糧油加工工藝學(xué) 課件 Chapter 4 小麥制粉Wheat processing technology

Chapter4小麥制粉

(Flourmilling)1.1小麥工藝品質(zhì)

1.1.1小麥分類小麥硬度指數(shù)hardnessindex在規(guī)定條件下粉碎小麥樣品，留存在篩網(wǎng)上的樣品占試樣的質(zhì)量百分數(shù)，簡稱HI。1.1小麥工藝品質(zhì)

1.1.1小麥分類硬度指數(shù)越大，表明小麥硬度越高，反之表明小麥硬度越低。小麥硬度指數(shù)測定儀中華人民共和國國家標準-小麥GB1351-2008Thefollowingtypesofwheatareclassifiedbasedprimarilyoncolor,hardnessofthekernel根據(jù)小麥的粒質(zhì)和皮色分為以下五類：硬質(zhì)白小麥(Hardwhite)：種皮為白色或黃白色的麥粒不低于90%，硬度指數(shù)不低于60%的小麥。軟質(zhì)白小麥(Softwhite)：種皮為白色或黃白色的麥粒不低于90%，硬度指數(shù)不高于45%的小麥。硬質(zhì)紅小麥(Hardred)：種皮為深紅色或紅褐色的麥粒不低于90%，硬度指數(shù)不低于60%的小麥。軟質(zhì)紅小麥(Softred)：種皮為深紅色或紅褐色的麥粒不低于90%，硬度指數(shù)不高于45%的小麥。混合小麥（mix)：不符合上述四種規(guī)定的小麥。1.1.2小麥的加工品質(zhì)Fig.3.1Thestructureofwheatgranule1)皮層BranLayer14%ofkernelSeveralthinlayerContainsaleurone/?l???r??n/layer(糊粉層）Viable（能自行發(fā)育的）,protectedlayer,surroundsendospermenzymeactivityContains:protein,lipid,minerals,vitamins,phenolic（/f??n?l?k/）compounds（酚類）,celluloseFig.3.2Thestructureofbranlayer2)StarchyEndosperm83%ofkernelNon-viable,butmayhaveenzymaticactivityContainshighlevelsofstarch75%ofwheatendospermsourceoffermentablesugarsContainsextensibleglutenproteins（可擴展的面筋蛋白）Verylittlemineral,fiber,fat&vitaminsFig.3.3ThestructureofstarchyendospermStarchGranulesinProteinMatrixFig.3.4Starchgraunlesinproteinmatrix3)Germ2-3%ofkernelViabletissueContainsembryo（/?embri??/）allrudimentary

(/?ru?d??mentri/

基本的）

growthtissuesResponsibleforgerminatione.g.duringmaltingofbarley（

/?bɑ?li/大麥）ContainshigherquantitiesoflipidthanotherfractionsFig.3.5Thestructureofgerm1.2小麥制粉工藝(Flourmillingprocess)Flourmillingisthecontinuousprocessthatisusedtotransformtherawwheatberry(小麥粒粉質(zhì)胚乳）intoaformwhichisofusetothebakingandotherindustries.1.2.1TheaimofwhiteflourmillingWhiteflouristheultimateproductofflourmilling.Theaimofwhiteflourmillingistoextractamaximumamountofendospermfromthewheatberry.白面粉是面粉加工的終極產(chǎn)物。碾磨白面粉的目的是從小麥漿果中提取最大量的胚乳。1.2.1TheaimofwhiteflourmillingTheouterbranlayersbecometheco-productoftheprocesscalledwheatfeed(麩皮粉).Manyoperationsalsoseparatetheembryonic（/?embri??n?k/胚

）partoftheberry,knownasthegerm.外層的麩皮層成為這個過程的副產(chǎn)品，稱為小麥飼料(麩皮粉)。許多操作也分離了漿果的胚胎部分，稱為胚芽。Thereisjustoneacceptedmannerinwhichflourisproducedglobally.Thisisknownasthegradualreductionsystem(逐步研細法).1.2.2TheflourmillingprocessTheflourmillingprocesscanberepresentedbyasimpleblockdiagram(Fig.3.7).Therearethreeprincipaldivisionswithintheprocess.Theseareknownasthebreakingsystem（研磨系統(tǒng)）,thepurificationsystem(/?pj??r?f??ke??n/清粉系統(tǒng)）

andthereductionsystem(粉碎系統(tǒng)）.Thepurificationsystemisnotfavouredbymanymillersandmaybeabsentfromprocesses.ItisoftenreplacedbywhatisknownastheSizingsystem（篩理系統(tǒng)）.Fig3.7Blockdiagramofmillingprocess.1.2.3面粉產(chǎn)品處理(1)殺蟲

