BACKGROUND: The storage life of frozen salmonids is often limited primarily by oxidation and flesh discolouration due to carotenoid degradation. The objective of this research was to determine the carotenoid changes and therefore the muscle colour modifications during 6 months of frozen storage (-18 °C) of whole rainbow trout fed astaxanthin (100 ppm) or canthaxanthin (80 ppm), kept under two different packagings: plastic film and cardboard box. RESULTS: After 6 months of frozen storage, the carotenoid type effect was seen for dry matter while there was no packaging material effect on carotenoid, total lipids, and TBARS contents of trout fillets. The time under frozen storage had an effect on carotenoid and TBARS fillet concentration. The carotenoid-type effect was noted for the four colour parameters (lightness difference, chroma difference, hue angle difference, and total colour difference) of rainbow trout fillet, while the packaging material effect was observed only for chroma. Frozen storage time had an effect on the four colour parameters of rainbow trout fillet. CONCLUSION: Carotenoid and packaging material effects were more marked for colour parameters than for biochemical parameters. In this study, as fish were frozen and stored as whole fish, fish skin provided good protection against oxidation.
BACKGROUND: The storage life of frozen salmonids is often limited primarily by oxidation and flesh discolouration due to carotenoid degradation. The objective of this research was to determine the carotenoid changes and therefore the muscle colour modifications during 6 months of frozen storage (-18 °C) of whole rainbow trout fed astaxanthin (100 ppm) or canthaxanthin (80 ppm), kept under two different packagings: plastic film and cardboard box. RESULTS: After 6 months of frozen storage, the carotenoid type effect was seen for dry matter while there was no packaging material effect on carotenoid, total lipids, and TBARS contents of trout fillets. The time under frozen storage had an effect on carotenoid and TBARS fillet concentration. The carotenoid-type effect was noted for the four colour parameters (lightness difference, chroma difference, hue angle difference, and total colour difference) of rainbow trout fillet, while the packaging material effect was observed only for chroma. Frozen storage time had an effect on the four colour parameters of rainbow trout fillet. CONCLUSION:Carotenoid and packaging material effects were more marked for colour parameters than for biochemical parameters. In this study, as fish were frozen and stored as whole fish, fish skin provided good protection against oxidation.