干酪乳杆菌LK-1的发酵特性及其在菠萝果汁中的应用OACSTPCD

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.