面粉撞擊殺蟲機，可殺死面粉中各個蟲期的害蟲及蟲卵。(2)漂白、熟化

Ageingofwheatflourforbreadmakingisduetooxidation,eitherbystorageforsomeweeksaftermillingorbychemicalaction.Freshlymilledflourproducesaweakerandlessresilientdough,andhencealess‘bold’loaf,thanflourwhichhasbeenaged.

用于制作面包的小麥粉的老化是由于氧化，要么是由于碾磨后儲存了幾周，要么是由于化學(xué)作用。與老化過的面粉相比，新磨的面粉產(chǎn)生的面團更弱，彈性更差，因此也就不那么“膨脹”。1.2.4面粉產(chǎn)品處理小麥胚乳含有葉黃素、類胡蘿蘿卜素等黃色素，所以新制面粉顏色略黃。經(jīng)過2-3周儲藏后，由于緩慢的空氣氧化作用使色素破壞，面粉顏色變白，同時筋力也因氧化作用而有所增加，這就是面粉的自然熟化。面包用粉和多用粉拌入過氧化二苯甲酰粉劑，只起單純的漂白作用。(3)空氣分級小麥面粉是由大小不同的粉粒組成，小的lμm以下，大的超過200μm，最小的粉粒主要是蛋白質(zhì)碎片，含蛋白質(zhì)多，再大一些的粉粒主要是游離的淀粉粒，含蛋白質(zhì)少，更大的粉粒則是胚乳碎塊，保持著原有的淀粉粒鑲嵌在蛋白質(zhì)中的結(jié)構(gòu),蛋白質(zhì)含量與小麥胚乳相同。根據(jù)這一情況，即可得到高蛋白小麥粉(粉粒小于17μm)．低蛋白小麥粉(粉粒大小在17-40μm)一般蛋白質(zhì)含量的小麥粉(粉粒大于35或40μm)。1.2.5等級粉和專用粉生產(chǎn)工藝特點(1)等級粉（gradeflour）的生產(chǎn)同時生產(chǎn)兩種以上等級粉的制粉過程，稱為等級粉生產(chǎn)。按加工精度不同可分為特一粉、特二粉、標準粉、普通粉四類。(2)專用粉（tailoredflour）的生產(chǎn)我國目前面粉品種比較單一，國外的面粉品種就比較齊全，如面包粉、餅干粉、家庭用粉和其它用粉。專用粉與通用小麥粉之間的主要不同在于用途的針對性不同，對于各種粉的蛋白質(zhì)含量、水分、粒度、強度以及灰分等各方面的要求、也不相同?？梢酝ㄟ^小麥粉配制的方法生產(chǎn)專用粉，因此專用粉又稱配制粉。第二節(jié)面制食品的加工2.1面制食品的分類及特征面制食品是指以小麥面粉為主要原料制作的一大類食品。根據(jù)加工方式可分為焙烤食品和蒸煮食品2大類。面包餅干糕點焙烤食品掛面：普通掛面、風(fēng)味掛面、營養(yǎng)保健掛面方便面饅頭蒸包蒸煮食品以小麥粉為主要原料，經(jīng)過汽蒸或水煮方式熟制的一類食品。焙烤食品是指以谷物或谷物粉為基礎(chǔ)原料，加上油、糖、蛋、奶等一種或幾種輔助原料，采用焙烤工藝定型和成熟的一大類固態(tài)方便食品。

