Effects of Carboxymethyl Chitosan/Pectin Coating Containing Free and Nanoliposome Essential Oil on the Shelf Life of Shrimp During Ice Storage.

The aim of this study is the estimation of the influence of carboxymethyl chitosan (CMCS)/pectin coating containing essential oil (MP EO) nanoliposomes (NLs) on melanosis, sensory analysis, bacterial counts, physicochemical properties, and color analysis of shrimp during iced storage. In addition, the impact of MP EO on the shrimp's polyphenol oxidase (PPO) enzyme inhibition at different concentrations was measured. For this aim, the treated fillets were divided including (1) control, (2) sodium metabisulfite (SMS), (3) MP EO coating, (4) MP EO NLs, (5) MP EO-CMCS/pectin, and (6) MP EO NLs-CMCS/pectin coating. Two percentage of MP EO indicated the maximum inhibitory effect of PPO enzyme after 1 and 3 min with values of 75% and 64%, respectively. At the end of storage, the highest and lowest total mesophilic bacteria (TMB) and total psychrotrophic bacteria (TPB) counts were related to control (10.88 and 8.25 log CFU/g) and MP EO NLs-CMCS/pectin coating (6.87 and 6.90 log CFU/g), respectively. The coated shrimp improved the physicochemical properties (such as total volatile bases-nitrogen [TVB-N], pH, peroxide value [POV], and thiobarbituric acid [TBA]) during storage on ice. The lowest rate of TVB-N (30.33 mg/N100g) and pH (7.06) was recorded in shrimp coated with MP EO NLs-CMCS/pectin on day 12. During storage for 12 days, the MP EO NLs were better than the other treatments in reducing the rate of oxidation of lipids of shrimp (POV [2.12 meq peroxide/1000 g lipid] and TBA [3.02 mg MDA/kg]). Moreover, shrimp treated with MP EO NLs-CMCS/pectin had higher odor, texture, color, and overall acceptability scores, compared to the others, after the storage of 12 days at 0°C. Overall, these findings suggest that MP EO NLs-CMCS/pectin-based nanocomposite coating could be utilized as an alternative packaging method in seafood products with notable antioxidant, antibacterial, and nutritional properties.