Quality improvement of half-smooth tongue sole (Cynoglossus Semilaevis) fillets by chitosan coatings containing rosmarinic acid during storage

The effects of chitosan edible coating incorporated with rosmarinic acid on the quality of half-smooth tongue sole fillets were examined during 18 days of refrigerated storage (4 ± 0.5°C). The samples were analyzed by physicochemical, microbiological, and sensory characteristics. Results showed that samples coated with 1% chitosan containing 30 or 40 mg/L rosmarinic acid significantly lower the total volatile basic nitrogen, K value, free fatty acids, trimethylamine, total viable counts,  and H2S-producing bacteria. Low field NMR analysis (LF-NMR) results indicated that chitosan-rosmarinic acid edible coating had positive effects on maintaining the water content and water migration. These results indicated that 1% chitosan coating with 30 mg/L rosmarinic acid was a potential alternative method to improve the quality of half-smooth tongue sole fillets during refrigerated storage.