Probiotic Fermentation to Improve Nutritional Profile in Extruded or Ground Corn and Wheat Brans

Abstract

Corn bran and wheat bran are coproducts of corn and wheat milling operations, respectively, and have lower commercial value mostly as animal feeds. They are rich sources of dietary fiber and phenolics. In this research, the effect of two physical modifications of wheat and corn brans 1) extrusion at two die temperature settings (140 and 120°C), and 2) grinding to < 500mm were evaluated on fermentation by Lactobacillus plantarum and Bacillus subtillis. Color measurement for extruded brans showed lower L* (lightness) and higher a* and b* (red/green and yellow/blue) when compared with the ground control brans. The diameter of the extruded brans at 25% moisture content was 3.3 mm and 3.49 mm for wheat and corn bran, respectively, compared to 3.0 mm 3.17 mm for wheat- and corn brans at 35% moisture. For fermentation performance, the extruded or ground brans were dispersed in water at 1:10 w/v, pH adjusted to 6.5 and pH 7, autoclaved at 121°C for 30 min, and inoculated (1% v/v) with L. plantarum and B. subtillis, respectively. The fermentation was carried out in 500 mL shake flasks at 37°C for 72 h with shaking at 200 rpm; 10 mL samples were taken out at 0, 6, 12, 24, 48, and 72 h time intervals for microbial viability and pH measurement. All the extruded or ground brans supported the growth of probiotic bacteria, which are expected to modify bran matrix favorably in making dietary/ nutrition components easily available for digestion.