糧油加工工藝學 課件 Chapter 7 植物油脂制取與精煉 Vegetable 0ils Processing and Refinement

1Chapter7Vegetable0ilsProcessingandRefinement

植物油脂制取與精煉2教學要求：1.植物油料的化學組成2.不同油脂壓榨方法及其優(yōu)缺點。3一、Introduction（概述）1.DEFINITIONSOFLIPIDS（脂質(zhì)）Lipidsaredefinesas‘‘a(chǎn)widevarietyofnaturalproductsincludingfattyacidsandtheirderivatives,steroids/?ster??d/(類固醇）,terpenes/?t??pi?n/

（萜烯）,carotenoids/k??r?t??n??d/（類胡蘿卜素）,andbileacids（膽汁酸）,whichhaveincommonareadysolubilityinorganicsolventssuchasdiethylether/da??eθ?l//?i?θ?(r)/（乙醚）,hexane/?hekse?n/（己烷）,benzene/?benzi?n/（苯）,chloroform/?kl?r?f??m/（氯仿）,ormethanol/?meθ?n?l/（甲醇）.’’42.LIPIDCLASSIFICATIONS（分類）Classificationoflipidstructuresispossiblebasedon：常溫下物理性質(zhì)

：physicalpropertiesatroomtemperature

(oilsareliquidandfatsaresolid),極性：theirpolarity/p??l?r?ti/(polarandneutrallipids),必要性：theiressentiality/??sen????l?t?/forhumans(essentialandnonessentialfattyacids),結(jié)構(gòu)：ortheirstructure(simpleorcomplex).5Foodscontainanyoralloftheselipidcompounds;however,triacylglycerols/?s?l?ɡl?s?r?l/(TAGs)(甘油三酯)andphospholipids/?f?sf??l?p?d/(PLs)arethemostabundantandimportantones.食物含有任何或所有這些脂類化合物；然而，三酰甘油(TAGs)和磷脂(PLs)是最豐富和最重要的。LiquidTAGsatroomtemperaturearereferredtoasoils,andaregenerallyofplantormarine/m??ri?n/（海的）origin(e.g.,vegetableandmarineoils).SolidTAGsatroomtemperaturearetermedfats,whicharegenerallyofanimalorigin(e.g.,lard豬油andtallow牛脂).2.LIPIDCLASSIFICATIONS（分類）63.VarietiesandCompositionsofVegetableoilseeds（1）Varietiesoilseeds(油料)：Oilcontentabove10%,plantseed,by-products.Twovarieties：Highoilcontentoilseeds,above30%；Low,20%。Peanut,Soybean,Colza/?k?lz?/(菜籽）,Corn,Sunflower,Ricebran.7（2）StructureandCompositionsStructure：Similar，seedcoatoutside,protectembryoandendosperm.embryo(胚)isthemainpartsofseeds,whereamajorityofoillocated.類似地，種皮包在外面，保護胚和胚乳，胚是種子的主要部分，大部分油分布在胚中。Oilsarestoredinprotoplasm/?pr??t?pl?z?m/(原生質(zhì))，whichiscalledspherosomes/?sf??r??s??m/(油體）.油儲存在原生質(zhì)中，這被稱為油體。Storageproteinisconcentratedindiscrete（分離的）bodiesknownasproteinbodies.貯藏蛋白集中在被稱為蛋白體的離散體中。8Fig1MicrostructureofSoybeancotyledon(子葉)CW,PB,Sspherosomes(油體）9CompositionsofOilseedsTheprimaryconstituents/k?n?st?t???nt/arethetriglycerides（甘油三酯）,butalsocontainvaryingamountsofcomponents,consistofphospholipids（磷脂）,tocopherols

/t???k?f?r?lz/（生育酚）,sterols/?ster?lz/（甾醇）,carbohydrates,proteins,andpigmentssuchasgossypol/?ɡ?s??p?l/（棉子酚）,carotene,andchlorophyll/?kl?r?f?l/（葉綠素）.10cottonseed（棉籽）Colza/?k?lz?/(菜籽）Sesame/?ses?mi/（芝麻）11Oiliscomposedof1glyceroland3fattyacids,alsonamedtriglyceride.1)Oil12Fattyacids:saturated/?s?t??re?t?d/(飽和脂肪酸)andunsaturated(不飽和脂肪酸).Commonsaturated:palmitic/p?l?m?t?k/acid(軟脂酸),stearic/st???r?k/acid(硬脂酸),arachicacid(花生酸)

