Evidence of membrane lipid oxidation of spray-dried Lactobacillus bulgaricus during storage

Membrane fatty acids of Lactobacillus bulgaricus were analysed by gas-liquid chromatography before and after spray drying. The ratio unsaturated/saturated fatty acids decreased following spray drying, indicating the formation of lesions in cellular lipid-containing structures. The same method was used to analyse membrane lipids of Lact. bulgaricus during storage. Similarly the ratio of unsaturated/saturated fatty acids in dried cells decreased further during storage in air, presenting evidence of lipid oxidation after prolonged storage. The mechanisms of cell death during storage in the dried state are still unknown, but from these results and those presented in the literature, it seems evident that lipid oxidation and survival during storage may be related.