嗜热链球菌的筛选及酸奶发酵剂的复配优化

Screening of Streptococcus thermophilus and optimization of mixture of yogurt starter

酸奶发酵剂的好坏决定了酸奶的品质。为研制出具有优良发酵特性的酸奶发酵剂,测试了50株嗜热链球菌的产酸与产黏能力,筛得1株快速产酸菌株NG024和2株高产黏菌株NG026和NG067。根据发酵乳特性得到嗜热链球菌的最佳复配范围,后加入保加利亚乳杆菌BG003继续优化,得到最佳酸奶发酵剂复配方案(NG024、NG067和BG003的体积比为1∶4∶0.0001)。此复配方案的发酵乳在感官评价上各单项得分与总分均最高,均优于竞品发酵剂Yo-mix883和YF-L822,流变学特性与竞品相似,可为酸奶发酵剂开发与利用提供理论依据。

The yogurt starter is the most important factor in controlling the overall quality of yogurt.Herein,we tested 50 strains of Streptococcus thermophilus with regards to their production ability of acid and exopolysaccharides(EPS),leading to 1 strain(NG024)with rapid acid production 2 strains(NG026 and NG067)with high yield of EPS.The optimal mixture ranges of Streptococcus thermophilus strains were selected based on the characteristics of fermented milk,then Lactobacillus bulgaricus BG003 was added for further optimization.As a result,the optimal mixture formula of yogurt starter culture(V(NG024)∶V(NG067)∶V(BG003)=1∶4∶0.0001)provided the highest single score and total score in sensory evaluation,and such fermented milk proved to be better than two commercial yogurt starter cultures(Yo-mix883 and YF-L822).Our research could provide theoretical basis for the development and utilization of yogurt starter culture.