.Twovarieties：Highoilcontentoilseeds,above30%；Low,20%。Peanut,Soybean,Colza/ˈkɒlzə/(菜籽）,Corn,Sunflower,Ricebran.7（2）StructureandCompositionsStructure：Similar，seedcoatoutside,protectembryoandendosperm.embryo(胚)isthemainpartsofseeds,whereamajorityofoillocated.类似地，种皮包在外面，保护胚和胚乳，胚是种子的主要部分，大部分油分布在胚中。Oilsarestoredinprotoplasm/ˈprəʊtəplæzəm/(原生质)，whichiscalledspherosomes/ˈsfɪərəʊsəʊm/(油体）.油储存在原生质中，这被称为油体。Storageproteinisconcentratedindiscrete（分离的）bodiesknownasproteinbodies.贮藏蛋白集中在被称为蛋白体的离散体中。8Fig1MicrostructureofSoybeancotyledon(子叶)CW,PB,Sspherosomes(油体）9CompositionsofOilseedsTheprimaryconstituents/kənˈstɪtʃʊənt/arethetriglycerides（甘油三酯）,butalsocontainvaryingamountsofcomponents,consistofphospholipids（磷脂）,tocopherols

/təʊˈkɒfərɒlz/（生育酚）,sterols/ˈsterɒlz/（甾醇）,carbohydrates,proteins,andpigmentssuchasgossypol/ˈɡɒsɪˌpɒl/（棉子酚）,carotene,andchlorophyll/ˈklɒrəfɪl/（叶绿素）.10cottonseed（棉籽）Colza/ˈkɒlzə/(菜籽）Sesame/ˈsesəmi/（芝麻）11Oiliscomposedof1glyceroland3fattyacids,alsonamedtriglyceride.1)Oil12Fattyacids:saturated/ˈsætʃəreɪtɪd/(饱和脂肪酸)andunsaturated(不饱和脂肪酸).Commonsaturated:palmitic/pælˈmɪtɪk/acid(软脂酸),stearic/stɪˈærɪk/acid(硬脂酸),arachicacid(花生酸)

；Commonunsaturated：

oleic/əʊˈliːɪk/acid(油酸),linoleicacid(亚油酸),linolenicacid(亚麻酸),erucic/ɪˈruːsɪk/acid(芥酸),DHA(二十二碳六烯酸,EPA（二十碳五烯酸）.13A.碘价Iodine/ˈaɪədiːn/

Value(IV)Iodinevalue(IV)measuresthedegreeofunsaturation/ˌʌnsætʃəˈreɪʃən/ofalipidandisdefinedasthenumberofgramsofiodineabsorbedby100goflipid.脂中脂肪酸的饱和程度常用碘价反映，碘价用每100克油脂吸收碘的克数表示。碘价越高，油脂中脂肪酸不饱和程度越高。按碘价不同油脂分成3类:碘价＜80为不干性油non-dryingoil；碘价80~130为半干性油semi-dryingoil；碘价＞130为干性油dryingoil，植物油脂大部分为半干性油~干性油。1415Notexistinpureoil.Notmature/məˈtʃʊə(r)/oilseeds,storeorprocessabnormal,hydrolysisofoiltoproduce.未成熟的油料种子，贮藏或加工过程异常，油脂水解产生。Acidity/əˈsɪdəti/increase.Theacidvalue,whichisdefinedasthenumberofmilligramsofKOHrequiredtoneutralize/ˈnjuːtrəlaɪz/thefreeacidsin1gofsample,isameasureofFFAcontent.酸价用中和1克油脂中的游离脂肪酸所使用的氢氧化钾的毫克数。酸价越高，油脂中游离脂肪酸含量越高。B.FreeFattyAcid(FFA)Content16C.Peroxide/pəˈrɒksaɪd

Value（过氧化值）Peroxidevalueisdefinedasthemillimoles/ˈmɪlɪməʊl/ofperoxidisesperkilogramofsample.

lkg油脂中过氧化物的毫摩尔数。oxidise/ˈɒksɪdaɪz/使氧化Itistitrimetric/ˌtaɪtrɪˈmetrɪk/determination(OwenR.Fennema.,1996).

