A solution for fillet quality: Slaughter age's effect on protein mechanism and oxidation

Physico-chemical properties of fish flesh are reliable predictors of fillet quality and nutritional value. In our study, the age-related variations of the chemical composition, pH, water activity (aw), water holding capacity (WHC), color and texture analysis, protein thermal stability, myofibrillar fragmentation index (MFI), glycogen content, protein oxidation and protein profiles were investigated in Oncorhynchus mykiss (rainbow trout) fillet. The results revealed that protein denaturation temperatures (Tmax1 and Tmax2) decreased by 2 % and 11.6 % depending on fish age. Tmax1 and Tmax2 values in the same groups were raised 71 % at 11 months' fish and this increase was 58 % at 23 months' fish. An age-related reduction by 66.6 % and 31.25 % was noticed for protein oxidation markers sulfhydryl groups and disulfide bonds. MFI value increased by 86.6 % connected with age. The characteristics of fish meat quality are complex and are influenced by various factors that affect the degree of freshness of the product and its acceptance in the market. Taking into account the different demands of the consumer, this study has shown that age at slaughter has an impact on final product quality and that the recommended age at slaughter, taking into account market weight, positively affects meat quality.

Evaluation of different packaging methods and storage temperature on MPs abundance and fillet quality of rainbow trout

There are many studies on microplastics (MPs) about the aquatic ecosystems and its components. However, there is limited study on the MPs abundance, identification and sources in processed seafood products which are manufactured for direct human consumption. In this study, rainbow trout (Oncorhynchus mykiss) fillets were packed with different packaging techniques and stored at two different temperatures (+4 and -20°C) for 21 days. The presence, shape, size and polymer type of MPs were determined by ATR-FTIR on certain days (7, 14 and 21 days) in fillets during storage. The chemical quality changes in fillets [with pH, thiobarbituric acid reactive substrate (TBARS), and total volatile basic nitrogen (TVB-N) data] were monitored and the effect of MPs presence was evaluated. At the last step, the estimated MPs intake level in humans was determined with considering the presence of MPs (determined in fillets). The presence of MPs was determined the most in the Polystyrene plate + wrapped film (S) group and the least in the Chitosan film + Polystyrene plate + wrapped film (C) group. When evaluated in terms of chemical parameters, although good results were obtained in all samples stored at - 20°C, the presence of MPs was determined at a high level in fillets which stored at this temperature. As a result of the study, it was determined that the packaging type and storage temperature have significant effects on the presence of MPs and fillet quality.