Barley–wheat brewers' spent grain: A potential source of antioxidant rich lipids

Brewers' spent grain (BSG), a brewery by-product, seldom finds high value applications. The present work investigated functionality of BSG oil fractions through evaluation of its 2,2-diphenyl-1-picrylhydrazyl (DPPH) quenching ability. The scavenging activity of BSG oil was 71.60% and was more than its polar, nonpolar and unsaponified fractions (61.14, 52.42, and 34.47%). The IC₅₀ of the BSG oil (7.39 µg mL⁻¹) was 1000 times lower than common antioxidants—Ascorbic acid (2.86 mg mL⁻¹) and BHT (2.60 mg mL⁻¹), establishing its superior antioxidant activity. The total phenolic content of oil was found to be 1.22 mg GAE per ml of oil while its protein content was found to be between 10.2 and 11.0 mg mL⁻¹. EPR spectroscopy showed 100% quenching of DPPH at 0.5% (w/v) of oil. GCMS revealed the presence of anti-oxidants. The accelerated oxidation study showed acceptable values for peroxide (till 6 hr) and anisidine (1 hr) tests. Practical applications: Brewer' spent grain (BSG) comprises residual constituents of the brewing process that have been utilized for low value applications. The present study revealed a number of bioactive compounds (antioxidants and phenolic compounds) and volatiles in the BSG oil. The antioxidant functionality of this phytochemical rich extract can be utilized for nutraceutical applications to reduce free radical damage in humans. For food preservation, the oil can be employed to reduce browning, rancidity and other deterioration reactions. Thus oil extracted from waste by-product can be used for high value applications.