Rosemary essential oil microemulsions as antimicrobial and antioxidant agent in tomato paste

Abstract

The objective of this research was to evaluate the antifungal and antibacterial action of rosemary essential oil (REO) microemulsion applied in tomato paste (TP). TP is a food sensitive to degradation since several fungi and bacteria benefit from their storage conditions. Data related to the essential oil (EO) chemical composition as well as its antioxidant, antibacterial, and antifungal activity are reported. REO antioxidant analysis returned an IC50 value of 154.25 ± 3.11 mg·L −1, with the EO presenting also an interesting inhibition of growth and bactericidal characteristics for several bacteria considered, with the best results obtained for the gram-negative Escherichia coli and S. typhi (values for both of 5.19 ± 0.08 µL·mL−1 and 20.75± 0.36 µL·mL−1 for MIC and MBC, respectively). Antifungal activity was analyzed for the fungi isolated from TP containing mycelia Mucor sp., Aspergillus sp., and Penicillium sp. For all genera, at a concentration of 4.0 μg·mL−1, the inhibition halo was superior even to the antifungal Clotrimazol at a concentration of 3.0 μg·mL−1. A concentration of 1.0 wt.% of REO microemulsion applied to TP showed values of negative fields after 7 days twice as high compared to TP without the presence of EO. After 14 days, values of the negative fields continued to be higher, proving the antifungal power of REO applied to this food.