Antioxidant activity and techno-functional properties of protein extracts from Caulerpa prolifera: Optimization of enzyme-assisted extraction by response surface methodology

In this study, ultrasound-assisted enzymatic extraction was performed to extract proteins from Caulerpa prolifera and the techno-functional properties of the protein extracts were investigated for the first time. The effect of extraction temperature (30-40 degrees C), extraction time (60-120 min) and substrate/enzyme (S/E) ratio (5-15) on protein content (PC), total phenolics content (TPC) and antioxidant activity (AOA) was investigated using response surface methodology (RSM). According to the results. optimum conditions were determined as extraction temperature of 30 degrees C, extraction time of 60.03 min and S/E of 5. The values of PC, TPC, AOA(CUPRAC) (AOA determined by cupric reducing antioxidant capacity assay) and AOA(DPPH) (AOA determined by 2,2-diphenyl-1-picrylhydrazyl assay) of the extracts obtained under optimum conditions were 51.57 g.kg(-1) dry weight (dw), 31.12 g.kg(-1) dw (expressed as gallic acid equivalents), 4.45 g.kg(-1) dw and 0.83 g.kg(-1) dw (expressed as Trolox equivalents), respectively. Water and oil absorption capacity, emulsion activity-stability and foaming capacity-stability of the proteins extracted under optimum conditions were determined as 54.0 +/- 5.0 %, 210.0 +/- 15.0 %, 41.4 +/- 2.3 %, 41.7 +/- 0.1 %, 26.5 +/- 1.5 % and 26.7 +/- 2.4 %, respectively. These research findings indicate that C. prolifera proteins, as an alternative protein source, offer promising opportunities for functional food applications.