；Commonunsaturated：

oleic/???li??k/acid(油酸),linoleicacid(亞油酸),linolenicacid(亞麻酸),erucic/??ru?s?k/acid(芥酸),DHA(二十二碳六烯酸,EPA（二十碳五烯酸）.13A.碘價Iodine/?a??di?n/

Value(IV)Iodinevalue(IV)measuresthedegreeofunsaturation/??ns?t???re???n/ofalipidandisdefinedasthenumberofgramsofiodineabsorbedby100goflipid.脂中脂肪酸的飽和程度常用碘價反映，碘價用每100克油脂吸收碘的克數(shù)表示。碘價越高，油脂中脂肪酸不飽和程度越高。按碘價不同油脂分成3類:碘價＜80為不干性油non-dryingoil；碘價80~130為半干性油semi-dryingoil；碘價＞130為干性油dryingoil，植物油脂大部分為半干性油~干性油。1415Notexistinpureoil.Notmature/m??t???(r)/oilseeds,storeorprocessabnormal,hydrolysisofoiltoproduce.未成熟的油料種子，貯藏或加工過程異常，油脂水解產(chǎn)生。Acidity/??s?d?ti/increase.Theacidvalue,whichisdefinedasthenumberofmilligramsofKOHrequiredtoneutralize/?nju?tr?la?z/thefreeacidsin1gofsample,isameasureofFFAcontent.酸價用中和1克油脂中的游離脂肪酸所使用的氫氧化鉀的毫克數(shù)。酸價越高，油脂中游離脂肪酸含量越高。B.FreeFattyAcid(FFA)Content16C.Peroxide/p??r?ksa?d

Value（過氧化值）Peroxidevalueisdefinedasthemillimoles/?m?l?m??l/ofperoxidisesperkilogramofsample.

lkg油脂中過氧化物的毫摩爾數(shù)。oxidise/??ks?da?z/使氧化Itistitrimetric/?ta?tr??metr?k/determination(OwenR.Fennema.,1996).

它是滴定法測定。17182)ProteinInsolubleinorganicsolvents.Denaturalization/di?n?t??r?la??ze???n/:Heat,dry,pressure變性：加熱，干燥，壓力Reactionwithsugars50%incakeormeal19

3)Phospholipids磷脂類Thesecompoundsarebetterknownasphosphatides/?f?sf??ta?d/andarefrequentlyreferredto,togetherwithsmallquantitiesofcarbohydratesandresins/?rez?nz/,asgums/ɡ?mz/,whichhaveadverseeffectsonproductqualityandrefinedoilyield.

這些化合物被稱為磷脂，經(jīng)常與少量的碳水化合物和樹脂一起被稱為膠質(zhì)，它們對產(chǎn)品質(zhì)量和精煉油的產(chǎn)量有不利影響。Twocommonphosphatidesoccurringinvegetableoilsarethelecithins/?les?θ?nz/（卵磷脂）andcephalins

/?sef?l?nz/（腦磷脂）植物油中常見的兩種磷脂是卵磷脂和腦磷脂204)PigmentsThecolorbodiesinfatsandoilsincludethecarotenes,whichimpartyellowandredcolorstotheoil;chlorophylls/?kl?r?f?l/,whichgiveitagreenishcast;gossypol/?ɡ?s??p?l/（棉子酚）,whichprovidestheyellowish/?jel????/colortocottonseedoil;脂肪和油中的顏色體包括胡蘿卜素，它賦予油黃色和紅色；葉綠素，呈淡綠色；棉酚，它提供了淡黃色的棉籽油；Thecarotenes,whicharewidelydistributedinfatsandoils,areheatsensitiveandreadilyadsorbedbybleachingearths.

