CONICET | Buscador de Institutos y Recursos Humanos

Whole grain wheat flour (WWF) has a higher dietary fiber content than refined flour. Arabinoxylans (AX) are part of this dietary fiber and they have received attention given their emergent prebiotic character. The objective of this work was to evaluate the in vitro prebiotic effect of a raw WWF, a previously digested WWF and a water-soluble AX extract (WSAX). An in vitro flour digestion simulating oral, gastric, and intestinal steps was used to prepare the digested WWF. Arabinose∕xylose rate of WSAX extract was determined. Quantitative scores were calculated to describe the extent to which raw WWF, digested WWF, and WSAX extract support selective growth of Bifidobacterium and Lactobacillus strains in a defined media. Inulin (IN) was included as a positive control. The prebiotic activity (PA) was determined considering the growth ratio relative to the glucose of probiotic strains as well as of the enteric bacteria Escherichia coli, when raw WWF, digested WWF or WSAX were used as C source. Moreover, the bacterial growth of Clostridium and Bacteroides strains were assessed. For prebiotic index (PI), the bacterial growth of Bifidobacteria, Lactobacilli, clostridia and bacteroides were entered into the PI equation to determine a quantitative PI score. WSAX extracts promoted a higher relative growth for Lactobacilli (PA: WSAS 0,37 vs. IN 0.18) and Bifidobacteria (PA: WSAS 0.36 vs. IN 0,28) compared with inulin, which resulted in positive values. Digested WWF showed higher PA for Bifidobacteria (PA 3.77) but lower for Lactobacilli (PA 0.03) compared with WSAX. No prebiotic activity for raw WWF was found. The PI value for WSAX was higher than the value obtained with commercial IN (4.09 vs. 2.62). Digested WWF presented a very low PI. These results suggest that WSAX extracts could be used as a prebiotic food ingredient, and thus to evaluate their ability to modulate microbiome in vivo becomes interesting.