The Effect of Bioprocessing on the Phenolic Acid Composition and Antioxidant Activity of Wheat Bran

Abstract

Cereal Chem. 91(3):255-261In the present study, bioprocessing with eight microbial strains including Bacillus species, yeasts, and filamentous fungi was evaluated for its potential to improve the phenolic acid composition and antioxidant activity of wheat bran. The soluble free and soluble conjugated fractions of ethanolic extracts of the treated bran samples were compared for their total phenolic contents, phenolic acid composition, and in vitro antioxidant activities. In general, total phenolic content in the soluble free fraction increased significantly, accounting for 241.11 ± 1.25 μg of gallic acid equivalents (GE)/g (Rhizopus oryzae), 230.50 ± 1.05 μg of GE/g (Mucor circinelloides), and 230.19 ± 1.02 μg of GE/g (Saccharomycopsis fibu-ligera). The phenolic acid composition, especially of the soluble free fraction, was improved most by S. fibuligera (hydroxybenzoic, vanillic, syringic, and trans-ferulic acids), M. circinelloides (chlorogenic acid), and R. oryzae (protocatechuic, trans-coumaric, and benzoic acids). Comparatively, bioprocessing exhibited less effectiveness on conjugated phenolic acid composition. Fermented wheat bran displayed enhanced reducing capacity, superoxide anion radical scavenging activity, and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity in comparison with the nonfermented sample. The antioxidant activity was significantly correlated to the total phenolic content.* The e-Xtra logo stands for "electronic extra" and indicates that Figure 1 appears in color online.

Solid-State Yeast Fermented Wheat and Oat Bran as A Route for Delivery of Antioxidants

“…Oat ( Avena sativa L.), even if consumed in lower quantities, has an increasing production trend (>25 million tons in 2017) [1] due to its recognition as a healthy food with high bioactive content [2]. Wheat and oat whole grains, and specifically their outer parts, are considered rich sources of phenolic compounds with significant antioxidant activity [3,4].…”

Comparison of releasing bound phenolic acids from wheat bran by fermentation of three Aspergillus species

“…Wheat bran contains a vast variety of phenolic acids, including ferulic acid, vanillic acid, coumaric acid, caffeic acid and chlorogenic acid . The effectiveness and bioavailability of these bound phenolic acids are quite limited (Zhang et al, 2014). The health benefits of phenolic acids have significant implications for the improvement of food quality, particularly through applications in functional foods and nutraceuticals (Kim et al, 2006).…”

“…Although a few reports have indicated that fermentation by Aspergillus niger can release bound phenolic acids in wheat bran, the effects of fermentation by Aspergillus oryzae and Aspergillus awamori have not yet been reported (Hegde et al, 2006;Zhang et al, 2014). Different species have different fermentation properties, which will lead to different results in the release of bound phenolic acids.…”

“…However, these phenolic acids are generally found esterified or covalently bound to cell wall polysaccharides, and are insoluble in the extraction solvents. The effectiveness and bioavailability of these bound phenolic acids are quite limited (Zhang et al, 2014). Therefore, the release of bound phenolic acids in wheat bran prior to consumption could be a strategy that improves their bioavailability and health benefits in humans.…”

“…Several postharvesting processing procedures, for example, debranning, milling, bran fractionation and grinding, can release bound phenolic acids to some extent (Zhang et al, 2014). Some more effective methods have been developed, such as acidic and alkalic hydrolysis, steam explosion, microwave-assisted extraction and ultrasound-assisted extraction.…”