藜麦酸奶混菌发酵工艺优化及品质与风味评价

本研究以膨化藜麦粉、牛奶为原料，选取嗜热链球菌6063、保加利亚乳杆菌6064、动物双歧杆菌B15混合发酵藜麦牛奶，在单因素实验基础上采用正交试验对发酵工艺进行优化，并探究膨化藜麦粉的添加对酸奶品质及风味的影响。结果表明，三种益生菌发酵藜麦酸奶的最佳菌种配比为嗜热链球菌:保加利亚乳杆菌:动物双歧杆菌=2:1:2，最佳工艺为接菌量2%（v/v），藜麦添加量5%（w/v），发酵温度41 ℃。在此条件下，藜麦酸奶风味良好，乳酸菌总活菌数达到109 CFU/mL。从发酵开始至贮藏21 d结束，藜麦酸奶可滴定酸度始终高于纯酸奶，乳酸菌总活菌数低于纯酸奶。藜麦酸奶成品的蛋白质、多酚及黄酮含量分别比纯酸奶提高了88.67%、166.67%、284.62%。乳酸、甲酸、乙酸、丙酮酸含量分别为5.80、1.42、0.11、0.01 mg/g。利用气相色谱-质谱联用仪（GC-MS）进行风味分析，藜麦酸奶中共检出74种挥发性风味物质，与纯酸奶相比，新产生30种挥发性风味物质。研究结果将为藜麦酸奶新产品的开发提供工艺依据，进一步促进藜麦的应用与开发。

Optimization of Fermentation Process and Evaluation of Quality and Flavor of Quinoa Yogurt Produced by Mixed Lactic Acid Bacteria

In this study, Streptococcus thermophilus 6063, Lactobacillus bulgaricus 6064 and Bifidobacterium animalis B15 were selected to ferment quinoa yogurt, and the puffed quinoa powder and milk were used as raw materials. Fermentation process was optimized by orthogonal experiment on the basis of single-factor experiments. And the effects of puffed quinoa powder on quality and flavor of yogurt were also evaluated. Results indicated that the optimal fermentation conditions were as follows: Streptococcus thermophilus: Lactobacillus bulgaricus: Bifidobacterium animalis=2:1:2, inoculation amount 2%(v/v), quinoa powder 5%(w/v) and fermentation temperature 41 ℃. Under these conditions, quinoa yogurt had good flavor, and the total viable number of lactic acid bacteria reached 109 CFU/mL. From the beginning of fermentation to the end of storage for 21 days, the titratable acidity of quinoa yogurt was always higher than that of plain yogurt, but the total number of viable lactic acid bacteria was opposite trend. Compared with plain yogurt, the contents of protein, polyphenols and flavonoids in quinoa yogurt increased respectively by 88.67%, 166.67%, and 284.62%. The contents of lactic acid, formic acid, acetic acid and pyruvate in quinoa yogurt were 5.80, 1.42, 0.11 and 0.01 mg/g, respectively. 74 kinds of volatile substances were detected in quinoa yogurt by GC-MS. Compared with pure yogurt, 30 kinds of new volatile substances were discovered. The research results would provide a technology support for further research and new product development of quinoa yogurt, promoting the application and development of quinoa.