2.2面制食品的原輔料及其加工特性其它輔料主要原料食鹽面粉水酵母輔料糖油脂蛋及蛋制品乳及乳制品改良劑營養(yǎng)強化劑2.2.1面粉1面粉的化學(xué)組成(1)蛋白質(zhì)Protein8%-15%ofwheatflourisproteinHighproteinfloursfromhardwheatbestforbread,>11%Low-proteinfloursfromsoftwheat<9%forcakes,cookies（餅干）,pastries（糕點）Gliadin麥醇溶蛋白andglutenin麥谷蛋白themostimportantones,~85%Whenhydratedandmixed,formgluten,keycomponentofbreadRemainingglobulins麥球蛋白andalbumins麥清蛋白,-and-amylases面筋的主要成分是麥醇溶蛋白gliadins和麥谷蛋白glutenins.麥醇溶蛋白1條多肽鏈構(gòu)成，僅分子內(nèi)二硫鍵,較緊密的三維結(jié)構(gòu)，呈球形，多由非極性氨基酸組成。水合時具有良好的黏性和延伸性，缺乏彈性。麥谷蛋白17-20條多肽鏈構(gòu)成，呈纖維狀，既有分子內(nèi)二硫鍵，又有分子間二硫鍵，富有彈性但缺乏延伸性。Thegluteninfunctionisabletoformanextensivethree-dimensionalnetworkofmoleculesthroughdisulfidebonding,hydrogenbondingandhydrophobicinteractions.Allcontributetotheformationofacohesiveelasticdough.PropertyBehaviour/characteristicsSolubilityLowsolubilityinwaterandneutralbuffers.Productsareviscoelasticmaterials.Smallamountofmaterialsolublein70%(v/v)ethanol.MolecularstructureProteinchainscross-linkedbyintermolecular（分子間）disulfidebonds,andinsolublein70%(v/v)ethanol.Highmolecularweightandlowmolecularweightsubunitspresent.Regionsofα-helix,β-structureandrandomcoil（無規(guī)則線圈）structure.Amountinwheat30-45%oftotalprotein.AminoacidcontentHighinglutamine(≈30%)andproline(≈13%)Loweramountsofalltheotheraminoacids.Cysteinecontent≈2.4%(as1/2cystine).*

Glutenins,compositionandpropertiesPropertyBehaviour/characteristicsSolubilityExtremelylowsolubilityinwaterandneutralbuffers.Productsareofstickytexture.Dryproductsaremostlysolublein70%v/vethanol.MolecularstructureSinglepolypeptidechainscapableofsomeintramoleculardisulfidebonding.Considerableamountofα-helicalandrandomcoilstructure.Highincidenceofβ-turns.Molecularweight30000-50000Amountinwheat30-45%oftotalprotein.AminoacidcontentVeryhighinglutanine(≈35%).Prolinealsohigh(≈20%).Lowlevelsofarginine,lysineandhistidine.Lowlevelsofasparticacidandglutamicacid.Cysteinecontent≈3%(as?cystine).*Gliadins:compositionandpropertiesDoughFormationDoughsareviscoelastic(flowsandrecoils)Structurelargelyfromproteinscalledglutensconsistofgliadinsandglutenins30%ofaminoacidresiduesarehydrophobicwaterinsoluble;canbindwaterKneadingbreadsubjectsittoshearforcespromoteinteractionsbetweenglutenin

moleculesH-bonding,hydrophobicinteractions,S-Sbondscreateselasticproteinnetworks(films)whichtrapgasviscosityenhancedbygliadinsandstarchmolecules面團形成過程谷蛋白→先吸水膨脹→同時吸收醇溶蛋白、清蛋白、球蛋白→疏水基交聯(lián)，谷蛋白分子內(nèi)二硫鍵轉(zhuǎn)變?yōu)榉肿娱g二硫鍵→形成巨大的立體網(wǎng)絡(luò)結(jié)構(gòu)骨架→填充淀粉、脂肪、水、糖和無機鹽等→良好黏彈性和延伸性的面團。Initially,glutenisformedwhenflourandwateraremixedtogether.Theproteinsintheflour,gluteninandgliadincrosslink,usingthewaterasavehicletoformgluten.DoughFormationKneadtooptimumrheology

