Optimization of chitosan and / or gelatin edible coatings to improve quality of refrigerated shrimp

In order to improve the quality of shrimp (Litopenaeus vannamei) at refrigerated temperature (4±1°C), the shrimp samples were coated with solutions of chitosan (0, 0.5, 1, 1.5 and 2%), gelatin (0, 2 and 3%) and combination of them in 15 treatment group.Preservative effect of the coatings was evaluated by biochemical analyses, microbiological assays and physical measurements over 8th day of storage time. The findings indicated that 1%chitosan and 3%gelatin based coating was superior to others in preservation spoilage, inhibiting oxidation, improvement physical properties. The coating significantly (p≤0.05) reduced chemical spoilage as reflected in pH and total volatile basic nitrogen, microbial growth as reflected in total and psychrotrophic bacterial count and lipid oxidation as displayed in peroxide value and thiobarbituric acid compared to other treatment. Also, coated shrimps with the optimized coating were significantly (p≤0.05) indicated improvement in weight loss, color as reflected in a*, b* and L* values and texture as reflected in hardness compared to others. The optimized coating could enhance the shelf life of shrimp under refrigerated storage.