Reduction of alpha-galactooligosaccharides in soyamilk by Lactobacillus fermentum CRL 722: in vitro and in vivo evaluation of fermented soyamilk.
Consumption of soya-derived products has been hampered by the presence of alpha-galactooligosaccharides (alpha-GOS) because mammals lack pancreatic alpha-galactosidase (alpha-Gal) which is necessary for their hydrolysis. These sugars thus reach the large intestine causing gastrointestinal disorders in sensitive individuals. The use of lactic acid bacteria (LAB) expressing alpha-Gal is a promising solution for the degradation of alpha-GOS in soyamilk. The capacity of the LAB Lactobacillus fermentum CRL 722 to properly degrade alpha-GOS was studied in vitro using controlled fermentation conditions and in vivo using a rat model. Lactobacillus fermentum CRL 722 was able to grow on commercial soyamilk and completely eliminated stachyose and raffinose during fermentation because of its high alpha-Gal activity. Rats fed soyamilk fermented by this LAB had smaller caecums compared with rats fed unfermented soyamilk. Soyamilk fermentation by Lact. fermentum CRL 722 results in the reduction of alpha-GOS concentrations in soyamilk, thus eliminating possible undesirable physiological effects normally associated with its consumption. Fermentation with Lact. fermentum CRL 722 could prevent gastrointestinal disorders in sensitive individuals normally associated with the consumption of soya-based products. This LAB could thus be used in the elaboration of novel fermented vegetable products which better suit the digestive capacities of consumers.