Effect of lactic acid bacteria fermentation on bioactive components of black rice bran (Oryza sativa L.) with different milling fractions

This study investigated the impact of fermentation using lactic acid bacteria (LAB) on the bioactive compounds and antioxidant properties of black rice bran (BRB) with varying fractions of milling. The BRB was divided into four fractions through the milling process, resulting in the outermost layer BRB-1 and the innermost layer BRB-4, and each fraction accounted for 4.14 %, 4.38 %, 3.50 %, and 3.31 % (W/W) of the whole grain, respectively. The suitable Lactobacillus plantarum for fermentation of BRB was selected from nine different LAB strains. Additionally, the changes in pH and total titratable acidity (TTA) were monitored throughout the fermentation process. Notably, the fermentation process with LAB significantly increased the total phenolic content in three milled fractions of BRB, while the total flavonoid and anthocyanin contents exhibited opposite trends. The in vitro antioxidant capacity assessment revealed that the antioxidant activity of the four fractions of BRB was enhanced by 15.94 %–98.69 % after fermentation. Additionally, the high-performance liquid chromatography (HPLC) analysis demonstrated a substantial increase in the levels of certain phenolic acids and a notable decrease in the levels of individual anthocyanins as a result of fermentation. These findings offer momentous insights regarding the potential application of fermentation techniques for enhancing the utilization of BRB.