富含支链氨基酸的乳酸菌发酵乳清蛋白饮料的研制

The Development of Branched Chain Amino Acids-Containing Whey Based Beverage Fermented by LAB

该研究从分离自西藏传统发酵乳制品中的120株乳酸菌筛选到了5株具有较强乳蛋白分解能力的菌株,并对上述5株菌的凝乳能力、产酸特性、发酵后形成的风味和组织状态进行测试,筛选到一株兼具较强乳蛋白分解能力和良好发酵性能的乳酸菌P679,经鉴定该菌株是一株副干酪乳杆菌(Lactobacillus paracasei)。为了进一步改善该菌株的发酵性能,提高氨基酸产量,对复合乳蛋白发酵基质的成分进行正交优化,以乳清蛋白、脱脂乳、乳清粉添加量为主要因素,以终点p H值、蛋白水解度、游离氨基酸含量和感官评价为考量指标,获得三种乳蛋白原料的最优复配比例为WPC80为4%、脱脂奶粉为6%、风味乳清粉为5%。该菌株在此复配乳蛋白基料上发酵8h,能够显著提高游离氨基酸的含量,特别是支链氨基酸总量较发酵前提高了12.5倍,并在21d货架内具有较优的稳定性。

In this work, 120 lactic acid bacteria （LAB） strains isolated from Tibetan traditional fermented dairy products were chosen to investigate their hydrolysis ability of milk protein. By primary screening, we got five LAB strains with high proteolysis ability and excellent fermentation property. Subsequently, we studied the curding ability, acid-producing level and sensory characters of yogurt fermented by this five LAB strains above-mentioned and acquired the best LAB strains, Laetobaeillus paraeasei P679. We optimized the ratio of the fermented material including whey protein concentration 80 （WPC80）, skim milk and whey powder by the orthogonal experiment in order to improve the fermentation performance of this strain and free amino acid level of the final product. As a result, we obtained the optimum formula with 4% WPC80, 6% skim milk and 5% whey powder. The free amino acid level of the final product significantly increased by 12.5 times after 8h fermented by Lactobacillus paracasei P679 and the experiment also proved that the level of free amino acid was stable within 21 days.