Short-chain fatty acids produced in vitro from fibre residues obtained from mixed diets containing different breads and in human faeces during the ingestion of the diets

It was studied whether the type of bread (i.e. a low-fibre wheat-rye mixed bread and coarse or fine wholemeal rye bread) either as part of a diet or a lone, had an influence on the short-chain fatty acids (SCFA) produced durin g in vitro fermentation. Fermentation substrates were dietary fibre residue s obtained from diets and breads. In addition, it was investigated whether the faecal SCFA pattern in the inoculum donors, who ingested the experiment al diets, could be predicted by in vitro fermentation. Yields of SCFA in vi tro were 0.51-0.62 g/g fermented polysaccharide. In vitro, the molar ratios of butyrate were higher for the two high-fibre diets containing coarse or fine wholemeal bread than for the low fibre diet containing wheat-rye mixed bread; the difference was significant for the coarse (P < 0.01), but not f or the fine bread diet (P = 0.0678). The coarse wholemeal bread alone produ ced a higher molar ratio of butyrate than the fine wholemeal bread (P < 0.0 5) and the wheat-rye mixed bread (P < 0.01). Ingestion by the inoculum dono rs of the diets containing wholemeal bread led to higher faecal butyrate ra tios (molar ratios: coarse bread diet 19.6, fine bread diet 17.7) compared with the wheat-rye mixed bread-containing diet (14.9), but the differences between the diets were not significant. For the diets investigated, there w ere no significant differences between faecal and in vitro SCFA patterns.