Effects of initial pH on heat resistance of Lactobacillus plantarum LIP-1

Abstract

In order to study the effect of different initial pH values on heat resistance of the strain, the changes in heat stress survival rates of Lactobacillus plantarum LIP-1 and its potential influencing mechanisms were investigated under different initial pH values. The results showed that the growth L. plantarum LIP-1 did not significantly differ according to initial pH value (P > 0.05), but there were significant differences in heat stress survival rates among initial pH values (P < 0.05). Further analysis revealed that a suitable initial pH value could improve the relative proportion of unsaturated fatty acids in the cell membrane and increase the ratio of unsaturated to saturated fatty acids (U/S), reduce the thermal damage to cell membrane, and improve heat stress survival of the strain. The adjustment of cell membrane fatty acid composition is related to the acidic stress environment caused by the rapid growth of L. plantarum LIP-1 under suitable initial pH conditions. The results confirmed that a suitable initial pH value could improve the heat resistance of the strain. Accordingly, this study provides a theoretical reference for improving the spray drying of probiotics by changing the culture conditions.