optimumdoughstrengthover-kneadingbreaksproteinstructurebeforekneadingafteroptimalkneading50mm1mm粗面筋面團在水中搓洗時，淀粉、可溶性蛋白質(zhì)、灰分等成分逐漸離開面團而懸浮于水中，最后剩下一塊具有黏彈性和延伸性的軟膠狀物質(zhì)，即粗面筋。Thewheatglutencomplexisaviscoelasticmixturecontainingaboutequalamountsofglutelins（谷蛋白）(gluteninsinthecaseofwheat)andprolamins(醇溶谷蛋白）,knownasgliadinsinthecaseofwheat.含水量60-70%，又稱濕面筋（wetgluten）。經(jīng)烘干，除水后為干面筋（vitaldrygluten)。Thismixture,asitseparatesfromthewashingofawheatflourdoughwithwaterordilutesaltsolution,containsabout33-35%solids.Itcanbedriedcarefully,e.g.flashdried(快速干燥）,toproducetheglutenofcommerce（商業(yè)）whichcanbereconstitutedinwatertogivearubbery（有彈力的）massoftexturesimilartotheundriedmaterial,andistermed`vital‘gluten（活面筋）.Itcontainsabout80%protein,10%starch,5%lipids,plusminerals,fibreandotherimpurities.面粉中蛋白質(zhì)的含量和質(zhì)量是影響加工最主要的因素。質(zhì)量包括兩方面：一是面筋蛋白占面粉總蛋白的比例。越高，黏彈性越好。二是麥谷蛋白和麥醇溶蛋白的相對含量。比例合適。谷蛋白過多，彈性和韌性太強，無法膨脹；醇溶蛋白過多，面團太軟弱，網(wǎng)絡(luò)不牢固。（2）carbohydrates75%ofthetotalweightLargelycomposeofstarchNativestarchgranuleinsolubleAmyloseandamylopectinwithinsphericalgranulesinrigid,semi-crystallinenetworkMillingcandamageasmallpercentage,increasewaterabsorptionandenzymeexposureSomeothercarbohydratesAsmallamountofsimplesugar,cellulose,fiber(~1%)損傷淀粉（damagedstarch）在小麥制粉過程中，由于磨的擠壓、研磨左右，有少量淀粉粒被破壞，這樣的淀粉稱為損傷淀粉。Someofthestarchgranulesareexposedtohighpressuresduringthemillingprocessandtheirsurfacesmaybebecomemechanicallyrupturedordamaged.Thesemi-crystallinestructureofthestarchgranulegivesitsimilarcharacteristicstoothersolidparticles,thusitcanbedamagedbymechanicaloperations.Theimportanceofdamagedstarchinthebreadmakingprocessisconsiderableandgenerallytwofold.Damagedstarchabsorbs2to4timesitsweightinwaterascomparedto0.4bynativestarch.Damagedstarchgranulesarealsosubjecttopreferentialattackbysomespecificenzymes(oneisβ-amylases).Someoftheseenzymesareincapableofattackinganintactnativestarchgranule.Starchdamageshouldbeoptimizedasithasbothpositiveandnegativeeffectsonbreadquality.Asmentioned,damagedstarchhasmuchgreaterwaterretentioncapacity;however,toomuchstarchdamageleadstostickydough,strongproofing,andundesirableredcrustcolor.(3)WheatlipidsLipidsaredistributedthroughoutthewheatkernelandrepresentcomponentsofmembranes,organelles(細胞器）andspherosomes(membrane-bounddroplets)（圓球體）intissuessuchasthealeuronelayers（糊粉層）,scutellum（角質(zhì)鱗片）andembryo.Intheendosperm,lipidsareassociatedwithproteinsmostlyasfullyacylatedglycerides,whilethoseassociatedwiththestarcharemonoacyllipids.Outsidethestarchtheycanexistastriglycerides,freefattyacidsandotherfreeforms.Althoughthelipidsarewidelydistributedinthekernel,theyareminorconstituentsinallbutthegerm.Lipidbilayers（雙分子層）formthebasisofbiomembranes,inwhichpolarlipids,particularlyphospholipids,areprominent.Inwheat,bilayersareabletoassociatewithproteinsandthesestructuresareinadynamicstate.(4)水分13.5±0.5%，過高，易酸敗變質(zhì)，游離水(5)礦物質(zhì)以灰分表示，越低，面粉精度越高。近年來，普遍采用粉色試驗代替灰分試驗。(6)維生素B族維生素，煙酸、泛酸和VE，VA含量很少，幾乎不含VC、VD常在面粉中添加一定量的維生素，以強化面粉的營養(yǎng)。（7）WheatenzymesTheenzymesinwheatareofsomeimportancetotheperformanceoftheflourinbreadmaking,especiallytheamylases.AmylasesTheamylaseareexamplesofhydrolasesastheycatalysethehydrolysisofthepolysaccharidesinthestarch.Oneofthemainenzymesofthistypeisα–amylase(EC3.2.1.1).Itisknownasanendo-hydrolase.Duringbreadmakingitreactsslowlywithdamagedstarchgranules,butrapidlywithgelatinisedstarchtoproduceamixtureofdextrins,otheroligosaccharidesandsmallamountsofmaltose.降落值（FallingNumber

