Assessment of Lipase Inhibition Activity of Whiteleg Shrimp (Litopenaeus vannamei) Head Protein Hydrolysate

This study investigated lipase inhibition activity (a new bioactivity relating to managing diseases of obesity) of whiteleg shrimp (Litopenaeus vannamei) head (WLSH) protein hydrolysate and its peptide fractions, contributing to enhance value for the shrimp processing by-product. Firstly, single-factor tests were performed to select appropriate levels for three hydrolysis parameters, encompassing WLSH powder-to-water ratio, enzyme-to-substrate (E:S) ratio and hydrolysis time. The best hydrolysis condition included a WLSH powder-to-water ratio of 1:5 (w/v), an E:S ratio of 40 U/g protein, and a hydrolysis time of 4 h, yielding the protein hydrolysate with the highest lipase inhibition activity of 31.60 ± 0.58%. Notably, the hydrolysate retained over 93% its native activity after pH (1–9) or heat (100 °C, 30 min) treatment. Moreover, it was rich in essential amino acids, comprising 39.95% of its total amino acid content. In addition, the hydrolysate was fractionated using ultrafiltration with sequential molecular weight cutoffs of 30, 10, 3 and 1 kDa. This process yielded the < 1 kDa peptide fraction with elevated lipase inhibition activity (33.67 ± 0.28%). These findings could be beneficial for the application of the WLSH hydrolysate and its < 1 kDa peptide fraction in the development of functional foods or nutraceuticals.