不同乳酸菌对发酵桑葚汁酚类物质含量及抗氧化能力的影响

为提高桑葚（Morus alba L.）精深加工潜力，以嗜热链球菌（Streptococcus thermophilus）（ST）、保加利亚乳杆菌（Lactobacillus bulgaricus）（LB）、干酪乳杆菌（Lactobacillus casei）（LC）、植物乳杆菌（Lactobacillus plantarum）（LP）为发酵菌种，比较不同乳酸菌发酵桑葚汁的理化性质、单体酚类物质含量及抗氧化能力。结果表明，桑葚汁是四种乳酸菌优良的生长基质，发酵结束添加不同乳酸菌发酵的桑葚汁中活菌数皆超过11 lg（CFU/mL）。发酵过程总糖及还原糖含量明显下降，总酚及总黄酮含量显著提高。综合比较四种菌种的发酵能力，菌株LP的发酵性能最佳，发酵后桑葚汁中活菌数为12.5 lg（CFU/mL），总酚、总黄酮含量分别为7.4 mg没食子酸当量（GAE）/mL、4.5 mg芦丁当量（RE）/mL，1,1-二苯基-2-三硝基苯肼（DPPH）自由基清除率为65.3%，铁离子还原力（FRAP）为25.3 mg抗坏血酸当量（AAE）/mL，其抗氧化能力最强，菌株LP可作为桑葚发酵的最佳菌种应用于实际生产。

Effects of different lactic acid bacteria on phenolic contents and antioxidant capacity of fermented mulberry juice

In order to improve the deep processing potential of mulberry, using Streptococcus thermophilus (ST), Lactobacillus bulgaricus (LB), Lactobacillus casei (LC) and Lactobacillus plantarum (LP) as fermentation strains, physicochemical properties, phenolic contents and antioxidant capacity of mulberry juice fermented by different lactic acid bacteria were compared. The results showed that mulberry juice was an excellent growth substrate for 4 kinds of lactic acid bacteria, and the viable bacteria count in mulberry juice fermented by different lactic acid bacteria was more than 11 lg(CFU/ml) at the end of fermentation. The contents of total sugar and reducing sugar decreased significantly during the fermentation, while the contents of total phenols and flavonoids increased significantly. Comprehensively comparing the fermentation ability of 4 strains, the fermentation performance of strain LP was the optimal, and the viable bacteria count in mulberry juice after fermentation was 12.5 lg (CFU/ml). The contents of total phenols and flavonoids were 7.4 mg gallic acid equivalent (GAE)/ml and 4.5 mg rutin equivalent (RE)/ml, and the 1,1-diphenyl-2-nitrophenylhydrazide (DPPH) radical scavenging rate was 65.3%, the ferric reducing power (FRAP) was 25.3 mg ascorbic acid equivalent (AAE)/ml, its antioxidant capacity was the strongest, and the strain LP could be used as the optimal strain for mulberry fermentation.