Factors Involved in theIn VitroFermentability of Short Carbohydrates in Static Faecal Batch Cultures

In recent years, research has focused on the positive effects of prebiotics on intestinal health and gut microbiota. The relationship between their chemical structure and their fermentation pattern by human intestinal microbiota is still not well understood. The aim of this study was to improve understanding of this relationship and identify factors that may be used to design galactooligosaccharides that reach more distal regions than commercial prebiotics which mainly target the proximal colon. The following factors were investigated: monomer type, linkage, substitution, and degree of polymerisation. Total organic acid production from sugars by faecal bacteria was fitted to a model which allowed an estimate of the time when half of the maximal organic acid concentration was reached (T50) in static faecal batch cultures. The different factors can be grouped by their effectiveness at prolonging fermentation time as follows: substitution is most effective, with methylgalactose, β-galactose-pentaacetate, D-fucose, and galactitol fermented more slowly than D-galactose. Monomers and linkage also influence fermentation time, with L rhamnose, arabinose, melezitose, and xylose being fermented significantly slower than D-glucose (P<0.05), maltose, isomaltose, cellobiose, and gentiobiose showing that Glcα1-6Glc and Glcβ1-4Glc were utilised slowest. Chain length had the smallest effect on fermentation time