The screening method of a bifidogenic dietary fiber extracted from inedible parts of vegetables.

Total dietary fiber (DF) was extracted from the inedible parts of vegetables such as peel of taro and Chinese yam, pea pod, broad bean pod, and broad bean testa. Effects of these fibers on the growth of bifidobacteria were determined by two kinds of experiments: one was to determine the increase of Bifidobacterium longum JCM1217 (B. longum) in medium containing DF, the other was an in vitro fermentation of the DF by anaerobic slurries of mixed human fecal or rat cecal microbiota. Anaerobic culture was carried out for 48 h in both experiments. In the pure culture of B. longum, the significant increase of bacterial number was observed as compared with 0 h in the medium containing the DF from peel of Chinese yam, pea pod and broad bean pod (p<0.05). On the other hand, bacterial number was decreased in the medium containing the DF from the peel of taro and broad bean testa. We selected the DF from pea pod because of its highest bifidogenic property in human fecal microbiota. In the fermentation of DF from pea pod by rat cecal microbiota, bifidobacteria and lactobacilli were increased. Bacteroidaceae and clostridia were decreased. These results suggested that DF from pea pod had possibility as a prebiotic. The bifidogenic property was affected by the sugar composition of DF.