Characterization of Bestak sweet potato (Ipomoea batatas) variety from Indonesian origin as prebiotic

The objectives of this study were to analyze the macronutrients composition, dietary fiber, and resistant starch in Bestak sweet potato variety; to identify the prebiotic components in sweet potato fiber extract (SPFE); and to evaluate the prebiotic activity of SPFE. Evaluation of prebiotic activity was based on the change in cell biomass after 24 h of growth of the probiotic strain in the presence of SPFE, inulin, fructooligosacharide, or glucose relative to the change in cell biomass of Escherichia coli grown under the same condition. Prebiotic activity was calculated for L. plantarum Mut7 and Bifidobacterium longum JCM 1217. The results showed that ash, starch, and total carbohydrate in SPFE were lower than in the raw sweet potato and its powder. However the crude protein in SPFE was higher than in the raw sweet potato and its powder. SPFE contained 3.50% soluble fiber, 12.17% insoluble fiber, 22.23% resistant starch, and 37.90% total dietary fiber. The increasing cell number of L. plantarum Mut7 was higher in the SPFE substrate (3.21 log CFU/ml), whereas B. longum grew better in FOS substrate (2.19 log CFU/ml). The highest prebiotic activity score was obtained for L. plantarum Mut7 grown on SPFE (1.62), whereas the lowest score was for Bifidobacterium longum grown on inulin (0.47). It can be concluded that Bestak sweet potato variety has potency as prebiotic source because it contains FOS, inulin and raffinose. The SPFE has prebiotic activity score that similar to FOS, but it was higher than inulin.