）反應(yīng)淀粉酶含量和活性。淀粉酶能使淀粉液化，使黏度下降。以一定質(zhì)量的攪拌器在被酶液化的熱凝膠糊液中下降一段特定高度所需的時間來表示（S）。降落值↓表明糊黏度↓淀粉被酶解程度↑，酶活力↑作為面粉等級標準和專用粉重要指標。FN小于200，表示酶活性過強；200~300表示酶活性正常，大于300，則表示酶活性過低。

面粉的工藝性能

小麥面團品質(zhì)大多體現(xiàn)在小麥面團的流變學(xué)特性方面，小麥加工品質(zhì)好壞可以通過測定面團的流變學(xué)特性得到鑒定。MeasuringtherheologicalpropertiesofdoughBrabender?Farinograph?-E（1）粉質(zhì)圖指標吸水率（Waterabsorption）：指面團最大稠度處于500±20Bu時所需加水量。以占含水14%濕基面粉質(zhì)量的百分數(shù)表示，準確到0.1%。面粉的吸水率越高，則做面食時加水量越大，這樣不僅能提高單位重量面粉的出品率，而且能做出疏松、柔軟、存放時間較長的面食。

面團形成時間（Developmenttime）：從零點（開始加水）直至面團稠度達到最大時所需攪拌時間。一般軟麥面粉筋力差，形成時間短，在1~4min之間，適合做糕點、餅干等；硬麥面粉筋力強，形成時間在4min以上，可制作掛面、饅頭、面包等產(chǎn)品。美國面包粉的形成時間要求為（7.5±1.5）min。我國商品小麥的形成時間平均為2.3min。穩(wěn)定時間（Doughstability）：指面團粉質(zhì)曲線首次達到500Bu與離開500Bu所經(jīng)歷的時間。越長，穩(wěn)定性越好。最重要的指標。面團的穩(wěn)定時間越長，說明面團的加工穩(wěn)定性越好，面筋對剪切抵抗力越強，越適于制作面包；穩(wěn)定時間中等大小的面粉適于作饅頭、掛面；穩(wěn)定時間短的適宜做餅干、糕點。曲線的寬度反映面團的彈性，越寬彈性越大。

衰減度（Degreeofsoftening）：曲線最高點中心與達到最高點后12分鐘曲線中心兩者之差。表明在攪拌過程中的破壞速率，越高，面筋越弱。弱化度表明面團在攪拌過程中的破壞速率，也就是對機械攪拌的承受能力，也代表面筋的強度。該值越大，面筋越弱，形成的面團越易流變，面團不易加工。

