Impact of pectin and alginate gel particle size and concentration on in vitro gut fermentation

Fermentation by human gut microbiota of dietary fibres (DF) is influenced by the particle size and concentration of these fibres. However, previous studies have faced challenges in investigating these effects in real food systems due to the complex composition and heterogeneous structure of most DF. Here we describe particle size and concentration effects on the fermentation of polysaccharide gel particles, used as examples of defined and homogeneous model DFs. Gel particles of calcium-induced gelling polysaccharides, alginate and pectin, were prepared using dripping (>1 mm) and emulsion-based (1 mm) of alginate and pectin fermented more slowly than solutions.•Pectin fermented faster than alginate in both gel and solution forms.•Size and concentration had little effect on fermentation for particles of 1–4 mm.•Pectin particles of ∼0.5 mm fermented similarly to solutions.