Biological evaluation and application of essential oils in active packaging as antioxidants in salami

Abstract

The objectives of this work were to extract and determine the chemical composition of essential oils (EOs) from Thymus vulgaris, Salvia officinalis and Ocimum basilicum, evaluate the antibacterial activity of these EOs on Salmonella choleraesuis and Listeria monocytogenes, evaluate antioxidant activity by free radical scavenging methods DPPH and β-carotene bleaching, evaluate the insecticidal activity on the Drosophila suzukii fly, produce emulsions with thyme essential oil using two surfactants Tween 80 and Pluronic F127 and incorporate them into pectin films. The antioxidant capacity of the films was also studied as a potential active packaging applied to control lipid oxidation of sliced salami. The EOs were extracted by hydrodistillation and characterized by gas chromatography coupled to a mass spectrometer. Thyme essential oil emulsions were produced using mechanical stirring and ultrasonic tip sonication and characterized using particle size and zeta potential. The pectin films were produced by casting and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The antioxidant activity of the films was evaluated using the DPPH radical stabilization test. The color parameters and volatile compounds of sliced salami were evaluated during 14 days of storage at 7 oC. The major compounds present in the EOs of T. vulgaris, S. officinalis and O. basilicum were thymol (62.67%), ρ-cymene (22.83%) and carvacrol (4.64%); camphor (63.37%), β-pinene (11.73%), and 1,8-cineole (10.21); and (E)-anethole (33.06%), linalool (27.70%) and 1,8-cineole (12.69), respectively. The EO from T. vulgaris was the one with the highest antioxidant activity compared to the two methodologies tested and the highest antibacterial activity against both bacteria, and this EO was used for the production of emulsions. Particle size analysis showed that all emulsions produced were nanoemulsions and the zeta potential was shown to be stable. The electron micrographs showed the presence of micropores, indicating the incorporation of nanoemulsions containing T. vulgaris essential oil into the pectin films. The efficiency of incorporation of EO-containing nanoemulsions into pectin films was evidenced and confirmed by FTIR and TGA results and the antioxidant activity of the films was proven. Pectin films incorporated with T. vulgaris essential oil nanoemulsions, regardless of the surfactant used, provided lower production of aldehydes, especially hexanal and nonal, related to lipid oxidation. The results indicated that pectin films incorporated with T. vulgaris EO nanoemulsions, under study, may be promising and applied as active films in foods to control lipid oxidation, preserving the quality, as well as increasing the shelf life of meat products.