Abstract: The optimal parameters for ultrasonic-assisted enzymatic extraction of polysaccharides from Potentilla anserina L. using a mixture of cellulase, pectinase and papain (2:1:0.5) were determined as follows: enzyme dosage 49 U/g, ultrasonic time 100 min and pH 4.4. Under these conditions, the maximum yield of polysaccharide extract from Potentilla anserina L. (PAPE) of (6.89 ± 0.08)% was obtained. Furthermore, the effect of PAPE on yak yoghurt fermentation was investigated. The results showed that PAPE could significantly enhance the viable count and acid-producing capacity of Streptococcus thermophilus CICC 6038, Lactobacillus bulgaricus CICC 20247 and Lactobacillus fermentum HY01 in a dose-dependent manner. Yoghurt added with PAPE at 2 g/100 mL concentration had a hardness of (163.0 ± 9.9) g, a viscosity of (?182.9 ± 1.6) g·s, a consistency of (69.7 ± 1.7) g·s, a cohesiveness of (410.0 ± 6.0) g and it had a good taste, with a sensory score of 7.78; its antioxidant capacity in terms of scavenging capacity against hydroxyl, superoxide anion and 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) cation radicals increased significantly compared with the control group. This study provides new ideas for improving the quality and added value of yak yogurt.

Key words: Potentilla anserina L. polysaccharide extract; yak yoghurt; fermentation; antioxidant

摘要： 采用超声辅助酶法从植物蕨麻中提取多糖，优化所得工艺参数为：复合酶（纤维素酶、果胶酶、木瓜蛋白酶质量比2∶1∶0.5）添加量49 U/g、超声时间100 min、酶解pH 4.4，此时蕨麻多糖提取物（Potentilla anserina L. polysaccharide extract，PAPE）提取率高达（6.89±0.08）%；进一步探究PAPE对牦牛酸乳发酵的影响，结果表明，PAPE可显著提升嗜热链球菌CICC 6038、保加利亚乳杆菌CICC 20247及发酵乳杆菌HY01的活菌数及产酸能力，且呈现剂量依赖性。当PAPE添加量为2 g/100 mL时，牦牛酸乳硬度达到（163.0±9.9）g，黏度为（－182.9±1.6）g·s，稠度为（69.7±1.7）g·s，内聚力为（410.0±6.0）g，且具有较好的口感，感官评分为7.78；其抗氧化能力也显著上升，具体表现为对羟自由基、O2－·及2,2’-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基的清除率较对照组均增加。本研究在改善牦牛酸乳品质的同时提升了产品的附加值，为PAPE的开发利用提供了新思路。

关键词: 蕨麻多糖提取物；牦牛酸乳；发酵；抗氧化