In vitro fecal fermentation of indigestible residues from heat-moisture treated maize meal and maize starch with stearic acid

Abstract

The effect of resistant starch type 5 (amylose-lipid complex, ALC) from maize starch and maize meal on short-chain fatty acids (SCFAs) production by in-vitro human faecal fermentation are determined. The maize starch and meal are modified using heat-moisture treatment (HMT), stearic acid (SA), and combination treatment (SA+HMT) and digested to obtain indigestible residues. The results showed the production of SCFAs (acetate, propionate, and butyrate) from indigestible residues containing amylose-lipid complexes during the process of in vitro faecal fermentation. The concentrations of three SCFAs are lower than fructooligosaccharides (control) in most cases. In regard to the indigestible residues, the combination treatment has a significantly higher concentration of the total SCFAs than the individual SCFAs produced by different treatments and the control. Reduction in pH with increased gas production is observed. Acetate and butyrate levels are higher than propionate values of RS 5 from maize starch and meal. A positive correlation between the gas produced and SCFAs (acetate, propionate, and butyrate) is noticed, however it resulted in negative correlation with pH. In conclusion, indigestible residues containing ALC (or RS 5) produced SCFAs during in vitro faecal fermentation, suggesting that ALC are suitable substrates for fermentation in the lower gut.