In vitro digestibility of oligosaccharides synthesized by dairy propionibacteria β-galactosidase from lactose, lactulose and lactitol

Abstract

Prebiotics synthesized by probiotic genera are of interest due to their specific selectivity. However, modifications of their composition and concentrations by digestion may affect their properties and effects in the host. In the present study we assessed small intestinal digestibility of oligosaccharides synthesized by Acidipropionibacterium acidipropionici LET120-β-gal (β-galactosidase) from lactose (LET120-GOS), lactulose (LET120-OsLu) and lactitol (LET120-LOS) by incubating them with brush border membrane vesicles (BBMV) from pig and a rat small intestinal extract (RSIE) as in vitro models of mammalian mucosa. Both BBMVs and RSIE partially degraded the potential prebiotic oligosaccharides synthesized by dairy propionibacteria and hydrolysis was influenced by the structure and composition of the oligosaccharides. The highest degradation was observed for LET120–GOS, with 46.8% and 58.1% of hydrolysis after 5 h of digestion with BBMV and RSIE, respectively. On the contrary, LET120-OsLu and LET120-LOS showed higher resistance to intestinal degradation. β(1 → 6) linked products showed higher resistance to mammalian digestive enzymes compared to β(1 → 4) and β(1 → 3) linked oligosaccharides. Results emphasize the need of quantifying prebiotics that would reach the colon to anticipate their impact on health and the dose needed to exert that effect.