Effects of different thawing methods on microstructure and the biochemical properties of tilapia (Oreochromis niloticus) fillets during frozen storage.

This study investigated the effects of different thawing methods (water immersion thawing [WIT, 25 °C], air thawing [AT, 25 °C] and refrigerator thawing [RT, 25 °C]) on the biochemical properties and microstructure of tilapia (Oreochromis niloticus) fillets during storage at −18 °C for 6 months. The results indicated that the thawing time for WIT, AT and RT were approximately 7, 83 and 616 min, respectively. Thawing and cooking losses in the RT samples were significantly lower than those in WIT and AT samples (P < 0.05). The microstructural integrity of RT samples was less compromised than that of WIT and AT treated samples. Ca2+‐ATPase activity and SH content decreased with increasing storage time and the frozen storage time. Compared with the other two thawing groups during frozen storage, RT had the highest fluorescence, which was significant for the quality of tilapia fillets. However, no significant difference (P < 0.05) was observed in protein secondary structure changes, especially β‐sheets and β‐turns. Therefore, RT is suggested to be an effective thawing method to minimise quality change during frozen storage and the frozen storage time has a greater impact on its quality. These results demonstrate the interaction between frozen storage and thawing processes on selected quality parameters. [ABSTRACT FROM AUTHOR]