Characterization of microbial polysaccharides and prebiotic enrichment of wheat bread with pullulan

The prebiotic efficacy of microbial polysaccharides pullulan, xanthan, and gellan was examined by in vitro digestion and in vitro fermentation. In vitro digestion study showed that pullulan exhibited a lower degree of hydrolysis (DOH) than xanthan and gellan. In vitro fermentation study showed that pullulan has improved the stimulating effect on the growth of probiotics. Thermo-gravimetric report showed the possible application of pullulan in bakery products. In this study, pullulan enriched bread formulations at varying concentrations with both refined wheat and wheat-based bread was done. Pullulan showed a positive correlation with probiotic growth and a negative correlation with water absorption. The nutritive value and physicochemical properties of the bread varieties were investigated. Bread samples with 2% pullulan exhibited most acceptable sensorial attributes, whereas the formulations with 8% and 10% pullulan were found to be much softer and darker. The in-vitro digestibility and fermentation of bread samples showed that Pullulan enriched breads were more resistant to hydrolysis by AGHJ than the standard bread samples. Prebiotic efficacy measured using Prebiotic Activity Score (PAS) was higher for pullulan among other polysaccharides and pullulan enriched breads against standard bread.