Fermentative fate of starches in non-ruminant animals: An evaluation with intestinal microflora in vitro

The influence of starches on gut health has triggered interest in their fermentative fate. Ten starches were evaluated for their fermentability in buffered caecal inoculum using the cumulative gas production technique. Total short-chain fatty acids (TSCFA), lactic acid and branched chain ratio (BCR) were analyzed post-fermentation and "actual hindgut fermentation" (AHF) index was estimated by deducting foregut digestibility estimated by an enzymatic model from 'in vitro' fermentability. The highest TSCFA values were recorded for rice starch (50.66 μmol/ml) and least for potato starch (14.53 μmol/ml), however, highest lactic acid was recorded for wheat starch (3.18 μmnol/ml) while no lactic acid was detected during fermentation of potato and rice starches, hinting at their inability to support proliferation of lactic acid-producing bacteria 'in vivo'. Low BCR-ratio of protein to carbohydrate fermentation were also recorded, an indicator of minimal protein fermentation. Furthermore, AHF indices alluded to the fact that better fermentability will be supported by tapioca, sweet potato starch, corn starch, cassava pulp and wheat starch 'in vivo'.