Properties and antimicrobial activity of silver carp (Hypophthalmichthys molitrix) skin gelatin-chitosan films incorporated with oregano essential oil for fish preservation

• Gelatin-chitosan film incorporated with OEO possessed antimicrobial activity.
• OEO could modify the properties of gelatin-chitosan film.
• Gelatin-chitosan-OEO film could extend the shelf-life of fish muscle.

Silver carp skin gelatin-chitosan films incorporated with different concentrations of oregano essential oil (OEO) were prepared and characterized. Results showed that OEO had the best antimicrobial activity among oregano, cinnamon and anise essential oil against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Bacillus enteritidis and Shigabacillus. The incorporation of OEO into gelatin-chitosan film clearly improved antimicrobial activity. As regard to the film properties, the addition of OEO into gelatin-chitosan film significantly reduced mechanical property and increased light barrier, water vapor barrier. Film solubility of gelatin-chitosan film significantly decreased when containing 4% OEO (p ≤ 0.05). The SEM result revealed gelatin-chitosan-OEO film had rough cross-section. FTIR spectra indicated that no new bonds were formed in gelatin-chitosan-OEO film. For fish preservation, total aerobic plate count and total volatile basic nitrogen values of fish muscle samples which packaged with gelatin-chitosan film incorporated with 4% OEO were significantly lower than those samples packaged with parafilm and control. These results indicated that the gelatin-chitosan film incorporated with OEO has the potential to extend the shelf-life of fish muscle.

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