Ferulic acid production from brewery spent grains, an agro-industrial waste

This research aims at the utilization of an agro-industrial waste, the brewery spent grains (BSG) for the extraction of a natural antioxidant, the ferulic acid. Brewery spent grain was initially treated with dilute sulfuric acid, and then subjected to alkaline hydrolysis using NaOH, prior to ferulic acid extraction and purification. X-ray diffraction analysis of the raw and hydrolyzed BSG showed the evidence for a possible release of phenolic extractives. The effect of extraction time (100, 120 and 140 min), temperature (60, 90, and 120 °C), and alkali concentration (1, 2 and 3% (w/v) on the ferulic acid yield was optimized by the Box Behnken Design, using Response Surface Methodology. Accordingly, the experimental ferulic acid yield obtained at optimized conditions (90 min, 120 °C and 2% (w/v) NaOH concentration) was determined to be 46.17 mg/100 g BSG. The total phenolic, flavonoid, protein and reducing sugar content of ferulic acid extract were measured. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay. Fourier Transform Infrared Spectroscopy (FT-IR) and High-Performance Liquid Chromatography (HPLC) analysis confirmed the presence of ferulic acid. Results of this present research provides an alternative insight into the waste management of BSG through ferulic acid extraction.