Characterization and in vitro digestibility from sargassum vulgare protein extracts and hydrolysates

In the present study, firstly, in ultrasound-assisted enzymatic extraction of proteins from Sargassum vulgare macroalgae, optimization of the extraction conditions was aimed by using response surface methodology (RSM) based on central composite design. The effects of ultrasound application time and enzyme/substrate (E/S) ratio on the protein content (PC), total phenolic content (TPC) and antioxidant activity (AOA) of were investigated. Techno-functional properties such as water absorption capacity (WAC), oil absorption capacity (OAC), emulsion stability (ES), emulsion activities (EA), foaming capacity (FC) and foaming stability (FS) of the extracts prepared under optimum conditions were determined and characterization studies were performed by SDS-PAGE, FT-IR and DSC analyses. Then, E/S and hydrolysis time were optimized during enzymatic hydrolysis of the extracts using RSM, and degree of hydrolysis (HD), TPC and AOA of hydrolysates were investigated. Protein digestibility (PD), TPC and AOA of both protein extracts and protein hydrolysates were investigated during in vitro digestion. According to the results of the study, under optimum extraction conditions (ultrasound application time: 2.50 min and E/S: 0.90), PM, TPC, AOACUPRAC and AOAABTS of S. vulgare protein extracts (SV-PE) were 247.29 mg/g, 39.41 mg GAE/g, 54.55 mg TE/g and 18.82 mg TE/g in dry weight, respectively. The WAC, OAC, FC, EA and ES of SV-PE were 89.0±0.63%, 317.0±30.0%, 12.50±0.01%, 53.36±0.84% and 3.35±0.66%, respectively. At optimum hydrolysis conditions (hydrolysis time: 300 min and E/S: 0.03), HD, TPC and AOACUPRAC values of S. vulgare protein hydrolysates (SV-PH) were 30.08%, 10.98 mg GAE/g and 2.72 mg TE/g, respectively. In chromatographic analysis of SV-PH, dominant amino acids were glutamic acid, glycine, tyrosine, leucine and lysine. In vitro gastric and intestinal digestions, PD values of SV-PE were 90.94±0.51% and 88.36±0.95%, while those of protein hydrolysates were 96.46±1.36% and 100±0.00%, respectively. In vitro gastrointestinal digestion, TPC and AOA of SV-PE decreased, while those of SV-PH increased (p<0.05). Key words: Sargassum vulgare, Macroalgae, Protein, Hydrolysate, Amino Acid, Antioxidant Activity, İn vitro Digestion.