它是滴定法测定。17182)ProteinInsolubleinorganicsolvents.Denaturalization/diːnætʃərəlaɪˈzeɪʃən/:Heat,dry,pressure变性：加热，干燥，压力Reactionwithsugars50%incakeormeal19

3)Phospholipids磷脂类Thesecompoundsarebetterknownasphosphatides/ˈfɒsfəˌtaɪd/andarefrequentlyreferredto,togetherwithsmallquantitiesofcarbohydratesandresins/ˈrezɪnz/,asgums/ɡʌmz/,whichhaveadverseeffectsonproductqualityandrefinedoilyield.

这些化合物被称为磷脂，经常与少量的碳水化合物和树脂一起被称为胶质，它们对产品质量和精炼油的产量有不利影响。Twocommonphosphatidesoccurringinvegetableoilsarethelecithins/ˈlesɪθɪnz/（卵磷脂）andcephalins

/ˈsefəlɪnz/（脑磷脂）植物油中常见的两种磷脂是卵磷脂和脑磷脂204)PigmentsThecolorbodiesinfatsandoilsincludethecarotenes,whichimpartyellowandredcolorstotheoil;chlorophylls/ˈklɒrəfɪl/,whichgiveitagreenishcast;gossypol/ˈɡɒsɪˌpɒl/（棉子酚）,whichprovidestheyellowish/ˈjeləʊɪʃ/colortocottonseedoil;脂肪和油中的颜色体包括胡萝卜素，它赋予油黄色和红色；叶绿素，呈淡绿色；棉酚，它提供了淡黄色的棉籽油；Thecarotenes,whicharewidelydistributedinfatsandoils,areheatsensitiveandreadilyadsorbedbybleachingearths.

胡萝卜素广泛分布在脂肪和油中，它们对热敏感，很容易被漂白土吸附。215)WaxesRiceBranOil：Solid,sticky,atroomtemperatureThewaxmaybecomeinsolubleatcoldtemperaturesandmaketheoilunattractivelycloudy.在寒冷的温度下，蜡可能变得不溶，使油变得不吸引人。Thesewaxesmustberemovedduringlatteroil-refiningsteps,oftenbywinterization/ˈwɪntəˌraɪzeɪʃən/（冬化）orcoldcentrifugation/sentrɪfjʊˈɡeɪʃən/。这些蜡必须在后期炼油步骤中去除，通常是通过冬化或冷离心226Vitamins

Tocopherols/təʊˈkɒfərɒlz/(VitaminE)Theseantioxidantsinhibitlipidoxidationinfoodsbystabilizinghydroperoxyl（羟自由基）andotherfreeradicals.peroxyl/pə'rɔksil/过氧化氢Thestabilityofmanyvegetableoilshasbeencreditedtothepresenceofthesenaturalantioxidants.23二、Samplepreparationforextractingvegetableoils

植物油料的预处理Pretreatmentsstorage（储藏)→cleaning（清理除杂）→dehulling（剥壳）→cracking（破碎）→conditioning（软化）→flaking（轧坯）

→cooking（蒸炒)241.SeedStorageOilseedsareoftenharvestedatmoisturecontentshigherthanlevelsthatallowforlongtermstorageandmustbedriedforsafestorage.242.CleaningUnlessremovedbycleaningoperations,foreignmatterreducesoilandproteincontentsandincreaseswear（损耗）anddamagetoexpensiveprocessingequipment;inaddition,foreignmattermayadverselyaffectoilquality(especiallycolor).252.CleaningMagnets/ˈmæɡnət/（磁铁）areplacedjustaheadofprocessingequipmenttopreventdamage.Vibratingand/orshakerscreenswithorwithoutaspiration/ˌæspəˈreɪʃ(ə)n/areusedtoremovestems/stem/,pods（豆荚）,leaves,splits,brokengrain,dirt,andextraneous/ɪkˈstreɪniəs/seeds.