胡蘿卜素廣泛分布在脂肪和油中，它們對熱敏感，很容易被漂白土吸附。215)WaxesRiceBranOil：Solid,sticky,atroomtemperatureThewaxmaybecomeinsolubleatcoldtemperaturesandmaketheoilunattractivelycloudy.在寒冷的溫度下，蠟可能變得不溶，使油變得不吸引人。Thesewaxesmustberemovedduringlatteroil-refiningsteps,oftenbywinterization/?w?nt??ra?ze???n/（冬化）orcoldcentrifugation/sentr?fj??ɡe???n/。這些蠟必須在后期煉油步驟中去除，通常是通過冬化或冷離心226Vitamins

Tocopherols/t???k?f?r?lz/(VitaminE)Theseantioxidantsinhibitlipidoxidationinfoodsbystabilizinghydroperoxyl（羥自由基）andotherfreeradicals.peroxyl/p?'r?ksil/過氧化氫Thestabilityofmanyvegetableoilshasbeencreditedtothepresenceofthesenaturalantioxidants.23二、Samplepreparationforextractingvegetableoils

植物油料的預處理Pretreatmentsstorage（儲藏)→cleaning（清理除雜）→dehulling（剝殼）→cracking（破碎）→conditioning（軟化）→flaking（軋坯）

→cooking（蒸炒)241.SeedStorageOilseedsareoftenharvestedatmoisturecontentshigherthanlevelsthatallowforlongtermstorageandmustbedriedforsafestorage.242.CleaningUnlessremovedbycleaningoperations,foreignmatterreducesoilandproteincontentsandincreaseswear（損耗）anddamagetoexpensiveprocessingequipment;inaddition,foreignmattermayadverselyaffectoilquality(especiallycolor).252.CleaningMagnets/?m?ɡn?t/（磁鐵）areplacedjustaheadofprocessingequipmenttopreventdamage.Vibratingand/orshakerscreenswithorwithoutaspiration/??sp??re??(?)n/areusedtoremovestems/stem/,pods（豆莢）,leaves,splits,brokengrain,dirt,andextraneous/?k?stre?ni?s/seeds.

帶或不帶吸氣的振動和/或振動篩用于除去莖稈、莢果、葉子、裂縫、碎谷物、污垢和外來種子。263.Dehulling（剝殼）Removingthehullreducestheamountofmaterialthatmustbehandled,extracted,anddesolventized（脫溶）,thusincreasingdownstream（下游）plantcapacity（工廠設(shè)備生產(chǎn)能力）.Theequipmentcutsorbreaksthehulltofreethemeat（種仁）,astepoftenreferredtoasecortication/di??k??t??ke?t?n/（脫皮）.Hull/meatseparationsystemscomprising/k?m?pra?z/oneormoreshakerscreens（振動篩）,aspirators/??sp?re?t?(r)/,andgravity/?ɡr?v?ti/tables（重力分選臺）areeffectivebecausethehullisoftenlargerandalmostalwayslowerindensity/?dens?ti/andmorebuoyant/?b???nt/（有浮力的）thantheoil-richmeat.274Particlesizereduction油料的破碎Theoilextractionprocessisfacilitated/f??s?l?te?t?d/bythereductionoftheseedtosmallparticles.Sizereductiontodisrupttheoil-bearingcellscanbeaccomplishedbygrinding/?ɡra?nd??/orrolling/?r??l??/theseedstoproduceflakes.縮小尺寸至粉碎含油細胞可以通過研磨或滾動種子來產(chǎn)生薄片來完成。285.Conditioning油料的軟化AdjustwatercontentandtemperatureofoilseedsProducesuitableplasticity/pl??st?s?ti/（可塑性）Easyfornextprocedureflaking（軋坯）Heattheseed70°C-80°Cfor20-30min,whilemaintaining10.5%–11.5%moisture.296Flaking油料的軋坯Usemechanical

forcetochangetheshapefromparticles（顆粒）toflakes（片）.Theflakedmaterialmusthavetenacious

/t??ne???s/（強的）,thinstructure,withporosity/p???r?s?ti/（多孔性）thatallowstransportoftheoilormiscella/mi'sel?/(solvent–oilmixture)（混合油）.Theflakethicknessinfluencestherateofoilextraction.Themeatsareflakedwithsmooth-surfacedrollermillstolowthickness0.25mmwithoutproducingexcessivefines,whichadverselyaffect.millimeter/?m?limi?t?(r)/用光滑表面的輥磨機將果仁切成薄片，厚度為0.25毫米，而不會產(chǎn)生過多的細粉，這對其他操作產(chǎn)生不利影響。307

Heatingorcooking油料的蒸炒Cookingtemperaturescanvarywiththeseedtypeandmayrangefrom80to105°C.

