Comparative effect of a previous 150-MPa treatment on the quality loss of frozen hake stored at different temperatures.

BACKGROUND

This study addresses the quality loss of European hake (Merluccius merluccius) during frozen storage. Its objective was to comparatively analyse the effect of a previous high-pressure processing (HPP) (150 MPa for 2 min) when different storage temperatures (-10, -18 and -30 °C) were employed.

RESULTS

Most chemical quality indices (trimethylamine, TMA; dimethylamine, DMA, formaldehyde, FA; free fatty acids, FFAs) provided a marked content increase with freezing and frozen storage time, values being higher by increasing the storage temperature. Previous HPP led to an inhibitory (P < 0.05) effect on the TMA, DMA, FA and FFA formation in frozen fish kept at -10 and -18 °C, the preservative effect being higher at the highest temperature tested; however, in agreement to the low damage development, no effect could be proved on samples stored at -30 °C. Concerning lipid oxidation, peroxides formation was found low, although a slight increasing effect (P < 0.05) was implied in fish corresponding to all temperatures as a result of the previous HPP; furthermore, an inhibitory effect (P < 0.05) on fluorescent compounds formation (tertiary lipid oxidation) was evident after freezing and at month 9 for -10 °C samples.

CONCLUSION

It is concluded that a 150-MPa high-pressure treatment may inhibit the formation of degradative molecules such as DMA, FA, TMA and FFAs during the frozen storage at -18 °C (maximum recommended) and -10 °C. However, results have indicated that lowering the storage temperature showed to be more effective than the current HPP (150 MPa for 2 min). © 2020 Society of Chemical Industry.