評價值（valorimetervalue)：曲線從最高處開始下降起12分鐘后的評價計分。它是根據(jù)面團形成時間和面團弱化度給粉質(zhì)曲線圖一個綜合評分。一般認為強力粉的評價值在70以上，薄力粉在30以下，中力粉在30～70之間。(2)拉伸曲線將粉質(zhì)儀制備好的面團揉搓成粗短面條，將兩端固定，中間掛鉤向下拉，抗拉伸阻力以曲線的形式自動記錄下來，稱拉伸圖。TheExtensogramrecordedon-lineandrepresentedasacolordiagramonthemonitorshowstheexertedforceasafunctionofthestretchinglength(time).面團延伸性（Extensibility）（E）面團拉伸至斷裂時曲線的水平長度，以cm表示，是面團黏性、橫向延伸性的標志。抗拉伸阻力（Resistancetoextension）（R）在橫坐標50mm處的曲線高度，以Bu表示，是面團彈性、縱向彈性的標志。拉伸比（Rationumber）延伸性（cm）與拉伸阻力（Eu）的比值。用cm/Eu表示，反映抗拉伸強度。能量（Areabelowthecurve）(energy)指曲線所圍成的總面積，以cm2表示。亦代表面團強度。拉伸圖既反映面團強度和抗延伸阻力，又反映面團易流動性和延伸所需要的黏合力。2.2.2waterThepropertiesofthedoughwillvaryaccordingtothelevelofaddedwater.Toolittleandthedoughwillbefirmanddifficulttomould（制模）,producingbreadsthathavesmallvolumeandpoorexternalappearance.Toomuchandthedoughwillbesoftandalsodifficulttomould;itwillflowintheprover（醒發(fā)室）andgivepoor-qualitybread.The`optimum'levelofwaterisreallythemaximumquantitywecangetintothedoughandstillbeabletomouldthepiecesandgivebreadofacceptablequality.Hardnesswillaffectyeast-leavened（發(fā)酵）dough.Hardnessinwatercomesmainlyfromcalciumandmagnesiumbicarbonatesandsulfates.Therelativehardnessofwaterisexpressedindegreesofhardness,onedegreeofhardnessbeingtheequivalentof10ppmcalciumcarbonateinwater.Mediumsoftwater(50to100ppm)isconsideredtobethedesiredlevelofhardness.Softwater(0to15ppm)isundesirablebecauseittendstosoftentheglutenandproduceslack,stickydoughsandafinishedproductwithamoreopengrain.Butitissuitableforbiscuitsandnoodles.2.2.3YeastCulturesS.cerevisiae,orbakers’yeastPropertiesandcharacteristicsforbreadmakingGassingpowerFlavordevelopmentEthanolYeastproducesanalcoholicfermentation,whichisananaerobic(厭氧的）conversionofsugarsintocarbondioxidegasandethanol.Thesesugarsincludeboththosethataredirectlyfermentableaswellasthosethatareproducedastheresultofthehydrationofthestarchinflour.YeastculturesCommerciallyavailableYeastcream（酵母乳）Useddirectly,highlyperishable（容易腐爛的）Yeastcake（酵母餅）Yeastcreamthroughfiltrationpressorvac.filterRefrigerationrequired,shelflifeafewweekMetabolicallyactive,quickfermentationDryactiveyeast（活性干酵母）Homebreadmaking,smallbusinessoperationLast6monthsorlongerRequirehydration,notasactive2.2.4食鹽Abasicfunctionofsaltinbreaddoughistocontributeflavourbutitalsohasaninhibitingeffectontheformationofglutenduringmixing.2.2.5油脂在面制食品加工中，焙烤食品使用較多的油脂，常用的油脂有植物油、動物油、人造奶油和起酥油等。Compoundbakeryfats(mixturesofoilandsolidfatatagiventemperature)areusedtoimprovethegasretentionofdoughandtherebyincreasevolumeandsoftness;seeFig.Fig.Effectoffatadditiononbreadquality2.2.6糖與糖制品在面制食品加工中，糖是最重要的原料之一，尤其在焙烤食品中糖更是不可缺少的。面制食品中常用的糖制品有蔗糖、轉(zhuǎn)化糖漿、淀粉糖漿、蜂蜜等。Highlevelsofsugarinhibityeastactivityeventhoughitisfermentable.Inmodernbreadmakingsugarscontributetoproductsweetnessandcrustcolour.2.2.7蛋與蛋制品蛋品是生產(chǎn)面包、糕點及蒸包餡料的重要原料，尤其是在蛋糕和高檔面包中用量很大。蛋品中用量最多的是雞蛋、鴨蛋。蛋品的原料類型有帶殼鮮蛋、凍蛋、全蛋粉、蛋清粉等。2.2.8其他輔助料及添加劑為了有利于面制食品工藝操作和提高產(chǎn)品質(zhì)量，面制食品生產(chǎn)中使用的其他輔助料及添加劑有：乳化劑、氧化劑、疏松劑、增稠劑、抗氧化劑、香精香料和食用色素等。2.3.BreadProduce

面包的配方一般用百分比來表示，面粉的用量為100，其它配料占面粉用量的百分之幾。如甜面包配方為：面粉100白砂糖18水58酵母1.4食鹽0.8雞蛋12、奶粉5、復(fù)合改良劑0.5等。

2.3.1Ingredients2.3.2ModernBreadTechnologyThereareseveraldifferentmethodsofmakingbread.Straightdoughprocess（一次發(fā)酵法）

-Homemade,one-batch-at-a-time,notmuchbythebakingindustrySpongeanddoughprocessMostlyused,usingpartiallyconcentratedportionofdough-spongetoferment,andthenmixingwiththeremainingingredientsSpiralmixingandno-timedoughprocesses2.3.2.1straightdoughprocessFlourandrawingredients→mix→fermentation→divide（切塊）→ballmould（搓團）→rest（醒發(fā)）→mouldandtin（整形）→finalproof（最后醒發(fā)）→bake→cool→wrap（包裝）2.3.2.2Thespongeanddoughprocess(面包的二次發(fā)酵工藝）ThespongeanddoughprocessismostcommonintheUSA.Onlypartoftheingredientsarefermented-thesponge.GeneralflowchartWeighandmixingredientsdoughFermenteddoughPortionedandshapedbakeCoolslicepackfermentationfermentationThespongeanddoughprocess(面包的二次發(fā)酵工藝）Theadvantagesofthisprocessarebetterflavouredbread,betterkeepingqualityand,often,betterappearance.

