Effects of multiple freezing and refrigerator thawing cycles on the quality changes of sea bass (Dicentrarchus labrax)

The freezing-thawing effect on the meat quality of whole, gutted and fillets of sea bass (Dicentrarchus labrax) were investigated. It was aimed to investigate the changes in the meat quality of whole, gutted and fillets of sea bass in multiple frozen (-18±2ºC) and thawed cycles in refrigerated conditions (4±2°C). The meat quality assessment of the sea bass groups (whole, gutted and fillets) subjected to multiple freeze and thaw cycles was performed by monitoring sensory quality, chemical analysis such as pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), thiobarbituric acid (TBA), crude protein and lipid content. The length of the thawing process caused quality changes such as dryness of the skin and undesirable odor formation. Thus the sea bass groups reached unacceptable levels after the 5th freeze/thaw process. According to the sensorial evaluation, no significant differences (P>0.05) were found in general acceptability values among the sea bass groups thawed under refrigerator conditions, but there was a significant difference in pH, TVB-N, TBA and crude protein (P<0.05) results. Significant differences (P<0.05) in TMA-N concentrations and crude fat were observed between the whole and gutted samples and also between the whole and fillet samples.