Impact of dietary carotenoid and packaging during frozen storage on the quality of rainbow trout (Oncorhynchus mykiss) fed carotenoids.

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.

[Studies of several analytical methods for antioxidant potential evaluation in food]. / Méthodes d'évaluation du potentiel antioxydant dans les aliments.

Oxidation control is necessary to manage the evolution of complex biological system, particularly in food whose degradation could have consequences on food security. After description of context and oxidation mechanisms, several analytical methods to evaluate the additive antioxidant potential are presented. This evaluation is performed either by quantification of products (in particular hydroperoxydes) using direct or indirect photometric techniques and chemical titration with suitable reactants or on the effectiveness to trap free radicals with modelized systems that can generate them. Methods based on the comparison of radical trapping ability between an additive and Trolox (particularly Trolox(R) equivalent antioxydant capacity, TEAC) can be applied to many products whatever the hydrophily or the hydrophobia of the medium.