Effect of diets containing Celmanax prebiotic on fillet quality of Oncorhynchus mykiss during refrigerated storage

This study aimed to evaluate the fillet quality of rainbow trout, Oncorhynchus mykiss after feeding with different levels of Celmanax prebiotic. A total of 780 trout with an initial body weight of 18 ± 2 g were randomly distributed after adaptation to the experiment environment in tanks filled with 105 L spring water (65 fish per tank). Three experimental groups and control each with three replicates were considered. Trout were fed with diets containing 2 (T2), 4 (T4) and 6 (T6) g/kg prebiotic for eight weeks. Then, the fish were filleted and maintained in the refrigerator. The chemical parameters including TVB-N, PV, TBA, FFA, TVC and PTC were estimated in 0, 3, 6, 9, and 12 days of storage time. No significant differences were observed in experimental groups and control in free fatty acids content in fillet (p>0.05). The amounts of peroxide and thiobarbituric acid in experimental groups were lower than control. The amount of TVB-N increased in experimental groups compared to control. The total viable count and psychrophilic count of bacteria in the control group were higher than the experimental groups (p<0.05). The lowest counts of bacteria belonged to T6 (p<0.05). This study showed that the increased levels of Celmanax prebiotic in trout diet could increase shelf-life of fillet in the refrigerator

Effect of different cooking processes on the fatty acid profile of grass carp (Ctenopharyngodon idella) fillets during chill storage

The effects of different cooking methods (deep fat frying, boiling and steaming) on lipid content and fatty acid composition of grass carp (Ctenopharyngodon idella) fillets during chill storage were investigated. Fillet samples were cooked and then stored at + 4°C for 4 days. The control and the cooked fillet samples were analyzed for their chemical characteristics. Twelve fatty acids were identified with 39.11, 15.37 and 45.52 g/ 100 g of saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) respectively. The n-3/n-6 ratios of raw, deep fried, boiled and steamed samples were 1.12, 0.10, 1.45 and 0.72, respectively. The patterns of changes in fatty acid groups was different in fried, boiled and steamed samples after 1 and 4 days of chill storage. The EPA+DHA/C:16 ratio was higher in boiled and boiled- chill stored samples than steamed and fried samples. EPA+DHA/C:16 ratio for cooked, stored for 1 day and then 4 days were as 0.051, 0.003 and 0.017 for fried, 0.492, 0.583 and 0.489 for boiled and 0.247, 0.037 and 0.149 for steamed samples, respectively. These results showed that the boiled process is better than other cooking processes on the FA pattern of grass cap

Contribution à l'étude des procédés combinés de congélation - décongélation sur la qualité du saumon (Salmo salar) (impact des procédés haute pression et conventionnels)

Ce travail concerne l étude de l effet de différents procédés combinés de congélation et de décongélation sur la qualité de la chaire de saumon. En effet, il est connu que la formation des cristaux de glace induit une action mécanique et également biochimique (effet dénaturant par cryoconcentration) sur les tissus biologiques. Le saumon (Salmo salar) a été considéré comme produit d étude. Différents procédés de congélation (par air, par contact, par haute pression) et de décongélation (par air, par immersion, par haute pression) ont été mis en œuvre et optimisés. Il ressort que la congélation par haute pression conduit à une dénaturation partielle des protéines qui se répercute par une augmentation de la fermeté. Parallèlement, le procédé de congélation haute pression conduit à une perte par exsudation minimisée lors de la phase de cuisson. Un changement important de couleur observé après la chaîne de procédés (congélation-décongélation) et est surtout lié au procédé haute pression. Il ressort des résultats que la congélation par haute pression offre une alternative intéressante par rapport à la congélation par air pulsé. L ensemble de ce travail a permis de mettre en évidence l effet des combinaisons de différents procédés et trouve son intérêt pour l optimisation de procédés industriels mis en œuvre pour la préparation de plats cuisinés par exemple.This work relates to the study of the effect of different combined processes of freezing and thawing on the quality of fish. Indeed, it is known that the formation of ice crystals induces a mechanical and also biochemical action (denaturation effect by cryoconcentration) on biological tissue. The salmon (salmo salar) was considered for this work. Different processes of freezing (blast air, contact, high pressure) and thawing (blast air, immersion, high pressure) were set up and optimised. The high pressure freezing leads to a partial denaturation of the proteins, which is evidenced by an increase in toughness. The high pressure freezing process leads to minimized drip loss during the cooking process. An important change in colour observed after the combined processes (freezing, thawing) and is mainly related to the use of high pressure. The results showed that high pressure freezing offers an interesting alternative in comparison to blast air freezing. This work permitted to demonstrate the effect of the different combinations of processes and can find its interest in the optimisation of industrial processes implemented for the preparation of cooked dishes for exampleNANTES-BU Sciences (441092104) / SudocNANTES-Ecole Centrale (441092306) / SudocNANTES-BU Technologie (441092105) / SudocSudocFranceF