Abstract: In this study, we investigated the changes in the percentage of cooking loss, color, texture characteristics, sensory evaluation and microstructure of tilapia fillets under different boiling conditions. Meanwhile, the changes in myofibrillar protein content, total sulfhydryl content, Ca2+-ATPase activity and secondary structure were examined. The results showed that for each tested boiling temperature, the percentage of cooking loss increased to varying degrees with increasing heating time, and lower percentage of cooking loss was observed at 90 ℃ compared with the other boiling temperatures, the color parameters L* and b* increased and a* decreased compared with the fresh samples. The color of fillets remained better after undergoing high-temperature short-term boiling. The hardness, gumminess and chewiness gradually increased with increasing heating time at 50 ℃, but decreased at 60 ℃ and above. The texture properties of fish meat treated at 80 and 90 ℃ were relatively better. Scanning electron microscopy results showed that the structure of fish muscle tissue became looser after boiling, and gaps between muscle fiber bundles became observable. For each heating time, gaps between muscle fiber bundles gradually increased with increasing heating temperature, and the degree of damage became more serious. However, high-temperature short-term heating caused less damage to the structure of fish muscle tissue. The sensory evaluation results were basically consistent with the trends in all quality indicators. The myofibrillar protein content, total sulfhydryl content and Ca2+-ATPase activity decreased significantly (P < 0.05), and the degree of protein denaturation was smaller under the condition of low-temperature long-term heating. The proportion of α-helix and β-turn decreased, and the proportion of β-sheet and random coil increased. The proportion of α-helix and β-turn under the condition of low-temperature long-term heating were higher than under high-temperature short-term heating. In summary, considering the eating quality and actual production efficiency, high-temperature short-term heating is more suitable for tilapia fillets, and the quality of fillets boiled at 80–90 ℃ for 6–9 min is better.

Key words: tilapia; boiling; quality; myofibrillar protein