Structural characteristics of taste active peptides in protein hydrolysates from tilapia by-products

The aim of this study was to use different enzyme to investigate the influence of peptide characteristics and taste of protein hydrolysates from tilapia by-products. The results showed that three types of tilapia by-products were the good source of proteolysis. Flavourzyme-treated hydrolysates of three by-products obtained the highest degree of hydrolysis (skin 14.29%, head 23.7% and bone 31.86%). By sensory evaluation, strong umami, sour, and bitter tastes were found in the different protein hydrolysates. As identified by LC–MS/MS, structural proteins (actin and parvalbumin beta) and enzymes (creatine kinase and enolase) were important taste-active precursor of the potential umami peptides, while the structural proteins (myosin heavy chain, actin, and collagen) were potential sour and bitter peptides. The molecular weight of most of the three potential taste peptides was < 1500 Da and they were hydrophilic. Among the three potential taste peptides, the peptides with taste activity more than 0.5 were 46%, 45%, and 68.5%, respectively. Met was the most abundant amino acid at the terminal of the potential umami peptide, while that of potential sour and bitter taste peptides was Lys. Overall, hydrophobic amino acids at the terminal of peptide and precursor proteins are important factors to affect the taste of tilapia by-products hydrolysates.