Lactosucrose and its analogues derived from lactose and sucrose: Influence of structure on human intestinal microbiota in vitro

Lactosucrose (β-D-Galp-(1→4)-α-D-Glcp-(1→2)-β-D-Fruf) and its analogues (iso-lactosucrose,β-D-Galp-(1→3)-α-D-Glcp-(1→2)-β-D-Fruf; 4′-galactosyl-lactosucrose,β-D-Galp-(1→4)-β-D-Galp-(1→4)-α-D-Glcp-(1→2)-β-D-Fruf), and 4′-galactosyl-lactose (β-D-Galp-(1→4)-β-D-Galp-(1→4)-α,β-D-Glcp) were synthesized by Bacillus circulans β-D-galactosidase-mediated transglycosylation with lactose and sucrose as the substrates. The prebiotic properties and stimulation of short chain fatty acid (SCFA) production of these oligosaccharides were then evaluated by in vitro fermentation of human intestinal microbiota. The results showed that the two analogues (4′-galactosyl-lactosucrose and iso-lactosucrose) of lactosucrose seemed to present potential prebiotic activity, as they exhibited high values of selectivity index with increasing the populations of bifidobacteria and lactobacilli, even higher than lactosucrose as well as 4′-galactosyl-lactose. In addition, the bacterial metabolism with iso-lactosucrose produced the highest contents of acetic and lactic acids (38.55 and 37.19 mM, respectively), which resulted in the greatest amounts of total SCFA (105.13 mM) followed by 4′-galactosyl-lactose (99.82 mM) and 4′-galactosyl-lactosucrose (99.28 mM). The results indicated that the two analogues of lactosucrose might represent a suitable alternative to lactosucrose for the design of new functional food ingredients.