Evaluation of fermentation profiles of starches from different plant sources in an in vitro batch culture

Abstract

The influence of starches containing different levels of resistant starch (RS) on short chain fatty acid formation after fermentation was investigated in an in vitro batch culture. Native starches of sago, sweet potato, potato, arrowroot, rice, wheat, corn, as well as tapioca, cassava pulp and sweet potato root meal were evaluated in buffered caecal inoculum of 28-day old broiler chicks using the cumulative gas production technique. Total starch (TS), resistant starch (RS), short chain fatty acids: acetic, propionic and butyric acids. Short chain fatty acid ratios and fermentation ratios were estimated. Total and resistant starch content of the test starches and their short chain fatty acid profile: acetic, propionic and butyric acids- varied (p<0.05) amongst test starches. There was a strong relationship observed between proportions of acetic, butyric and propionic acids and total short chain fatty acids with R² values ranging from 0.97 to 0.99, However a weak relationship exist between proportions of acetic, butyric and propionic acids and resistant starch contents of the starches with R² ranging from 0.19 to 0.22, highlighting that variations in short chain fatty acid profiles of the fermented starches investigated in vitro was due to plant source rather than RS content of the test starches.

Keywords: Native starch; Resistant starch; Short chain fatty acids; Fermentation ratios; Caecal inoculum