Wheat Bran Sourdough as a Functional Ingredient

Several studies indicate that high-content whole grains diets work as a protective factor to chronic diseases. This decreased risk is related to the high content of fiber and bioactive compounds found mainly in the bran, which is usually removed during milling because of its fast rancidity. The increasing demand for functional foods and the pressure to ensure the exploitation of agro-industrial by-products have attracted great interest in bran-enriched foods/flours. The Healthgrain European Project recently emphasized the possibility to increase the amount of bioactive compounds in cereals by-products through biotechnological processes. Bran fermentation has been shown an efficient pre-treatment in order to enhance technological and nutritional properties of high fiber products (Katina et al. 2007). From a nutritional point of view, the fermentation effect on water-extractable arabinoxylans (WEAX) deserve particular attention, because of the positive effects on glycaemic and insulinaemic responses (Lu et al. 2000). Moreover, microbial xylan-degrading activity positively affects the bioavailability of functional compounds commonly found in the bran. This study aims to develop a innovative biotechnological process of wheat bran stabilization by microbial acidification. Briefly, bran sourdoughs were produced at 18 \ub0C through continuous propagation by back-slopping of ripe dough (10% inoculum) until a stable microbiota was established. At each refreshment step (every 24h), analysis of the bacterial content and the acidity of the dough, measured as pH and total titratable acidity (TTA), were performed on the ripe sourdough. Furthermore, the amounts of fiber and bioactive compounds, such as WEAX, ferulic and phytic acids, were determined before and after bran fermentation. Lactic acid bacteria (LAB) rapidly increased after the first day of bran fermentation and reached high amounts (109 CFU g-1). Yeasts population fluctuated during propagation, but after 8 refreshments it stabilized at the level of 107 CFU g-1. The TTA and pH developments followed the LAB growth with the pH rapidly decreasing from 6.5 to 4.1. Results suggest that wheat bran sourdough is a \u201cstable\u201d functional ingredient for bakery products that can be used to improve their nutritional and technological properties