带或不带吸气的振动和/或振动筛用于除去茎秆、荚果、叶子、裂缝、碎谷物、污垢和外来种子。263.Dehulling（剥壳）Removingthehullreducestheamountofmaterialthatmustbehandled,extracted,anddesolventized（脱溶）,thusincreasingdownstream（下游）plantcapacity（工厂设备生产能力）.Theequipmentcutsorbreaksthehulltofreethemeat（种仁）,astepoftenreferredtoasecortication/diːˌkɔːtɪˈkeɪtʃn/（脱皮）.Hull/meatseparationsystemscomprising/kəmˈpraɪz/oneormoreshakerscreens（振动筛）,aspirators/ˈæspɪreɪtə(r)/,andgravity/ˈɡrævəti/tables（重力分选台）areeffectivebecausethehullisoftenlargerandalmostalwayslowerindensity/ˈdensəti/andmorebuoyant/ˈbɔɪənt/（有浮力的）thantheoil-richmeat.274Particlesizereduction油料的破碎Theoilextractionprocessisfacilitated/fəˈsɪlɪteɪtɪd/bythereductionoftheseedtosmallparticles.Sizereductiontodisrupttheoil-bearingcellscanbeaccomplishedbygrinding/ˈɡraɪndɪŋ/orrolling/ˈrəʊlɪŋ/theseedstoproduceflakes.缩小尺寸至粉碎含油细胞可以通过研磨或滚动种子来产生薄片来完成。285.Conditioning油料的软化AdjustwatercontentandtemperatureofoilseedsProducesuitableplasticity/plæˈstɪsəti/（可塑性）Easyfornextprocedureflaking（轧坯）Heattheseed70°C-80°Cfor20-30min,whilemaintaining10.5%–11.5%moisture.296Flaking油料的轧坯Usemechanical

forcetochangetheshapefromparticles（颗粒）toflakes（片）.Theflakedmaterialmusthavetenacious

/təˈneɪʃəs/（强的）,thinstructure,withporosity/pɔːˈrɒsəti/（多孔性）thatallowstransportoftheoilormiscella/mi'selə/(solvent–oilmixture)（混合油）.Theflakethicknessinfluencestherateofoilextraction.Themeatsareflakedwithsmooth-surfacedrollermillstolowthickness0.25mmwithoutproducingexcessivefines,whichadverselyaffect.millimeter/ˈmɪlimiːtə(r)/用光滑表面的辊磨机将果仁切成薄片，厚度为0.25毫米，而不会产生过多的细粉，这对其他操作产生不利影响。307

Heatingorcooking油料的蒸炒Cookingtemperaturescanvarywiththeseedtypeandmayrangefrom80to105°C.

Properheatingorcookingresultsinthecompletebreakdownoftheoilcells,coagulation/kəʊˌæɡjuˈleɪʃ(ə)n/凝固oftheproteinstofacilitatetheoilandmealseparation,insolubilizationofthephospholipids（磷脂）,destructionofmolds/məʊldz/霉菌

andbacteria,inactivationofenzymes.31三、

Extractionmethods(油脂制取）Threegeneraltypesofprocessesareusedtocrushoilseeds:hardpressing（机械压榨法）,prepresssolventextraction（预榨浸出法）,anddirectsolventextraction（溶剂浸出法）.提取工艺的选择主要取决于原料的含油量、允许的餐食残油量、允许的蛋白质变性量、可用的投资资本量，以及有关挥发性有机化合物(VOCs)排放的当地环境法。32Hardpressing,or，Mechanicalpressing(HardScrewPressing)（螺旋压榨）Theoldestoilrecoverymethodishardpressing（压榨）,wheretheseedispressed,usuallyaftervariouspretreatmentstoenhanceoilrecovery,tosqueeze（榨取）theoilfromthesolidsknownascake.最传统的油回收方法是硬压榨，种子被压榨，通常是在各种预处理后，以提高油回收率，将油从饼中挤压出来。1.Hardpressing机械压榨法2.PrepressSolventExtraction预压溶剂萃取Foralongtime,theruleofthumb

