Revestimentos de nanoquitosana com misturas de óleos essenciais no controle de Listeria monocytogenes e Staphylococcus aureus em filés de tilápia.

Abstract

In recent decades, the fish industry has shown significant growth, driven by the incorporation of new technologies into production systems. However, fresh fish remains a highly perishable food, which demands effective preservation strategies. Among the main microbiological risks associated with this product are Listeria monocytogenes and Staphylococcus aureus, bacteria responsible for foodborne illnesses. In this context, natural preservatives, such as essential oils (EOs) and chitosan, have gained prominence due to their antimicrobial activities. However, the direct application of EOs can cause undesirable sensory changes, making nanotechnology and coatings innovative alternatives for their incorporation. Given this scenario, this study aimed to develop nanochitosan-based coatings incorporated with mixtures of oregano, coriander, and clove EOs, aiming at the control of L. monocytogenes and S. aureus in tilapia fillets. The essential oils (EOs) were chemically characterized and evaluated for phenolic compound content and antioxidant activity (phosphomolybdenum method), in addition to determining the minimum bactericidal concentrations (MBCs) against the two microorganisms. The MBCs of the EOs ranged from 0.5 to 2%, depending on the oil and the microorganism. A Central Composite Rotational Design (CCRD) was used for the mixtures with the lowest MBCs against L. monocytogenes, and these were evaluated for antimicrobial and antioxidant activity (phosphomolybdenum, β-carotene, and ABTS methods). Formulations T2 and T3, selected for exhibiting the best antioxidant and antibacterial performance, were incorporated into the nanochitosan coatings, along with a control without essential oils (T1) and another without coating (T4). Tilapia fillets were stored under refrigeration at 7 °C and analyzed at 0, 2, 4, 6, and 8 days for pH, water activity (aw), lipid oxidation (TBARS), color, and counts of L. monocytogenes and S. aureus. The results demonstrated that all 17 mixtures inhibited the growth of pathogens in vitro. Formulations T2 and T3 showed better performance in microbiological control and inhibition of lipid oxidation in the fillets. Thus, it is concluded that the developed coatings represent a promising alternative for application in the fish industry, contributing to microbiological safety and product quality. Future studies recommend conducting sensory analyses to evaluate consumer acceptance of tilapia fillets.