In vitro fermentation of a retrograded maize starch by healthy adult fecal extract and impacts of exogenous microorganisms on three acids production

The impacts of 14 exogenous microorganisms on simulated colonic fermentation and acid production of a retrograded maize starch were studied in the present work. A commericial high-amylose maize starch (Hylon VII) was treated by three autoclavingcooling cycles. The obtained retrograded starch contained RS of 29.4% w/w, was used as RS-containing substrate for an in vitro fermentation by healthy adult fecal extract at 40g/L and 37 degrees C for 36h. GC analysis showed that acetic, propionic and butyric acid generated in the fermentation system were about 8.8, 2.7, and 3.2mM, respectively. Fermented jointly by the fecal extract and one of nine prepared microorganism cultures, the retrograded starch yielded more acetic acid ranging from 16.0 to 20.3mM. Addition of one culture from Enterococcus faecalis, E. faecium, Bifidobacterium infantis, or B. longum other than other strains resulted in propionic and butyric acid production near to 9mM in the fermentation system, showing favorable impacts of the four strains on two acids production. It is suggested that some microorganisms can mediate acid production during conlonic fermentation of RS or RS-containing products, and the interaction between prebiotics and probiotics in colon-targeted functional foods should be investigated.