Comparative effect of garlic, tomato and grape extracts on shelf life and sensory evaluation of coated rainbow trout fillet (Oncorhynchus mykiss) in freezing conditions

The role of aquatic animals in human nutrition has been considered with the increasing population of the world, and it is necessary to pay attention to increasing its shelf life and changing its taste. In this project, by adding garlic, grape and tomato extracts to coated fish fillets, in order to change the taste of fish, a comparison is made to increase the shelf life in the freezer through the chemical index of total volatile bases on the base of titration, Trimethyl amine, Tiobarbitoric acid were evaluated with Spectrophotometer and also Sensory evaluation was performed in terms of smell, appearance and taste. First, the fish was filleted and washed, then the fish coating mixture was prepared by increasing the extract of garlic, tomato and garlic by 6% of weight to wheat flour, salt and sodium carbonate, and a sample was prepared as a control without extract. Then the prepared mixture was mixed with water in a ratio of 1: 1.5. The fish was immersed in this mixture and remained in this mixture for 5 minutes, then it was kept in the freezer to check the shelf life at -18 ° C and the quality changes during 6 months were examined. The amount of volatile bases respectively in the samples containing garlic, grapes and tomatoes, 21.52, 23.73, 26.5 were lower compared to the control 35.73. Trimethylamine respectively 1.114, 1.165, 1.424 compared to the control 2.508, they had lower values. Thiobarbiotric acid also respectively 0.55, 0.37 and 0.8 were close to or less than the control value.So the shelf life of the products were in garlic, grape and tomato respectively. In sensory evaluation, the highest points for taste, smell and appearance were related to garlic, tomato and grape, respectively, and this process continued during 6 months of storage in the freezer.