Properheatingorcookingresultsinthecompletebreakdownoftheoilcells,coagulation/k????ɡju?le??(?)n/凝固oftheproteinstofacilitatetheoilandmealseparation,insolubilizationofthephospholipids（磷脂）,destructionofmolds/m??ldz/霉菌

andbacteria,inactivationofenzymes.31三、

Extractionmethods(油脂制?。㏕hreegeneraltypesofprocessesareusedtocrushoilseeds:hardpressing（機械壓榨法）,prepresssolventextraction（預榨浸出法）,anddirectsolventextraction（溶劑浸出法）.提取工藝的選擇主要取決于原料的含油量、允許的餐食殘油量、允許的蛋白質(zhì)變性量、可用的投資資本量，以及有關(guān)揮發(fā)性有機化合物(VOCs)排放的當?shù)丨h(huán)境法。32Hardpressing,or，Mechanicalpressing(HardScrewPressing)（螺旋壓榨）Theoldestoilrecoverymethodishardpressing（壓榨）,wheretheseedispressed,usuallyaftervariouspretreatmentstoenhanceoilrecovery,tosqueeze（榨取）theoilfromthesolidsknownascake.最傳統(tǒng)的油回收方法是硬壓榨，種子被壓榨，通常是在各種預處理后，以提高油回收率，將油從餅中擠壓出來。1.Hardpressing機械壓榨法2.PrepressSolventExtraction預壓溶劑萃取Foralongtime,theruleofthumb

