干酪乳杆菌LK-1的发酵特性及其在菠萝果汁中的应用

Fermentation Characteristics of Lactobacillus casei LK-1 and Its Application in Pineapple Juice

为利用干酪乳杆菌制备发酵菠萝果汁饮品,本研究对干酪乳杆菌LK-1(Lactobacillus casei LK-1,L. casei LK-1)的生长曲线、产酸、耐酸和耐糖等特性进行研究分析,并以活菌数和总酸为指标,通过单因素实验及响应面法考察L. casei LK-1发酵菠萝果汁的最佳条件。结果表明,L. casei LK-1在pH5~7和0%~10%质量分数葡萄糖环境下,具备良好的生长繁殖能力;在酸性(pH3)和高糖(40%质量分数葡萄糖)环境中培养3 h,其存活率分别为76%和71%;在MRS培养基中培养48 h,产酸量为5.35 g/kg,产酸能力良好,适用于果汁的发酵。L. casei LK-1发酵菠萝果汁的最佳条件为:初始pH6.8,发酵温度37℃,接种量1%(v/v),发酵时间30 h,此条件下制备的发酵菠萝果汁饮品活菌数为8.99±0.04 lg CFU/mL,总酸含量为7.16±0.26 g/kg,且色泽鲜亮,酸甜适口,风味较好,为L. casei LK-1在发酵食品中的进一步应用提供了理论和技术依据。

In order to utilize Lactobacillus casei to prepare fermented pineapple juice beverage,the growth curve,acid production,acid tolerance,and sugar tolerance characteristics of Lactobacillus casei LK-1(L.casei LK-1)were investigated and analyzed in this research.Moreover,the optimal conditions for the fermentation of pineapple juice by L.casei LK-1 were explored by single-factor test and response surface methodology,with the viable cell count and total acid content as indicators.As revealed by the results,L.casei LK-1 grew and reproduced well in an environment with pH5~7 or containing 0%to 10%glucose.The survival rates of it were 76%and 71%,respectively,after 3 h of incubation in an acidic(pH3)or high sugar(40%glucose)environment.Besides,after 48 h incubation in MRS medium,its acid production was 5.35 g/kg,which was good for the fermentation of the juice.The optimal conditions for fermenting pineapple juice with L.casei LK-1 were:Initial pH of 6.8,fermentation temperature of 37℃,inoculum level of 1%(v/v),as well as fermentation time of 30 h.Under this preparation condition,the viable cell count of fermented pineapple juice was 8.99±0.04 lg CFU/mL,the total acid content was 7.16±0.26 g/kg,and the juice was bright in color,sweet and sour with excellent flavor.The results of this research can provide a theoretical and technical basis for the further application of L.casei LK-1 in fermented foods.