the effect of chitosan edible coating with cinnamon and thyme essential on physicochemical and sensorial properties freshwater crayfish at refrigerator temperture

The aim of this study was to investigate the effects of three chitosan variables with concentrations of (5.5, 1.0, 1.2%) and thyme essential oil (0.5-1%) and cinnamon essential oil (0.5-1%) on freshwater crabs after 7 days of storage at 4°c in a refrigerator. chitosan solutions were prepared in 1% acetic acid solution and mixed with 3% bovine gelatin solution at 40°c. after homogenizing the bovine gelatin and chitosan solutions at a ratio of 30 to 70 at 45°c, and finally thyme and cinnamon essential oil at concentrations of 0.5 and 1% were added to the prepared solution. all tests were performed in triplicate in a significant factorial experiment based on a completely randomized design. analysis and evaluation (anova) was performed using spss 21 statistical software at a probability level of 5% (p < 0.05) and duncan s multiple range test with a significant factorial at a probability level of 5% to confirm the existence of a difference between the means. the combination of 1% chitosan and 1% thyme and cinnamon essential oil mixture had a significant effect on quality retention (p < 0.05). the combination of 1% chitosan coating and 3% gelatin with 1% thyme and cinnamon essential oil maintained the weight of freshwater crabs during shelf life and, as a result, had a significant effect (p < 0.05) in preventing weight loss. the least weight loss was related to the treatments of 1% chitosan and 1% thyme and cinnamon mixture. also, the highest moisture and the best sensory analysis were related to this percentage concentration of edible coating.