Fermentation performance of Lactobacillus plantarum and Bacillus subtilis in ground or extruded corn bran and resulting constituents

Abstract

The effects of two physical modifications of corn bran, namely, 1) grinding to < 500 μm and 2) extruding at two die temperature settings (high, 140 °C and low, 120 °C) were evaluated on growth performance of Lactiplantibacillus plantarum and Bacillus subtilis. The resulting constituent changes in dried fermented bran ingredients were also compared. Corn bran at 25 or 35 % moisture content were either ground or extruded prior to fermenting with L. plantarum or B. subtilis at 37 °C for 72 h at 200 rpm. Both the ground or extruded brans showed typical growth patterns for both probiotic bacteria studied. B. subtilis had the highest growth rate of 0.64 h−1 and lowest population doubling time of 1.09 h on corn bran (35 % moisture) extruded at 120 °C compared to no inoculation control. The major soluble sugars in corn bran were arabinose (0.011 to 1.68 g kg−1) and xylose (0.029 to 0.246 g kg−1) which decreased upon extrusion at higher temperature (HT: 140 °C). The total phenolic content range of 9–10 mg GAE g−1 for extruded and fermented brans was not significantly different from their respective controls. Phytic acid and trypsin inhibitors reduced by a maximum of 42 % and 34 %, respectively, when extruded and fermented with both microbes.