Dados do Trabalho

Título

Development of alginate-based coatings incorporated with oregano essential oil nanoemulsions for application to fish fillets

Introdução

Oregano essential oil has important antioxidant and antimicrobial properties, which makes it a target for applications aimed at increasing shelf life and inhibiting bacterial growth. In the form of nanoemulsions, oils can have their compounds protected and their properties improved. In this context, the objective of this study was to produce alginate-based coatings incorporated with oregano essential oil nanoemulsions (ONE) and evaluate the effect of their application on the microbiological safety of fish.

Material e Métodos

ONE was prepared by mixing oregano essential oil(2 or 4% v/v) and lecithin (20% m/m oil content), followed by the addition of Tween 80 (2 or 4% v/v) in Ultra-Turrax (10,000 rpm/5 min). This emulsion was subjected to ultrasonic treatment (150 W/3 minutes). The coating-forming solution was formed with the addition of ONE to a 1% (m/v) sodium alginate solution. The droplet size, polydispersity index (PDI), Zeta potential and antimicrobial activity against Salmonella Enteritidis ATCC 13076 and Escherichia coli ATCC 11229 were evaluated for the nanoemulsions. The microbiological and physical-chemical quality of tilapia fillets was evaluated for 7 days, after the application of ONE and the coatings.

Resultados e Discussão

Fillets without treatment were used as control. ONE2% and ONE4% presented: 132 ± 7 nm and 155 ±1 nm; 0.2 ± 0.01 and 0.2 ±0.01; -28.9 ±0.8 mV and -32.4 ±0.6 mV for droplet size, PDI and Zeta potential, respectively. These values suggest that emulsions were stable, since nanoemulsions < 200nm, with PDI < 0.6 and Zeta potential close to ± 30 mV are less prone to destabilization phenomena. None of the nanoemulsions was able to inhibit the growth of S. Enteritidis. On the other hand, they all inhibited the growth of E. coli. The microbiological analysis of the fillets revealed that only ONE 2% and the coating with ONE2% showed less bacterial growth. Physicochemical analyzes revealed that all fillets remained fresh and without changes in color.

Conclusão

Therefore, it can be concluded that the application of ONE2% and the coating containing ONE2% showed slight improvements in the physical-chemical and biological quality of the fillets. However, future studies including new essential oils in varying concentrations may provide even more promising results.