Thespongeanddoughprocesscanbebrokendownintotwoparts:

First,a‘sponge’isformed.Secondisthe‘dough’stage.Theremainderoftheflour,sugarandwater,thefatormargarine(人造黃油）,saltand,sometimes,asmallamountofyeast,areaddedtothespongeandthoroughlymixedtogethertomakeasmooth,fairlystiffdough.

2.3.3Keyprocedures

2.3.3.1DoughmixingandprocessingInessence,mixingisthehomogenisationoftheingredients,whereaskneading（揉捏）isthedevelopmentofthedough(gluten)structure.However,bothprocessestakeplacewithinthesamemixingmachineandsocanbeconsideredasoneratherthantwoprocesses.Cell（穴窩）creationduringmixingTheproductionofadefinedcellularstructure（蜂窩結(jié)構(gòu)）inthebakedbreaddependsentirelyonthecreationofgasbubblesinthedoughduringmixingandtheirretentionduringsubsequentprocessing.Aftermixinghasbeencompletedtheonly`new‘gasavailableisthecarbondioxidegeneratedbytheyeastfermentation.Carbondioxidegashashighsolubilityrelativetoothergasesandinbreaddoughcannotformgasbubbles.Astheyeastproducescarbondioxide,thegasgoesintosolutionintheaqueousphasewithinthedoughuntilsaturationisachieved.Thereafter,continuedfermentationcausesdoughexpansionasthegasisretainedwithinitsstructure.2.3.3.2面團發(fā)酵面團發(fā)酵是面包生產(chǎn)的關(guān)鍵工序。發(fā)酵是面包獲得氣體、實現(xiàn)膨松、增大體積、改善風(fēng)味的基本手段。酵母的發(fā)酵作用是指利用糖(主要是葡萄糖)經(jīng)過復(fù)雜的生物化學(xué)反應(yīng)最終生成C02氣體的過程。發(fā)酵過程包括有氧呼吸和無氧呼吸。無氧呼吸有利，產(chǎn)生酒精，有醇香味。在面團發(fā)酵初期，酵母的有氧呼吸占優(yōu)勢，并迅速繁殖，產(chǎn)生很多新芽孢。隨著發(fā)酵的進行，無氧呼吸逐漸占優(yōu)勢。越到發(fā)酵后期，無氧呼吸越旺盛。

整個發(fā)酵過程中以無氧呼吸為主對面包的生產(chǎn)和質(zhì)量是有利的。

采用二次發(fā)酵工藝制作的面包質(zhì)量較好的原因:在于第一次發(fā)酵使酵母繁殖，面團中含有足夠的酵母數(shù)量增強發(fā)酵后勁，通過對一次發(fā)酵后面團的攪拌，一方面可使大氣泡變成小氣泡，另一方面可使面團的熱量散失，并使可發(fā)酵糖再次和酵母接觸，使酵母進行無氧呼吸。

