Abstract: The impact of adding polysaccharides extracted from liquid-cultured mycelia of Inonotus obliquus into yak yogurt on its sensory evaluation score and titratable acidity was investigated to determine the optimal addition amount of the polysaccharides. The process parameters for producing yak yogurt with added Inonotus obliquus polysaccharides were optimized, and the quality of the yogurt prepared under optimized conditions was evaluated and compared with that of yogurt without added Inonotus obliquus polysaccharides as a control. The results showed that addition of 0.4% Inonotus obliquus polysaccharides to yak yogurt led to the highest sensory score together with a moderate acidity. Using orthogonal array design, the optimal process conditions were determined as follows: ratio of Streptococcus thermophilus G2 to Lactobacillus paracasei L9, 1:1; fermentation time, 14 h; temperature, 38 ℃; and sucrose concentration, 8 g/100 mL. Compared with the control, the as-prepared yogurt increased the number of viable lactic acid bacteria, titratable acidity and water-holding capacity by 34.1%, 11.0% and 16.8% respectively, and the pH value decreased accordingly. Addition of Inonotus obliquus polysaccharides into yak yogurt improved its firmness and viscosity as well as flavor.

Key words: Inonotus obliquus polysaccharides, yak yogurt, sensory evaluation, flavor, quality

摘要： 通过液体深层发酵技术生产桦褐孔菌并提取其多糖，以感官评分与滴定酸度为依据，通过单因素试验确定最佳多糖添加量，进一步优化桦褐孔菌多糖牦牛酸乳的生产工艺参数，在最优工艺参数条件下研究桦褐孔菌多糖添加对牦牛酸乳品质的影响。结果表明：桦褐孔菌多糖添加量为0.4%时，牦牛酸乳的感官评分最高且酸度较为适口；采用正交试验优化牦牛酸乳的生产条件，获得最佳生产工艺为嗜热链球菌G2与副干酪乳杆菌L9发酵剂复配比1∶1、发酵时间14 h、发酵温度38 ℃、蔗糖添加量8 g/100 mL，该条件下，添加桦褐孔菌多糖的牦牛酸乳中乳

关键词: 桦褐孔菌多糖, 牦牛酸乳, 感官评价, 风味, 品质