Physicochemical properties and angiotensin-I converting enzyme inhibitory activity of lipid-free ribbon fish (

The study aims at removal of lipid from ribbon fish protein hydrolysate (FPH) to enhance the protein content and analyse its physicochemical and bioactive properties. Ribbon fish protein hydrolysate was prepared using commercially available papain enzyme (1.5% w/v for 4 h). The resulting supernatant was further treated with lipase (0.5-2.0% w/v for 1-5 h). The treatment used in this study reduced ~ 98% of lipids depending on the enzyme concentration, temperature, pH, and duration of the treatment. Lipase treatment for 2 h increased the protein content from 62.87 to 94.11%. FPH after lipase treatment showed 1.21 folds increase in angiotensin-converting enzyme-I (ACE-I) inhibitory activity and 1.7 folds increase in standard amino acids composition (32.193 to 61.493 g/100 g). The physicochemical properties of FPH samples were analyzed by solubility, hygroscopicity, color, FT-IR, SEM, SDS-PAGE, and Zeta Potential. Use of lipase enzyme for separating the lipid content from protein hydrolysate without conferring any undesirable adverse effects on the physicochemical properties of protein hydrolysate. Lipid-free protein hydrolysates can be of commercial importance for their enhanced ACE-I inhibitory activity, replacing the side effect causing synthetic drugs for hypertension, and can have potential applications in developing functional food formulations. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05620-z.