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Abstract
Cobia (Rachycentron canadum) is an oily fish species that is highly perishable during cold storage. To extend the shelf life of fish fillets without compromising quality, the use of natural preservatives with antioxidant and antimicrobial properties has received considerable attention. Kombucha (Kb), a fermented tea product, and Chitosan (CS), derived from the chitinous shells of shrimp, are both natural substances with demonstrated antioxidant and antimicrobial capabilities.A comparative experiment was conducted to examine the characteristics of CS, Kb, and Kb - CS solutions. The results showed that the Kb - CS solution exhibited superior antioxidant activity and enhanced capability against E. coli and S. aureus compared to the individual Kb or CS solutions.Cobia fillets were subjected to dipping in Kb - CS 1.0%, CS 1.0%, Kb solutions, and a control sample (C), and subsequently stored under refrigeration for 10 days. The results indicated that the fillets coated with Kb - CS 1.0% demonstrated the highest water-holding capacity and elasticity, and the lowest peroxide value (PV) among the tested samples. Furthermore, the total viable count (TVC) was reduced by more than 3.0log(CFU/mL) compared to the control.An investigation was then conducted to assess the effect of varying CS concentrations (CS 0.5%, CS 1.0%, CS 1.5%, CS 2.0%) within the Kb - CS coating solution on fish quality after 0, 3, 6, 9, 12, and 15 days of storage. The parameters measured included the elasticity and water-holding capacity of the fish fillets, the total viable count and Coliforms density, and the sensory evaluation of fish freshness.The findings revealed that cobia fillets dipped in the Kb - CS 1.5% solution maintained muscle elasticity and water-holding capa4444city, while the PV remained virtually unchanged during 12 days of storage. The total viable count increased by only 1.0log(CFU/g) compared to the initial count after 15 days of storage. Quality Index Method (QIM) sensory evaluation also confirmed that the Kb-CS 1.5% -coated fish exhibited the slowest rate of freshness deterioration compared to the other tested samples.
Keywords: Cobia (Rachycentron canadum), cold storage, Kombucha – Chitosan solution