以感官评价得分及酸度为评价指标，利用单因素及正交试验方法确定槲皮素酸奶的最佳发酵条件和最优配方。通过检测酸奶乳酸菌总数，探究槲皮素对酸奶菌群的影响。动态观察槲皮素酸奶对小鼠肠道菌群乳杆菌、双歧杆菌、肠杆菌和肠球菌体外增殖的影响。实验证明，槲皮素酸奶最佳发酵条件和工艺配方为：发酵时间为8 h，发酵温度为42 ℃，发酵剂接种量为0.1%，乳粉添加量为12%，蔗糖添加量为4%，槲皮素添加量为0.1%，所制得的槲皮素酸奶色泽均匀，呈黄绿色，酸甜适口，带有愉悦的轻微苦味（可能来自添加的槲皮素和某些蛋白水解产生的肽）。槲皮素酸奶中乳酸菌总数为（1.475±0.005）×108 cfu/mL，高于原味酸奶乳酸菌总数（p<0.05）。观察动态微生物变化，发现小鼠肠道菌群体外增殖的变化，槲皮素酸奶处理组的乳杆菌和双歧杆菌的生长曲线高于原味酸奶处理组，而肠杆菌和肠球菌的生长曲线低于原味酸奶处理组。结果表明最优工艺条件下制得的槲皮素酸奶能促进小鼠乳杆菌和双歧杆菌体外增殖、抑制肠杆菌和肠球菌体外增殖，且口感优于市售酸奶。本研究结果为槲皮素功能酸奶的后续开发利用提供理论依据。

Using sensory evaluation score and acidity as evaluation indices, the optimal fermentation conditions and optimal formula of quercetin-fortified yoghurt were determined by the single factor and orthogonal test methods. The effect of quercetin on the microbes in the yoghurt was investigated by measuring the total number of lactic acid bacteria of yogurt. Examinations were performed on the dynamic changes in the microbial community induced by quercetin-fortified yoghurt i.e. the proliferation of Lactobacillus, Bifidobacterium, Enterobacter and Enterococcus in mice. The experiments revealed that the optimal fermentation conditions and formula of quercetin-fortified yoghurt were: fermentation time 8 h, fermentation temperature 42 ℃, inoculation dosage 0.1%, added milk powder 12%, added sucrose 4%, and added quercetin added 0.1%. The obtained quercetin-fortified yoghurt had uniform color (yellow-green color) and sweet-sour balanced taste, with a pleasant and slight bitterness (which likely came from the added quercetin and some peptides derived from protein hydrolysis). The total number of lactic acid bacteria in quercetin-fortified yoghurt was (1.475±0.005)×108 cfu/mL, which was higher than that for the unfortified yogurt (p<0.05). Observations on the dynamic microbial changes revealed the alterations in the proliferation of intestinal flora in mice: the growth of Lactobacillus and Bifidobacterium in the quercetin-fortified yogurt was stronger while the growth of Enterobacter and Enterococcus was weaker, compared with that of unfortified yogurt. The results showed that the quercetin-fortified yoghurt prepared under the optimal conditions could promote the proliferation of Lactobacillus and Bifidobacteria in vitro but inhibit the proliferation of Enterobacter and Enterococcus in vitro, with its taste better than that for the commercially available yoghurt. The results of this study provide a theoretical basis for the subsequent development and utilization of quercetin-fortified functional yogurt.

国家自然科学基金面上项目（81773428）；广东省自然科学基金项目（2016A030313597）