Nutritional enhancement of grain milling byproducts

The increasing demand for functional foods and the opportunity to take advantage of agro-industrial by-products have attracted great interest in bran-enriched products. The Healthgrain European Project has recently emphasized the possibility to enhance nutritional properties of cereal by-products through biotechnological processes. Bran fermentation has been shown to contribute to dietary fiber solubilization and positively affect the bioavailability of functional compounds. The fermentation effects on arabinoxylans (AX) deserve special attention because of the water-extractable arabinoxylans (WEAX) positive effects on glycemic and insulinemic responses and the arabyoxylan-oligosaccharides (AXOS) potential prebiotic properties. This study aims to improve bran nutritional properties through an innovative biotechnological process of fermentation involving sourdough in order to use the fermented bran as a functional ingredient. Wheat bran sourdoughs were produced through continuous propagation by back-slopping of ripe dough until a stable microbiota was established, reaching high counts of Lactic Acid Bacteria (LAB) and yeasts (109 and 107 CFU g-1 respectively). At each refreshment step, bacterial strains were isolated and identified by sequence analysis of partial 16S rRNA gene for LAB and D1/D2 domain of 26S rDNA for yeasts. Furthermore, the amounts of fiber, WEAX, free ferulic acid and phytic acid were measured. The amount of soluble fiber and WEAX significantly increased after sourdough, as did the level of free ferulic acid, probably due to microbial xylan-degrading activity, while the concentration of phytic acid decreased. Results suggest that fermented bran could be considered as an interesting functional ingredient for nutritional enhancement.