Oxidative stability of milk and soy milk fatty compound induced by Lactobacillus plantarum fermentation during refrigerated period Sahar Torki Baghbadorani

In recent years، substitution of soy milk with cow milk in the individuals'' diet suffering from inflammatory diseases have been considered in clinical studies. However، soy milk is more prone to oxidation compared to cow milk due to its unsaturated fatty acid. Oxidative stability of soy milk fat and its comparison with cow milk fat has been barely discussed in the literature. Present study aimed at comparing the oxidative stability of commercial pasteurized milk and soy milk samples and their fermented counterparts by L. plantarum A7 during 14 days refrigerated period. Commercial pasteurized milk and soy milk with the same concentration of fatty compound were subjected to fermentation using a native lactobacillus strain، Lactobacillus plantarum A7. Peroxide number and thiobarbitoric acid in the four trials including milk، soymilk، fermented milk and fermented soy milk were investigated during 14 days of cold storage in the controlled condition. The results showed that milk and soy milk fermentation by Lactobacillus plantarum significantly reduced the amounts of both oxidative indices. In non fermented products، peroxide value was found to increase by a similar trend، reaching to the pick after five days of refrigeration. No significant difference was observed between such an increase between milk and soy milk. Instead، TBA value was measured at higher level in soy milk samples all through the study period. Discussion and Despite the higher non saturated fatty acid، soy milk appeared to be as sensitive as milk regarding oxidative damage، However، comparing the great impact of fermentation on retarding oxidation، the difference between no fermented products can be regarded as negligible.