Survival of Freeze-dried Leuconostoc mesenteroides and Lactobacillus plantarum Related to Their Cellular Fatty Acids Composition during Storage

Lactic acid bacteria strains Lactobacillus plantarum CWBI-B534 and Leuconostoc ssp. mesentero < des (L. mesentero < des) Kenya MRog2 were produced in bioreactor, concentrated, with or without cryoprotectants. In general, viable population did not change significantly after freeze-drying (p > 0.05). In most cases, viable population for cells added with cryoprotectants was significantly lower than those without (p < 0.05). Cellular fatty acids (CFAs) from the two strains in this study were analyzed before and after freeze-drying. Six CFAs were identified, namely, palmitic (C-16:0), palmitoleic (C-16:1), stearic (C-18:0), oleic (C-18:1), linoleic (C-18:2), and linolenic (C-18:3) acids were identified. Four of them, C-16:0, C-16:1, C-18:0, and C-18:1, make up more than 94% or 93% of the fatty acids in L. mesenteroides and L. plantarum, respectively, with another one, namely, C18:3, making a smaller (on average 5-6%, respectively) contribution. The C-18:2 contributed very small percentages (on average a parts per thousand currency signaEuro parts per thousand 1%) to the total in each strain. C-16:0 had the highest proportion at most points relative to other fatty acids. Moisture content and water activity (a (w)) increased significantly during the storage period. It was observed that C-16:1/C-16:0, C-18:0/C-16:0 and C-18:1/C-16:0 ratios for freeze-dried L. mesenteroides or L. plantarum, with or without cryoprotectants, did not change significantly during the storage period. According to the packaging mode and storage temperatures, C-18:2/C-16:0 and C-18:3/C-16:0 ratios for freeze-dried L. mesenteroides and L. plantarum with or without cryoprotectants decreased as the storage time increased. However, a higher C-18:2/C-16:0 or C-18:3/C-16:0 ratio for L. mesenteroides and L. plantarum was noted in the freeze-dried powder held at 4 A degrees C or under vacuum and in dark than at 20 A degrees C or in the presence of oxygen and light.