PRIOR EXPOSURE OF CECAL MICROFLORA TO GRAPE POMACES DOES NOT INHIBIT IN-VITRO FERMENTATION OF PECTIN

Grape pomace is mainly composed of dietary fiber (DF) and polyphenols (PP), components of the undigestible residue and substrates for coloni c fermentation. Male Wistar rats were fed fiber-free diets supplemente d with 5% cellulose or 10% red grape peels (RGP), white grape peels (W GP), or white grape seeds (WGS) as source of DF for 6 weeks, and rat c ecal contents from fasted rats were used as inoculum to in vitro ferme nt apple pectin. Short-chain fatty acid (SCFA) production, pH, and pre ssure were measured as indications of fermentative capacity at differe nt times. SCFA production at 24 h, expressed as micromoles per milligr am of dry substrate, was significantly higher in RGP (9.1) and WGS (9. 6) groups than in the control group (8.8). Fermentative capacity of ce cal contents from WGP-fed rats did not differ from that of the central group (8.5 mu mol/mg of dry substrate). The presence of the three tes t materials in the diets did not modify the fermentation rate. SCFA pr oduction was significantly correlated with pH values (r=-0.969) and ga s production (r = 0.960). In conclusion, DF rich in PP did not inhibit colonic fermentation: furthermore, some materials enhanced the proces s.