/θʌm/（拇指法则或经验法则）hasbeenthatmaterialscontaining>30%oilrequirepressing,eitherhardpressingorprepressing,beforesolventextraction.Consequently,lessoilisextractedandthroughputisincreased.Usually,theoilcontentofprepresscakeis15%–18%,andthepartiallydeoiledcakeisthenextractedwithsolvent.通常，预榨饼的含油量为15%-18%，然后用溶剂提取部分脱油的饼。2.PrepressSolventExtraction预压溶剂萃取浸出法制油工艺的基本过程:油料坯或预榨饼浸于选定的溶剂中→油脂溶解在溶剂内(成为混合油)→混合油与固体残渣(粕)分离混合油再按不同的沸点进行蒸发、汽提。使溶剂汽化变成蒸气与油分离，从而制得油脂(浸出毛油)。溶剂蒸气则经过冷凝、冷却回收后继续循环使用。粕中也含有定量的溶剂、经脱溶烘干处理后即得干粕，脱溶烘干过程中挥发出的溶剂蒸气仍经冷凝、冷却回收。35Today,hexanes/ˈhekseɪn/己烷(ablendofabout60%n-hexanewithotherhexaneisomers/ˈaɪsəmə(r)/)arethesolventofchoice,althoughmanyothersolventswereusedduringdevelopmentofsolventextractiontechnologies.Theprimarydisadvantageofhexaneisitsflammability/ˌflæməˈbɪləti/（可燃性）andapricestructureandsupplythataretiedtopetroleum/pəˈtrəʊliəm/prices.四、油脂精炼REFINING1.BACKGROUNDConsumersusuallywantbland-flavored（风味平淡)orflavor-neutral,light-colored,andphysicallyandoxidativelystableoils.消费者通常想要口味清淡或味道中性、浅色、物理和氧化稳定的油。Crudeoilsarenotusuallyconsideredtobeedibleuntilnumerousnonglyceride(非甘油酯化合物)compoundshavebeenremovedthroughoperationscollectivelyknownasrefining.However,someoils,suchasolive(橄榄油),tallow(牛油),andlard(猪油),havebeenconsumedwithoutrefining.371.BACKGROUNDUndesirablecomponentsofcrudeoilsincludesmallamountsofproteinorothersolids,phosphatides,undesirablenaturalflavorsandodors,freefattyacids,pigments,waxes,sulfur-containingcompounds(canola/kəˈnəʊlə/（加拿大油菜）andrapeseed/ˈreɪpsiːd/（油菜籽）),tracesolventresidue/ˈrezɪdjuː/微量溶剂残留物,andwater.However,notallnonglyceridecompoundsaredeleterious/ˌdeləˈtɪəriəs/（有害的）.Tocopherols/təʊˈkɒfərɒlz/（生育酚）protecttheoilagainstautoxidation/ɔːˌtɒksɪˈdeɪʃən/（自然氧化）andprovidevitaminEactivity,andβ-caroteneprovidesvitaminAactivity.Otherphenolic/fɪˈnɒlɪk/compounds,suchassesamol（芝麻酚）insesameoil,actasnaturalantioxidants.381.BACKGROUNDTherearetwomajortypesofrefining:chemicalandphysical.Themajorstepsinvolvedinchemialrefiningincludedegumming/diːˈɡʌmɪŋ/（脱胶）,neutralizing（中和）,bleaching（脱色）,anddeodorizing/diːˈəʊdəraɪzɪŋ/（脱臭）.Physicalrefiningremovesfreefattyacidsandflavorsbydistillation/ˌdɪstɪˈleɪʃn/（蒸馏）,tocombinethestepsofneutralizationanddeodorizationintooneoperation.RBD(Refine,Bleach,Deodorize)oil（精炼油）referstooilthathasbeenalkalirefined,bleached,anddeodorizedoroilthathasbeenphysicallyrefined.392.DEGUMMINGDegummingisawater-washingprocesstoremovephosphatides.Unlessremoved,phosphatidescanspontaneously/spɒnˈteɪniəsli/（自然地）hydratefrommoistureintheairduringstorage.Inthecasesofoilsrichinphosphatides,suchassoybeanandcanolaoils菜籽油,degummingisusuallyaseparateoperation.Hydrationmakesphosphatidesinsolubleintheoil,andtheyprecipitate/prɪˈsɪpɪteɪt/沉淀.403.NEUTRALIZATION(ALKALIREFINING)Thetermneutralizationcomesfromneutralizingthenaturalacidity/əˈsɪdəti/oftheoilemanating/ˈeməneɪtɪŋ/from（源自于）thepresenceoffreefattyacids.Neutralizationisthemostimportantoperationinrefiningedibleoils.Neutralizationisachievedbythereactionofthefreefattyacidwithcaustic/ˈkɔːstɪk/soda/ˈsəʊdə/（苛性钠）(sodiumhydroxide/haɪˈdrɒksaɪd/氢氧化钠)toformsoapreferredtoassoapstock（皂脚）.413.NEUTRALIZATION(ALKALIREFINING)Saponification/səˌpɒnɪfɪˈkeɪʃən/（皂化）referstoreactionsbetweenglyceridesandsodiumhydroxidealsotoformsoaps.Neutralizationmustbedonecorrectlyorsomeoftheglycerideswillbesaponified,resultinginincreasedrefiningloss.saponify/səˈpɒnɪfaɪ/使皂化Theoil,lowinacidvalue,istermedneutraloil.423.NEUTRALIZATION(ALKALIREFINING)Soapstock皂脚isremovedfromtheoilbyusingcontinuous,disk-typecentrifuges.Refinedoilisthenwashedwithsoftwater(10%–20%)at90℃andrecentrifugedtoremovemostofthesoap.Theremainingsoapisremovedduringbleaching.434.DRYINGThewatersaturation/ˌsætʃəˈreɪʃn/levelinediblefatsandoilsisabout0.8%,butoilsshouldcontain<0.3%.Vegetableoilsmustbedriedbeforeheatingforprolongedperiodstohightemperaturesasinhydrogenationanddeodorization;otherwise,hydrolysiscanoccur,recreatingfreefattyacids.Dryingisaccomplishedbysprayingthehotoil(115℃)intoavacuumtower(15mmHgmillimetre(s)ofmercury/ˈmɜːkjəri/absolutevacuum).Themoisturecontentofthedegummedandneutralizedoilisreducedto<0.1%.445.BLEACHINGTheprimarypurposeofbleachingistoimproveoilcolorbyremovingpigmentswithneutralclays（中性白土）,activatedearths（活性土）,syntheticsilicates（硅酸盐）,silicagel（硅胶）,andcarbonblack（黑烟末）.Otherbenefitsofbleachingarethebreakdownofperoxides（过氧化物）andcleanupofresidualtracesofsoapsandphosphatides.Theprimarypigmentsofconcernarethosethatgivered-brown(carotenoids,xanthophyll（叶黄色素）,gossypol（棉子酚）,etc.)orgreencolors(chlorophyll叶绿素).455.BLEACHINGTheprocessisgenerallydoneundervacuumbecausetheusualbleachingclayscancatalyzeoxidationinthepresenceofair(oroxygen).Adsorbentismixedwithhotoil(80℃–110℃)for15–30mintoformaslurry.Mixingenhancesoilcontactwiththeadsorbent.Thepigmentsareadsorbedontothesurfacesofvariousclaysorearths(somemaybeactivatedbytreatmentwithacid),evensometimesactivatedcarbon（活性炭）,andthesolidsareremovedbyfiltration.46FIGUREProcessflowsheetforvacuumbleaching.475.BLEACHINGAbout0.2%–2%bleachingclayisusuallyused;thepreciseamountdependsupontheamountofpigmentspresent.Atthelowend,0.2%–0.4%isusedforsoybeanoil,whereasricebranoilrequiresconsiderablymore(3%–5%).Inadditiontoremovingpigmentsandresidualsoap,bleachingtakesouttracemetalsandsomeoxidationproducts.485.BLEACHINGEdibleoilsshouldbepaleyellow.ColorismeasuredbytheLovibondtintometer（罗维朋色度计）,usuallyinredandyellowterms.Mostfinishededibleoilsarelessthan10yellowand2.5red,withhigh-gradeshorteningsbeinglessthan1.0red.496.DEWAXINGWaxescanharmtheappearanceofbottledoilbycausingunsightlycloudinessorsediments.Corn,ricebran,safflower（红花）,sesame,andsunflowerseedoilsarenotorious（臭名昭著的）forproblematichighwaxcontents(0.2%–3.0%)andmustundergodewaxing;occasionallycanolaoilalsohaswaxproblems.506.DEWAXINGWaxescanberemovedbycoolingtheoilto6℃–8℃andfilteringorcentrifugingatc