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酸豆奶稳定性研究及配方设计

Studies on Stability and Formula Design of the Fermented Soy-milk

【作者】 陈璐

【导师】 张铁华;

【作者基本信息】 吉林大学 , 食品工程, 2013, 硕士

【摘要】 酸豆奶是以纯豆浆为原料,使用乳酸菌发酵生产的一种酸凝乳食品。而要想获得可接受程度好的酸豆奶,就必须解决现阶段酸豆奶存在的稳定性问题和风味问题。解决方法一是选用良好的发酵菌种,以期其能够在纯豆乳中良好地生长,产酸产粘性能良好,凝乳状态稳定,并可以分解不良物质且产生发酵乳的风味物质;二是在纯豆乳原料中添加一定的稳定剂和碳源,以提高菌种的发酵性能,增强体系的稳定性。本文选用含保加利亚杆菌、嗜热链球菌、嗜酸乳杆菌、干酪乳杆菌、双歧杆菌五种菌的双歧杆菌酸奶发酵剂(后称五株菌),添加改性的乳清蛋白来代替一般的稳定剂,并加入蔗糖来补充豆乳中供乳酸菌生长利用碳源的不足,获得具有良好益生作用、凝乳状态良好、风味怡人的凝固型纯豆酸豆奶。主要研究成果如下:将菌种其接种于不同体积分数的豆乳驯化培养基上不断分级驯化后,传代驯化并扩培,获得酸豆奶发酵菌种。此菌种接种于纯豆乳体系中,凝乳时间由6.5±0.02h缩短至4±0.02h,酸度由50.0±0.3~0T提高到了55.6±0.3~0T,乳酸菌总菌数由驯化前的(1.05±0.07)×10~7cfu/mL增加到(1.89±0.06)×10~7cfu/mL,粘度达到1925.6±3.8厘泊。并且观察最终的凝乳状态,发现其凝乳结构坚实,表面光滑细腻,无乳清析出,该菌种具备稳定的发酵性能。纯豆乳中添加不同量的聚合乳清分离蛋白(Polymerized whey protein isolate,PWPI)和改性浓缩乳清蛋白(Polymerized whey protein concentrate, PWPC)来改善酸豆奶的凝乳稳定性,通过考察凝乳时pH值、酸度、粘度、硬度、干物质含量这些指标,选择3%PWPI和7%PWPC两个水平进行了下一步试验,添加不同种类及添加量的糖类,最终确定添加7%PWPC、6%蔗糖,这种条件下发酵的酸豆奶pH值4.52±0.01,酸度68±10T,干物质含量达到了12.36±0.04%,粘度和硬度适中,凝乳状态稳定,口感细滑,组织柔软。使用三种不同的菌种进行发酵对比,并对不同配方的酸豆奶的粘度、硬度、持水力进行比较,最终确定,酸豆奶的配方为添加6%白砂糖,0.02%乳化剂,加入改性浓缩乳清蛋白溶液7%,双歧杆菌酸奶发酵剂(五株菌)接种量3%,43℃发酵至凝乳,4℃冷藏后熟,可得到凝乳状态稳定、口感风味良好的酸豆奶。通过进行28天的贮藏实验,证明了经过本实验方法获得的酸豆奶在保质期内凝乳状态稳定,菌种的发酵性能下降缓慢。到28d时,pH值为4.28±0.02,在可接受范围内;乳酸菌总菌数为(9.7±1.5)×10~6cfu/mL,符合国际乳品联合会(IDF)对发酵乳制品中含活菌数要求;持水力为95.13±0.25%,有少量的乳清析出,证明本产品保质期可达到28d。并且发现双歧杆菌在整个贮藏期内,活菌数基本不变,保持在一定的稳定状态,而干酪乳杆菌活菌数在贮藏前两周也可达到107cfu/mL,因此能够说明,产品在保质期内,可以保证很好的益生保健作用。使用本实验的配方及发酵方法,可获得pH为4.5~4.6,酸度为65~70~0T,乳酸菌总菌数能够达到(1.09±0.02)×10~8cfu/mL,具有大豆正常色泽、淡淡豆香及发酵制品芳香,口感细滑,柔软粘稠,酸甜度适宜、凝乳组织均匀稳定的酸豆奶。对产品的营养成分进行分析,其各项指标均达到营养参考值,并且发现蛋白含量达到3.69g/100g,相比一般的酸牛乳蛋白含量2.8g/100g高很多,表明其具有更高的营养价值。

【Abstract】 Fermented soy-milk is a kind of curdy food fermented by lactic acid bacteriapure soybean milk. The stability problems and flavour issues of current fermentedsoy-milk must be solved with the methods that using the fermented cultures whichhave good fermenting property in pure soybean milk and adding stabilizer and carbonsource to soybean raw material. A starter culture consists Lactobacillus bulgaricus,Streptocus thermophilus, Lactobacillus acidophilus, Lactobacillus casei,Bifidobacterium was chosen to ferment, while polymerized whey protein andsaccharides were added, so that we get the fermented soy-milk with good texture,nice flavor and health-promoting effects. The research results are as follows:The fermented culture after the domestication on the soybean milk culturemedium of different concentrations was used to ferment, so as the time of gelation offermented soy-milk was shortened from6.5±0.02h to4±0.02h, Acidity of it raisedfrom50.0±0.3~0T to55.6±0.3~0T, The total number of lactic acid bacteria of it raisedfrom (1.05±0.07)×10~7cfu/mL to (1.89±0.06)×10~7cfu/mL, viscosity was up to1925.6. This fermented culture has stable fermentation performance.Compared the samples that added the different additive amount of polymerizedwhey protein and saccharides based on pH value, acidity, viscosity, rigidity, amount ofdry matter, the sample fermented by the formula that7%PWPC,6%sugar can get theresult that pH is4.52±0.01, acidity is68±1~0T, amount of dry matter is up to12.36±0.04%, while having good sensory characteristics.According to the comparison and analysis on samples fermented by differentstarter cultures and different formula, the fermented soy-milk fermented by the way that adding7%PWPC,6%sugar,0.02%emulsifier,3%starter culture, fermenting at43℃have good texture and flavor.The result indicated that the product had good quality with its viable cellnumbers, pH value and acidity being of (1.09±0.02)×10~8cfu/mL,4.5~4.6and65~700T, respectively. After the storage at4℃for28d, the viable number of theproduct was still (9.7±1.5)×10~6cfu/mL and the pH value and water-holding capacityof it decreased to4.28±0.02and95.13±0.25%. During the storage period, the viablenumber of bifidobacterium kept stable practically, proved that the fermented soy-milkhas good heslth-holding effect in the storage period.The nutrition ingredient of product was analyzed, each index all reached nutrientreference value, and the protein content is3.69g/100g, compared with commonyogurt with protein content being2.8g/100g, shows that it has a higher nutritionalvalue.

【关键词】 酸豆奶发酵稳定性乳清蛋白
【Key words】 fermented soy-milkfermentationstabilitywhey protein
  • 【网络出版投稿人】 吉林大学
  • 【网络出版年期】2013年 S2期
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