Impact of alginate coating combined with free and nanoencapsulated Carum copticum essential oil on rainbow trout burgers

Carum copticum essential oil (CEO) is known as a valuable active food and pharmaceutical ingredient with antimicrobial and antioxidant activities. Solid lipid nanoparticles incorporated with CEO can overcome their limitations, namely low physicochemical stability and water solubility. In the current study, the antimicrobial and antioxidant activity of free and nanoencapsulated CEO were measured. The results revealed that although the nanoparticles of CEO had higher DPPH radical scavenging activity compared to free CEO, the antimicrobial activity of free CEO toward Escherichia coli and Listeria monocytogenes was higher than nanoparticles. Fish burger samples coated with free and nanoencapsulated CEO and stored for 12 days at 4°C. Alginate coating without CEO was considered as a control sample. The mean zeta potential, particle size, and polydispersity index (PDI) of nanoparticles were 19.18 ± 0.9 mV, 286.5 ± 18.2 nm, and 0.32 ± 0.01, respectively. The results revealed that lipid oxidation, microbial growth, and production of total volatile basic nitrogen in fish burger samples coated with alginate enriched with nanoencapsulated CEO were lower than free CEO. The main volatile compounds of CEO were para‐cymene, γ‐terpinene, and thymol, which were responsible for the antioxidant and antimicrobial activity of CEO. The data obtained by the current study suggest the application of alginate coating with CEO in form of nanoparticle to enhance fish burgers’ shelf life stored at 4°C.