Original article: Thermal pretreatment and chemical modifications as a means to alter hydrolytic characteristics and prevent bitterness in hydrolysates of fishery by‐catch (Decapterus maruadsi) protein

In this study, fishery by‐catch protein (Decapterus maruadsi) was first thermal treated (60–100 °C), phosphorylated (0.5–4.0 g g^?1 protein) or succinylated (0.05–0.3 g g^?1 protein) before hydrolysis to prevent the bitterness of the resulting hydrolysate. Hydrolysis was performed at 50 °C, 10 h, pH 8.0 by Alcalase. Results showed that thermal treatment upon 80 °C, succinylation and phosphorylation resulted in significant decrease in amino acid content and increase in larger peptide content (>1450 Da). Succinylation did not reduce the bitterness as a result of higher content of small peptides (<550 Da), which was found to be correlated positively with the bitterness of hydrolysates. However, thermal treatment, especially phosphorylation, could reduce the bitterness to discernible level, indicating that phosphorylation before hydrolysis could be a potential means to prevent the evolution of bitter flavour which restricts the practical uses of the hydrolysates.