/θ?m/（拇指法則或經(jīng)驗法則）hasbeenthatmaterialscontaining>30%oilrequirepressing,eitherhardpressingorprepressing,beforesolventextraction.Consequently,lessoilisextractedandthroughputisincreased.Usually,theoilcontentofprepresscakeis15%–18%,andthepartiallydeoiledcakeisthenextractedwithsolvent.通常，預榨餅的含油量為15%-18%，然后用溶劑提取部分脫油的餅。2.PrepressSolventExtraction預壓溶劑萃取浸出法制油工藝的基本過程:油料坯或預榨餅浸于選定的溶劑中→油脂溶解在溶劑內(nèi)(成為混合油)→混合油與固體殘渣(粕)分離混合油再按不同的沸點進行蒸發(fā)、汽提。使溶劑汽化變成蒸氣與油分離，從而制得油脂(浸出毛油)。溶劑蒸氣則經(jīng)過冷凝、冷卻回收后繼續(xù)循環(huán)使用。粕中也含有定量的溶劑、經(jīng)脫溶烘干處理后即得干粕，脫溶烘干過程中揮發(fā)出的溶劑蒸氣仍經(jīng)冷凝、冷卻回收。35Today,hexanes/?hekse?n/己烷(ablendofabout60%n-hexanewithotherhexaneisomers/?a?s?m?(r)/)arethesolventofchoice,althoughmanyothersolventswereusedduringdevelopmentofsolventextractiontechnologies.Theprimarydisadvantageofhexaneisitsflammability/?fl?m??b?l?ti/（可燃性）andapricestructureandsupplythataretiedtopetroleum/p??tr??li?m/prices.四、油脂精煉REFINING1.BACKGROUNDConsumersusuallywantbland-flavored（風味平淡)orflavor-neutral,light-colored,andphysicallyandoxidativelystableoils.消費者通常想要口味清淡或味道中性、淺色、物理和氧化穩(wěn)定的油。Crudeoilsarenotusuallyconsideredtobeedibleuntilnumerousnonglyceride(非甘油酯化合物)compoundshavebeenremovedthroughoperationscollectivelyknownasrefining.However,someoils,suchasolive(橄欖油),tallow(牛油),andlard(豬油),havebeenconsumedwithoutrefining.371.BACKGROUNDUndesirablecomponentsofcrudeoilsincludesmallamountsofproteinorothersolids,phosphatides,undesirablenaturalflavorsandodors,freefattyacids,pigments,waxes,sulfur-containingcompounds(canola/k??n??l?/（加拿大油菜）andrapeseed/?re?psi?d/（油菜籽）),tracesolventresidue/?rez?dju?/微量溶劑殘留物,andwater.However,notallnonglyceridecompoundsaredeleterious/?del??t??ri?s/（有害的）.Tocopherols/t???k?f?r?lz/（生育酚）protecttheoilagainstautoxidation/???t?ks??de???n/（自然氧化）andprovidevitaminEactivity,andβ-caroteneprovidesvitaminAactivity.Otherphenolic/f??n?l?k/compounds,suchassesamol（芝麻酚）insesameoil,actasnaturalantioxidants.381.BACKGROUNDTherearetwomajortypesofrefining:chemicalandphysical.Themajorstepsinvolvedinchemialrefiningincludedegumming/di??ɡ?m??/（脫膠）,neutralizing（中和）,bleaching（脫色）,anddeodorizing/di????d?ra?z??/（脫臭）.Physicalrefiningremovesfreefattyacidsandflavorsbydistillation/?d?st??le??n/（蒸餾）,tocombinethestepsofneutralizationanddeodorizationintooneoperation.RBD(Refine,Bleach,Deodorize)oil（精煉油）referstooilthathasbeenalkalirefined,bleached,anddeodorizedoroilthathasbeenphysicallyrefined.392.DEGUMMINGDegummingisawater-washingprocesstoremovephosphatides.Unlessremoved,phosphatidescanspontaneously/sp?n?te?ni?sli/（自然地）hydratefrommoistureintheairduringstorage.Inthecasesofoilsrichinphosphatides,suchassoybeanandcanolaoils菜籽油,degummingisusuallyaseparateoperation.Hydrationmakesphosphatidesinsolubleintheoil,andtheyprecipitate/pr??s?p?te?t/沉淀.403.NEUTRALIZATION(ALKALIREFINING)Thetermneutralizationcomesfromneutralizingthenaturalacidity/??s?d?ti/oftheoilemanating/?em?ne?t??/from（源自于）thepresenceoffreefattyacids.Neutralizationisthemostimportantoperationinrefiningedibleoils.Neutralizationisachievedbythereactionofthefreefattyacidwithcaustic/?k??st?k/soda/?s??d?/（苛性鈉）(sodiumhydroxide/ha??dr?ksa?d/氫氧化鈉)toformsoapreferredtoassoapstock（皂腳）.413.NEUTRALIZATION(ALKALIREFINING)Saponification/s??p?n?f??ke???n/（皂化）referstoreactionsbetweenglyceridesandsodiumhydroxidealsotoformsoaps.Neutralizationmustbedonecorrectlyorsomeoftheglycerideswillbesaponified,resultinginincreasedrefiningloss.saponify/s??p?n?fa?/使皂化Theoil,lowinacidvalue,istermedneutraloil.423.NEUTRALIZATION(ALKALIREFINING)Soapstock皂腳isremovedfromtheoilbyusingcontinuous,disk-typecentrifuges.Refinedoilisthenwashedwithsoftwater(10%–20%)at90℃andrecentrifugedtoremovemostofthesoap.Theremainingsoapisremovedduringbleaching.434.DRYINGThewatersaturation/?s?t???re??n/levelinediblefatsandoilsisabout0.8%,butoilsshouldcontain<0.3%.Vegetableoilsmustbedriedbeforeheatingforprolongedperiodstohightemperaturesasinhydrogenationanddeodorization;otherwise,hydrolysiscanoccur,recreatingfreefattyacids.Dryingisaccomplishedbysprayingthehotoil(115℃)intoavacuumtower(15mmHgmillimetre(s)ofmercury/?m??kj?ri/absolutevacuum).Themoisturecontentofthedegummedandneutralizedoilisreducedto<0.1%.445.BLEACHINGTheprimarypurposeofbleachingistoimproveoilcolorbyremovingpigmentswithneutralclays（中性白土）,activatedearths（活性土）,syntheticsilicates（硅酸鹽）,silicagel（硅膠）,andcarbonblack（黑煙末）.Otherbenefitsofbleachingarethebreakdownofperoxides（過氧化物）andcleanupofresidualtracesofsoapsandphosphatides.Theprimarypigmentsofconcernarethosethatgivered-brown(carotenoids,xanthophyll（葉黃色素）,gossypol（棉子酚）,etc.)orgreencolors(chlorophyll葉綠素).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（羅維朋色度計）,usuallyinredandyellowterms.Mostfinishededibleoilsarelessthan10yellowand2.5red,withhigh-gradeshorteningsbeinglessthan1.0red.496.DEWAXINGWaxescanharmtheappearanceofbottledoilbycausingunsightlycloudinessorsediments.Corn,ricebran,safflower（紅花）,sesame,andsunflowerseedoilsarenotorious（臭名昭著的）forproblematichighwaxcontents(0.2%–3.0%)andmustundergodewaxing;occasionallycanolaoilalsohaswaxproblems.506.DEWAXINGWaxescanberemovedbycoolingtheoilto6℃–8℃andfilteringorcentrifugingatc