<i>In Vitro</i> Digestibility of Galactooligosaccharides: Effect of the Structural Features on Their Intestinal Degradation

Small intestinal brush border membrane vesicles from pig were used to digest galactooligosaccharides from lactose (GOS) and from lactulose (OsLu). Dissimilar hydrolysis rates were detected after digestion. Predominant glycosidic linkages and monomeric composition affected the resistance to intestinal digestive enzymes. The β(1→3) GOS mixture was the most susceptible to hydrolysis (50.2%), followed by β(1→4) (34.9%), whereas β(1→6) linkages were highly resistant to digestion (27.1%). Monomeric composition provided a better resistance in β(1→6) OsLu (22.8%) compared to β(1→6) GOS (27.1%). This was also observed for β-galactosyl fructoses and β-galactosyl glucoses, where the presence of fructose provided higher resistance to digestion. Thus, the resistance to small intestinal digestive enzymes highly depends upon the structure and composition of prebiotics. Increasing knowledge in this regard could contribute to the future synthesis of new mixtures of carbohydrates, highly resistant to digestion and with potential to be tailored prebiotics with specific properties, targeting, for instance, specific probiotic species