Effects of Lactobacillus fermentation on the composition, existing forms, digestive characteristics, and antioxidant activity of polyphenols in three kinds of bean milk

Abstract

Soy, peanut and chickpea contain polyphenols that have multiple beneficial biological activities. In this work, two Lactobacillus strains were employed to ferment the three kinds of bean milk and the effects of fermentation on the polyphenols in them were investigated. After fermentation with L. fermentum GD01 and L. plantarum BHP03, the total phenolic contents were increased by 16.90 % and 14.64 % in soy milk, 18.14 % and 24.28 % in peanut milk, 46.39 % and 51.91 % in chickpea milk, respectively. Specifically, the contents of free phenol, insoluble ester phenol, and insoluble glycosidic phenol increased, while the contents of soluble ester phenol and soluble glycosidic phenol reduced. These changes were positively associated with the antioxidant activities. Further, Lactobacillus fermentation also changed the contents and forms of monomeric phenols in bean milk, with the free monomeric phenols exhibiting the greatest diversity in types. In addition, the fermented bean milk demonstrated a higher release of phenols compared to the unfermented counterparts during simulated digestion, resulting in enhanced antioxidant activities. Notably, the most substantial increase in soluble phenols was detected in fermented chickpea milk (162.66 % by GD01, 137.48 % by BHP03), while the most significant increase in insoluble phenols was observed in fermented peanut milk (147.46 % by GD01, 150.53 % by BHP03). All the results confirmed that Lactobacillus fermentation could alter the structures, compositions, digestive characteristics of the polyphenols in the three kinds of bean milk, ultimately enhancing their antioxidant activities. These results offer a theoretical foundation for the advancement of fermented bean milk products with enhanced biological activity.