Shelf-life extension of chilled olive flounder (Paralichthys olivaceus ) using chitosan coatings containing clove oil

This work aims to evaluate the effects of clove oil combined with a chitosan coating on the quality and shelf-life of refrigerated flounder using microbiological, physicochemical, and sensory assessments. The effects of the chitosan (Ch) coating combined with clove oil (Ch + CO) on the quality of olive flounder were examined during 15 days of chilled storage. The microbiological, physicochemical, and sensory attributes of the olive flounder were determined. The growth of microbes on the olive flounder was most rapid in the control samples, followed by growth on the Ch coating, and was least on the Ch + CO coating. Bacterial counts of Pseudomonas spp., lactic acid bacteria, Enterobacteriaceae and H2S-producing bacteria were significantly lower than that in the samples coated with Ch + CO. The TBA values of all of the samples were lower than 0.4 mg/100 g during storage, and the lowest TBA value of the flounder coatings was obtained with the Ch + CO coating. The total volatile basic nitrogen (TVB-N) and K values for all of the samples increased during storage, but the increases were significantly less rapid in the samples coated with Ch and Ch + CO. Interestingly, the TVB-N and K values were well correlated with the microbiological data, indicating that the TVB-N and K values could serve as useful indices for evaluating fish freshness. The results indicated that the Ch + CO coating extended the shelf-life of the fish by 6 days. Practical application Applications of edible chitosan-based coatings may be useful in prolonging the shelf-life of fish and meat because these coatings provide a barrier against moisture, moisture transfer, and oxygen penetration. Clove oil is an essential oil that is mainly composed of eugenol, beta-caryophyllene, alpha-humulene, and eugenyl acetate, and has analgesic, anti-inflammatory, and antimicrobial properties. The development of targeted antioxidant and antimicrobial natural food coatings to prolong the shelf-life of fish is desirable. Thus, this work aims to evaluate the effects of clove oil combined with a chitosan coating on the quality and shelf-life of refrigerated flounder by microbiological, physicochemical, and sensory assessments.