Influence of cooking methods on protein modification and in vitro digestibility of hairtail (Thichiurus lepturus) fillets

This study was designed to investigate the influence of boiling, baking, and frying on protein modification and in vitro digestibility of hairtail fillets. The boiled fillets among the three cooking methods showed lower carbonyl and NH2 content and sensory acceptance and higher digestibility, while the fried fillets showed higher carbonyl and NH2 contents and lower digestibility. The digestibility of boiled and baked fillets was less affected by cooking time. SDS-PAGE analysis showed that the protein pattern in cooked fillets was clearly affected by the cooking method. Digestibility significantly correlated with NH2 (r ≤ −0.87, p < 0.01) and carbonyls contents (r ≤ −0.85, p < 0.01); SH content significantly and negatively correlated with the digestibility from pepsin (r = −0.71, p < 0.05), but did not significantly correlate with the digestibility from pepsin and trypsin. Overall, the protein oxidation and the changes of NH2 may greatly affect the protein digestibility of cooked hairtail fillets. These results provide a deeper understanding of the effect of cooking on digestibility of fish protein.