Combined use of essential oils applied to protein base active food packaging: Study in vitro and in a food simulant

Essential oils (EOs) blends can increase the action spectrum in order to obtain more effective applications. This study aimed to optimize a blend of EOs and its incorporation into an active whey protein based film. Migration tests were performed in a fatty food simulant to verify the effectiveness of the film regarding antioxidant capacity as well as antimicrobial tests. Simplex-centroid mixture design method was used to determine the optimal EOs blend for maximizing antimicrobial and antioxidant activities (ABTS(+) assay). The combination that presented best results was composed by 51.0% of C. cassia EO, 34.0% C. zeylanicum EO, 15.0% R. officinaiis E0 and 0.0% O. basilicum EO. The EOs blend presented a high antimicrobial activity against Escherichia coil, Staphylococcus aureus and Penicillium spp. and high antioxidant activity (EC50 = 0.43 mg mL(-1)) by DPPIT assay. Whey protein film was prepared incorporating the EOs blend in different concentration levels (1, 2, 2.7 and 5%, w/w). The film with 5% (w/w) of EOs blend presented inhibition against all tested microorganisms while the film with 1, 2 and 2.7% (w/w) did not inhibit the bacteria. In the migration tests carried out with the food simulant ethanol 95% (v/v), the antioxidant capacity of the films for 10 days at 5, 20 and 40 degrees C, was not statistically significant (p > 0.05) for the same film at different temperatures, except for the control film. Besides, it was demonstrated that over 30 days the antioxidant activity of films decreased. This is an interesting application of EOs with various advantages, both for food and for Human Health.