2.3.3.3DoughprocessingThestagesrequiredtoprocessthebulkdoughintobreadmaybedescribedasfollows.1.Dividing2.Roundingandfirstmoulding3.Intermediateorfirstproving4.Finalmoulding1.DividingThebulkdoughisdividedtogeneratetheshapeandsizeofproductrequired.2.RoundingandfirstmouldingModificationoftheshapeofthedivideddoughpieceiscommon.Mechanicalmouldingsubjectsthedoughtostressesandstrainsandmayleadtodamagetotheexistinggasbubblestructurepresent.3IntermediateorfirstprovingAperiodofrestbetweentheworkcarriedoutbydividingandroundingandbeforefinalshapingmaybeused.Thelengthoftimechosenforthisprocessisrelatedtothedoughrheologyrequiredforfinalmoulding.Changesoccurindoughrheologyasitrests,thelongerthatitreststhegreaterwillbethechanges.Fig.4Effectoffirstproofonbreadquality.4FinalmouldingThebasicfunctionsofthisstagearetoshapethedoughtofittheproductconceptandtore-orientatethecellstructure.2.3.3.4ProvingandbakingProvingisthenamegiventothedoughrestingperiod,afterthemouldedpieceshavebeenputintotinsorplacedintrays,duringwhichfermentationcontinuesinacontrolledatmosphere,typically40-45℃and85%relativehumidity.Fig.CTX-rayimagesofdoughduringproof(notetheimageresolutionofthistechniqueonlyrevealsbubblesofabout1mmorlarger).Yeastfeedsonthesugarstoproducecarbondioxideandalcohol.Thecarbondioxidediffusesintothegasbubblesinthedough,causingthemtogrowandthedoughtoexpand.Progressivelythesizeofthegasbubblesincreases.bakingAfterproofthedoughmustbeheat-set,thatisbaked.Bakingtemperatureswillvaryfromoventoovenandwithproduct.Typicallyoventemperatureslieintheregionof180-220℃,15-50min.Gelatinizationofthestarchstartsatabout60℃andinitiallythestarchgranulesabsorbanyfreewaterinthedough.Alpha-amylaseactivityconvertsthestarchintodextrinsandthensugars.Aswaterisdrivenoffandthecrustacquiresitscharacteristiccrispnessandcolour,flavourandaromadevelopfromtheMaillardreactions,whichstartattemperaturesabove115℃.2.4餅干(Biscuits)的生產(chǎn)GB/T20980-2007是以小麥粉（可添加糯米粉、淀粉等）為主要原料，加入（或不加入）糖、油脂及其他原料，經(jīng)調(diào)粉（或調(diào)漿）、成型、烘烤（或煎烤）等工藝制成的口感酥松或松脆的食品。2.4.1分類按加工工藝分為13類1.塑性餅干shortbiscuit2.韌性餅干semihardbiscuit3.發(fā)酵餅干fermentedbiscuit4.壓縮餅干compressedbiscuit5.曲奇餅干cookie2.4.1分類6.夾心餅干sandwichedbiscuit7.威化餅干wafer8.蛋圓餅干macaroon9.蛋卷eggroll10.煎餅crispfilm11.裝飾餅干decorationbiscuit12.水泡餅干spongebiscuit2.4.2BISCUITPRODUCTIONPROCESSES與面包相比，餅干在原輔料上的異同點：相同點二者在原輔料的種類上相同的方面是，面粉、糖、蛋品相異點①使用的添加劑不同，餅干需添加疏松劑、抗氧化劑

I)疏松劑：NaHCO3、NH4HCO3（食用級）、酵母對于酥性、甜酥性、韌性餅干來說，不需發(fā)酵；對于蘇打餅干來說，則要發(fā)酵。II)抗氧化劑：因餅干的用油量大，所以需添加抗氧化劑

有BHA（丁基羥基茴香醚）BHT（丁基羥基甲苯）其用量為0.002~0.004%②面粉質(zhì)量要求不同一般餅干的生產(chǎn)（粗、韌、酥、甜酥）：含面筋質(zhì)量低（20~26%）、蛋白質(zhì)8~10%，面團的彈性中等或較差，延伸性較大。發(fā)酵餅干（蘇打餅干）：濕面筋的含量高（30%左右），蛋白質(zhì)13~14%，面團的彈性及延伸性要求中等或較好。③生產(chǎn)的工藝有差異一般的餅干不需發(fā)酵；蘇打餅干需發(fā)酵。④油脂用量多以人造奶油、起酥油為好。

⑤酥性面團shortpastrydough與韌性面團elasticdough之分酥性面團——和面時未使面筋充分形成的面團，面團結(jié)構(gòu)松散韌性面團——使面筋充分形成的面團，韌性、彈性較好⑥香精、香料、色素多2.4.2餅干的生產(chǎn)工藝流程餅干生產(chǎn)的基本工藝為：原輔料預(yù)處理→面團調(diào)制→輥軋→成型→焙烤→噴油一冷卻一包裝。面團調(diào)制是將生產(chǎn)餅干的各種原輔料混合成具有某種特性面團的過程。餅干生產(chǎn)中面團調(diào)制是最關(guān)鍵的一道工序。餅干面團調(diào)制過程中，面筋蛋白并沒有完全形成面筋，不同的餅干品種，面筋形成量是不同的，阻止面筋形成的措施也不一樣。酥性面團的調(diào)制

酥性面團是用來生產(chǎn)酥性餅干和甜酥餅干的面團。要求面團有較大的可塑性和有限的黏彈性，面團不粘軋輥和模具，餅干坯應(yīng)有較好的花紋，焙烤時有一定的脹發(fā)率而又不收縮變形。要達到以上要求，必須嚴格控制面