Fermented corn bran: A by-product with improved total phenolic content and antioxidant activity

Abstract

Corn bran is a milling by-product of the corn industry; however, it has been considered a potential source of phenolic compounds. This study was conducted to evaluate the potential of solid-state fermentation with Lactobacillus reuteri and Lactobacillus plantarum for improving the phenolic compounds and antioxidant activity of corn bran. The fermentation caused a significant increase in the total phenolic content (TPC) of fermented corn brans compared to the control sample. Highest TPC was obtained after 48 h of fermentation. The antioxidant activity, measured through different methodologies (DPPH, ABTS, ORAC assays), was higher in the fermented corn bran samples than in the control one. Fermentation increased the concentration of free phenolic acids, especially ferulic acid and p-coumaric acid, in the fermented samples. Fourier-transform infrared spectroscopy indicated that fermentation promoted the degradation of some ester bonds in the substrate structure, which could lead to the release of free phenolic acids. Meanwhile, scanning electron microscopy showed that the fermentation led to the formation of a loose surface structure in the fermented samples. The results revealed that solid-state fermentation was an effective method for the enhancement of phenolic compounds, suggesting that this bioprocessing technology may help improve the antioxidant activity of fermented corn bran.