豆漿粉即以脫脂大豆為原料,經加水浸提、過濾、濃縮、噴霧等工序加工成的豆粉。生產豆漿粉宜選用氮溶指數(NSI)高的低變性豆粕為原料。
(一)脫脂大豆的加工
脫tuo脂zhi大da豆dou是shi提ti取qu油you脂zhi後hou的de殘can餘yu物wu。因yin提ti取qu油you脂zhi的de方fang法fa不bu同tong有you豆dou粕po和he豆dou餅bing之zhi分fen,豆dou粕po是shi指zhi用yong溶rong液ye浸jin出chu法fa提ti取qu油you脂zhi後hou的de殘can餘yu物wu,而er豆dou餅bing則ze是shi指zhi用yong壓ya榨zha法fa提ti取qu油you脂zhi後hou的de殘can餘yu物wu。
zaituozhidadoushengchanguochengzhong,youyushouduozhongyinsudeyingxiang,huidaozhidadoudanbaifashengbutongchengdudebianxing,yinci,yongbutongfangfasuojiagongdetuozhidadoudexingzhuangyousuochayi。zaituozhiguochengzhong,daozhidanbaizhibianxingdezhuyaoyuanyinyou:受熱程度、溶劑種類及大豆所處的狀態等。如用正己烷這樣的疏水性低沸點有機溶劑,且在整個加工過程中注意溫度不超過60℃,則蛋白質不會變性,而用酒精這樣的親水性溶劑則易使蛋白質變性。
1.壓榨法製取脫脂大豆
壓ya榨zha法fa是shi通tong過guo對dui大da豆dou加jia壓ya提ti取qu油you脂zhi來lai獲huo得de脫tuo脂zhi大da豆dou的de。又you因yin壓ya榨zha前qian大da豆dou處chu理li溫wen度du的de不bu同tong可ke分fen為wei冷leng榨zha法fa和he熱re榨zha法fa。冷leng榨zha法fa是shi采cai用yong軟ruan化hua處chu理li的de大da豆dou,不bu經jing加jia熱re,直zhi接jie加jia壓ya壓ya榨zha提ti取qu油you脂zhi,獲huo得de脫tuo脂zhi大da豆dou的de方fang法fa。由you於yu在zai壓ya榨zha前qian未wei進jin行xing加jia熱re,蛋dan白bai質zhi變bian性xing小xiao,使shi脫tuo脂zhi大da豆dou中zhong可ke溶rong性xing蛋dan白bai質zhi保bao持chi率lv能neng達da到dao80%~90%,但冷榨法所得脫脂大豆中脂肪含量較高(5%~10%),因而在貯藏中易引起油脂的氧化酸敗。
為了提高出油率,人們往往先把大豆預熱壓扁,在壓榨過程中,再用蒸汽加熱,以降低油的粘度,使其容易流出。如大豆在榨油前經125℃左右的溫度熱炒,榨油時,在137.2~166.6兆帕的壓力下,保持1~3分鍾,受熱在130℃以(yi)上(shang),故(gu)稱(cheng)其(qi)為(wei)熱(re)榨(zha)法(fa)。用(yong)熱(re)榨(zha)法(fa)獲(huo)得(de)的(de)脫(tuo)脂(zhi)大(da)豆(dou)脂(zhi)肪(fang)含(han)量(liang)低(di),水(shui)分(fen)較(jiao)少(shao),易(yi)粉(fen)碎(sui),但(dan)大(da)豆(dou)蛋(dan)白(bai)發(fa)生(sheng)了(le)相(xiang)當(dang)大(da)的(de)熱(re)變(bian)性(xing),水(shui)溶(rong)性(xing)蛋(dan)白(bai)質(zhi)的(de)比(bi)率(lv)(對全蛋白)在30%以下,故熱榨脫脂大豆宜作為脫脂豆粉加工的原料。
2.溶劑浸出法製取脫脂大豆
溶劑浸出法是將大豆經適當的熱處理(溫度低於lOO℃)、yabian,zaiyongyoujirongjitiquyouzhi,huodetuozhidadoudefangfa。yongcifangfahuodedetuozhidadouchengkelizhuang,danbaizhihanlianggao,zhifanghanliangdi,shuifenyedi,youyiyufensui。qidanbaizhibianxingchengduzhuyaoyinrongjidezhongleijituozhidadouyurongjifenlidefangfabutongeryi。
一(yi)般(ban)來(lai)說(shuo),以(yi)石(shi)油(you)係(xi)溶(rong)劑(ji)為(wei)主(zhu)的(de)疏(shu)水(shui)性(xing)很(hen)強(qiang)的(de)溶(rong)劑(ji),使(shi)脫(tuo)脂(zhi)大(da)豆(dou)蛋(dan)白(bai)質(zhi)變(bian)性(xing)的(de)力(li)量(liang)非(fei)常(chang)弱(ruo),即(ji)使(shi)用(yong)較(jiao)高(gao)溫(wen)度(du)處(chu)理(li),蛋(dan)白(bai)質(zhi)也(ye)幾(ji)乎(hu)不(bu)變(bian)性(xing)。與(yu)此(ci)相(xiang)比(bi),酒(jiu)精(jing)等(deng)親(qin)水(shui)性(xing)強(qiang)的(de)有(you)機(ji)溶(rong)劑(ji),則(ze)使(shi)蛋(dan)白(bai)質(zhi)變(bian)性(xing)的(de)力(li)量(liang)很(hen)強(qiang)。