影响酸豆乳质量因素的研究

Study on Affecting Factors of the Quality of Soy based Yoghurt

利用分离训化的保加利亚乳酸杆菌ＹＬｂ－５和嗜热链球菌Ｓｔ－２对豆乳进行发酵试验。结果表明，豆乳的风味、组织状态和菌种特性以及发酵条件均影响酸豆乳的质量。ＹＬｂ－５菌和Ｓｔ－２菌在纯豆乳中虽生长产酸，但其酸度均低于发酵牛乳的酸度。ＹＬｂ－５菌在纯豆乳中生长弱，且使发酵豆乳凝固不良。添加产酸促进剂可提高酸豆乳的酸度。固形物含量为７％的脱腥豆乳，经１００℃处理１５～２０ｍｉｎ，以４％接种量接入ＹＬｂ－５菌和Ｓｔ－２菌（比例为１∶１），于４３℃发酵４ｈ，再经４℃后熟２４ｈ，可得到色泽洁白；组织细腻；凝乳良好；少量乳清析出；酸甜爽口的酸豆乳。

The fermentation test of soy yoghurt using Lactobacillus bulgaricus YLb-5 and Streptococcus thermophilus St-2 was done.The results showed that the quality of soy yoghurt was affected by the flavour and texture of soy milk,the characteristic of lactic acid bacteria and fermentation conditions of soy yoghurt.Although YLb-5 strains and St-2 strains grew and produced acid in pure soy milk,the acidity produced in soy milk was lower equally than the cow milk.YLb-5 strains showed weak growth in soy milk,and the soy yoghurt coagulated unthorough.Adding growth promoting agent in soy milk increased the acidity of soy yoghurt.The optimum conditions of soy yoghurt fermentation were:the solid contents of deodorized soy milk was 7%,the soy milk was sterilized(100℃ for 15-20min) and fermented with 4% mixed starter culture(the proportion of YLb-5 and St-2 was 1∶1),4h of culturing at 43℃,then to make it placed at 4℃ for 24h.