添加瑞士乳杆菌对发酵牦牛乳抗氧化能力的影响

Effect of Lactobacillus helveticus on antioxidant capacity of fermented yak milk

添加瑞士乳杆菌(Lactobacillus helveticus,Lh)与嗜热链球菌-德氏乳杆菌保加利亚亚种发酵剂(Streptococcus thermophilus-Lactobacillus bulgaricus,Y)单独或共培发酵,研究Lh不同接种量对牦牛乳的发酵特性、以及发酵牦牛乳的抗氧化能力与肽含量及蛋白水解活力之间的关系。研究发现,Lh与Y混合发酵能使牦牛乳更快凝乳,凝乳时间为2.67 h;在整个冷藏期间,DPPH自由基清除能力和羟自由基清除能力分别与肽含量呈极显著相关(P<0.01),均表现为先上升后下降的趋势,于第14天达到最大值(P<0.05),其中5%Lh-Y组的DPPH自由基清除能力最强,为93.95%,同时该组样品的羟自由基清除能力最强,为81.83%;Fe2+螯合能力表现为下降趋势,分别与肽含量、蛋白水解活力呈极显著相关(P<0.01),5%Lh组样品的螯合能力最强;还原能力表现为上升趋势,与蛋白水解活力呈显著相关(P<0.05),5%Lh-Y组的还原能力最强。结果表明,Lh与Y混合培养能够显著提高发酵牦牛乳样品的抗氧化能力,瑞士乳杆菌在功能性发酵牦牛乳加工中有较好的应用前景。

Lactobacillus helveticus(Lh)and Streptococcus thermophilus-Lactobacillus bulgaricus starter(Y)were added separately or co-cultured for fermentation.The effects of different inoculation amounts of Lh on fermentation characteristics,and the relationship between antioxidant capacity and peptide content and proteolytic activity of fermented yak milk were studied.The results showed that the co-fermentation of Lh and Y could make yak milk coagulate faster,with a coagulating time of 2.67 h.During the whole cold storage period,the DPPH free radical scavenging ability and hydroxyl free radical scavenging ability were significantly positively correlated with the peptide content(P<0.01),both of which showing a trend of first increase and then decrease,reaching the maximum on the 14 th day(P<0.05).Among them,the DPPH free radical scavenging ability of the 5%Lh-Y group was the strongest,which was 93.95%,and the hydroxyl free radical scavenging ability of the group was the strongest,which was 81.83%.The chelating ability of Fe2+showed a downward trend,which was significantly positively correlated with peptide content and proteolysis activity(P<0.01),and the chelating ability of 5%Lh group was the strongest.The reducing power showed an increasing trend and was significantly correlated with proteolytic activity(P<0.05).The reducing power of 5%Lh-Y group was the highest.The study suggests that co-culture of Lh and Y can significantly improve the antioxidant capacity of fermented yak milk samples,and Lactobacillus helveticus has a good application prospect in functional fermented yak milk processing.