因(yin)此(ci),通(tong)常(chang)製(zhi)取(qu)脫(tuo)脂(zhi)大(da)豆(dou)用(yong)的(de)溶(rong)劑(ji)是(shi)疏(shu)水(shui)性(xing)很(hen)強(qiang)的(de)正(zheng)己(ji)烷(wan)。以(yi)前(qian)使(shi)用(yong)石(shi)油(you)醚(mi),石(shi)油(you)醚(mi)並(bing)非(fei)單(dan)一(yi)組(zu)分(fen)物(wu)質(zhi),其(qi)中(zhong)含(han)有(you)高(gao)沸(fei)點(dian)成(cheng)分(fen),所(suo)以(yi)除(chu)掉(diao)溶(rong)劑(ji)要(yao)用(yong)過(guo)熱(re)蒸(zheng)汽(qi),因(yin)此(ci),製(zhi)成(cheng)的(de)脫(tuo)脂(zhi)大(da)豆(dou)的(de)蛋(dan)白(bai)質(zhi)變(bian)性(xing)程(cheng)度(du)很(hen)高(gao),它(ta)隻(zhi)宜(yi)用(yong)作(zuo)製(zhi)備(bei)醬(jiang)油(you)和(he)味(wei)精(jing)的(de)原(yuan)料(liao),而(er)不(bu)宜(yi)用(yong)來(lai)生(sheng)產(chan)脫(tuo)脂(zhi)豆(dou)粉(fen)。
shituozhidadouyurongjifenlidefangfazhuyaoqujueyurongjidexingzhi,jiqinshuixingdaxiaohefeidiangaodi,yijirongjijinchudefangfa。rushangsuoshu,caiyongqinshuixingxiaodeshushuixing、低沸點有機溶劑時,因在低溫條件下便可使脫脂大豆與溶劑分離,故使蛋白質的變性小,反之,蛋白質的變性較強。
rongjijinchufakefenweijianxieshihelianxushiliangzhong,jianxieshiyouyutuozhidadouherongjifenlicaiyongzhengqizhijiejiechudexingshi,suoyishidanbaizhibianxingdechengdugao。erlianxushishitongguojianyahuozhejianjiejiarerongjihezhengqijiaredengbanfatuochurongji,gukeshengchanchudibianxingtuozhidadou。zongzhi,jiangchangguidegaowenchulituoronggaiweidiwenchulituorong,biankekongzhidanbaizhidebianxing。ruweileshixiandanbaizhidedibianxing,kecaiyongzhenkongdiwenhuoshunjiangaowentuorongdengjishucuoshi,yiquebaojiarewendubuchaoguo80℃;直接蒸汽脫溶(脫臭)的時間不超過15分鍾。例如,采用“閃蒸脫溶”、“真空脫溶”工藝,可使可溶性大豆蛋白的保持率在92%以上,變性率在2%~3%以下。
(二)豆漿粉加工工藝要點
1.浸泡
將(jiang)氮(dan)溶(rong)指(zhi)數(shu)高(gao)的(de)脫(tuo)脂(zhi)大(da)豆(dou)用(yong)水(shui)充(chong)分(fen)浸(jin)泡(pao),浸(jin)出(chu)其(qi)中(zhong)所(suo)含(han)的(de)可(ke)溶(rong)性(xing)成(cheng)分(fen)。浸(jin)泡(pao)時(shi)應(ying)注(zhu)意(yi)用(yong)水(shui)量(liang)和(he)水(shui)溫(wen)。用(yong)水(shui)量(liang)過(guo)大(da),雖(sui)可(ke)浸(jin)出(chu)較(jiao)多(duo)的(de)可(ke)溶(rong)性(xing)成(cheng)分(fen),但(dan)會(hui)造(zao)成(cheng)後(hou)續(xu)濃(nong)縮(suo)工(gong)序(xu)的(de)時(shi)間(jian)延(yan)長(chang),增(zeng)加(jia)費(fei)用(yong)。比(bi)較(jiao)適(shi)宜(yi)的(de)用(yong)水(shui)量(liang)為(wei)原(yuan)料(liao)脫(tuo)脂(zhi)大(da)豆(dou)的(de)10倍bei左zuo右you。浸jin泡pao過guo程cheng以yi在zai稍shao稍shao加jia溫wen條tiao件jian下xia進jin行xing較jiao為wei適shi宜yi。這zhe不bu僅jin會hui使shi以yi後hou的de處chu理li較jiao易yi進jin行xing,而er且qie可ke以yi降jiang低di製zhi品pin的de生sheng物wu活huo性xing,使shi製zhi品pin趨qu於yu穩wen定ding。
2.過濾
浸泡結束後,用離心機對浸泡物係進行過濾,去除不溶物,獲得濾液。
3.濃縮
將離心過濾所得的濾液進行減壓濃縮,提高濾液的濃度,以利於噴霧幹燥。但一般需濃縮至幹物質含量接近15%即可,不宜過度,否則濃縮物粘度過大,甚至凝固,使噴霧幹燥難以進行。
4.噴霧幹燥
將濃縮液在壓力噴霧幹燥機中進行幹燥,使其成為含水量為2%~3%的豆漿粉。在噴霧幹燥時,應將幹燥機的進風溫度控製在180℃,出風溫度控製在90℃。幹燥溫度控製不當,會造成蛋白質因過度受熱變性,導致成品溶解度降低。
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