Long‐term in vitro fermentation of high amylose starch digestion residues by human fecal inocula

Abstract

A three‐week in vitro anaerobic human fecal incubation system was used to screen fermentability of resistant starch residues (SRV, SRVI, SRVII) after amylase digestion for short chain fatty acid (SCFA) production and shifts in bacterial composition. Fermentation capacity was compared between lean (18.5<BMI<25, n=15) and overweight (BMI>25, n=15) subjects. All three SRs significantly increased gas production and decreased pH compared to blank (P<0.05), with no difference among treatments. The molar proportions of butyrate were similar among three SRs at 45%, which was significantly higher than that of the blank (20%, P<0.05), measured by GC. Higher propionate production was found from SRV compared to blank (P<0.05), whereas there was no significant difference between blank and SRVI or SRVII in propionate production. No significant difference was found in the individual or total SCFA production between lean and overweight subjects. Bifidobacterium, Lachnospiraceae and Bacteroidaceae spp. were enriched by SRs, revealed by PCR‐DGGE. In conclusion, a stable in vitro fermentation system was established. All three SRs increased butyrate production, but SRV differed from SRVI and SRVII with higher propionate production. No significant difference in the fermentation capacity of SRs was seen between lean and overweight subjects. Supported by Plant Sciences Institute, ISU.