Cladostephus spongiosum as a Novel Protein Source: Bioactive, Techno-Functional, and Physicochemical Properties.

Recently, the food industry has been searching for alternative proteins, and macroalgaeare one of the novel protein sources. This study aimed to determine the optimum conditions for ultrasound- and enzyme-assisted protein extraction from Cladostephus spongiosum (CS). The obtained extract was characterized by investigating techno-functional properties and some bioactive effects such as antioxidant activity (AOA) and angiotensin-converting enzyme (ACE) inhibition. Moreover, the phenolic and amino acid profile of the protein extracts (PEs) were determined, and the extracts were subjected to in vitro simulated digestion. The optimum extraction condit ions were determined by response surface methodology, where the responses were extraction yield, total phenolic content (TPC), and AOA. According to the results, the optimum conditions were ultrasound treatment time: 5.5 min, substrate/enzyme ratio: 2/1 (w/w), and extraction time: 180 min. The TPC of the PEs increased from 16.77 to 153.54 and 49.29 mg GAE/g extract in dry weight (dw) after in vitro gastric and intestinal digestion, respectively. In addition, PE of CS had 8.9 ± 0.00% ACE inhibitory activity; whereas no inhibitory activity was detected in the digested samples. The findings of this study revealed the optimum conditions for ultrasound-assisted enzymatic extraction and techno-functional and bioactive characteristics of CS PEs, and these extracts can be utilized as an ingredient to enrich protein content of a novel food product.