Ultrasound‐assisted enzymatic extraction of proteins from Gracilaria dura : Investigation of antioxidant activity and techno‐functional properties

Abstract

In this study, ultrasound-assisted enzymatic extraction was performed to extract proteins from Gracilaria dura for the first time. The ultrasonic applying time (30-300 sec), enzyme/substrate (E/S, 0.5-2.5) and extraction time (20-28 h) on protein content (PC), total phenolic content (TPC) and antioxidant activity (AOA) was optimized using response surface methodology. Techno-functional properties of protein extracts obtained under optimum conditions were determined. At optimum conditions (ultrasonic applying time:257.57 sec, E/S:2.5, extraction time:22.61 h), PC, TPC, AOACUPRAC and AOAABTS were found as 189.59 mg/g, 60.52 mg GAE/g and 55.66 mg TE/g and 478.50 mg TE/g dw, respectively. The water/oil absorption capacity, foaming capacity/stability, emulsifying activity/stability of the protein extracts were 195±0.08%, 568±0.10%, 12.5±0.00%, 0%, 44±0.00% and 75±2.50%, respectively. In conclusion, Gracilaria dura protein extracts may have an important potential to improve antioxidant activity and functional properties of various food products due to high antioxidant activity and good level of water/oil absorption capacity.