(578d) Chemical and Structural Characterization of Lactose-Derived Novel Galacto-Oligosaccharides – an in Vitro and In Vivo Prebiotic Activity Assessment

The present study focused on the development of a facile and high-yield process for converting lactose into prebiotic galacto-oligosaccharides (GOS) with health-promoting properties. Lactose was used as a substrate to synthesize GOS using concentrated sulfuric acid (64–84% H₂SO₄) as reaction medium via an acid-catalyzed glycosylation reaction. An optimal GOS yield of 96% with minimal residual side products (such as galactose, glucose, anhydro sugars, and sugar degradation products) was obtained by using an initial lactose loading of 50% w/w in 76% H₂SO₄ after reaction at 70 °C for 20 minutes. Characterization of GOS revealed the presence of di-, tri-, and tetra-saccharides (47%, 25%, and 16%, respectively) and a small portion of larger oligosaccharides (DP up to 6). In vitro fermentation studies demonstrated that GOS promoted the growth of selected Lactobacillus strains, such as Bifidobacterium bifidum -ATCC 29521 and Lactobacillus brevis -ATCC 8287, comparable to commercial GOS. In vivo experiments in 8-week-old mice models confirmed an 8- and 3-fold higher persistence of L. brevis with supplementation of synthesized GOS at the 4th and 8th day, respectively, post termination of the probiotic in the feed system. Future studies on the persistence of L. brevis with a combination of GOS and cows and goat milk individually can help advance our knowledge of the effect of oligosaccharides supplemented with different milk on the gut environment.