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 °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 metho-dology (RSM). According to the results, optimum conditions were determined as extraction temperature of 30 °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 equiva-lents), 4.45 g·kg^-1 dw and 0.83 g·kg^-1 dw (expressed as Trolox equivalents), respectively. Water and oil absorption capac-ity, 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 opportuni-ties for functional food applications.