High antioxidant activity of coffee silverskin extracts obtained by the treatment of coffee silverskin with subcritical water

► Coffee silverskin (CS) is a by-product of the coffee roasting process. ► We examined antioxidant activity of CS extracts treated with subcritical water. ► The antioxidant capacities increased with increasing the extraction temperature. ► The highest antioxidant activity was observed with the extracts obtained at 270 °C. ► The protein contents in CS extracts highly correlate with the antioxidant activity.