Antimicrobial effect of Thymus vulgaris and Rosmarinus officinalis L.essential oils against Gram-positive bacteria inoculated in cooked turkey breasts stored under different temperatures

In order to simulate post-cooking contamination, the study evaluated the effects of storage temperature on the antibacterial activity of essential oils (EOs) of Rosmarinus officinalis L. (0.6%) and Thymus vulgaris (0.3%) added to cooked turkey breasts inoculated with Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 14579), and Listeria innocua (ATCC 33090). The turkey breasts were packaged aerobically and stored at 3 ± 1 °C for 120 h, 8 ± 1 °C for 120 h, and 3 ± 1 °C for 24 h, followed by 12 h at 25 ± 1 °C, and at 3 ± 1 °C until the end of storage (120 h). Sensory assessments and microbial analysis were performed at 0, 24, 36, 72, and 120 h of storage. A gas chromatography-mass spectrometry was used to analyse the components of the EOs; the major components in rosemary EO were 1,8-cineole (40.99%), α-pinene (13.40%), and campohr (10.92), while thyme EO was dominated by thymol (35.72%), o-cymene (20.65%), and γ-terpinene (8.81%). Thyme EO application led to a significant (P < 0.05) reduction of bacterial growth at each day of testing and was unaffected by abused storage temperature, while rosemary EO, when used at 0.6%, was found to be effective against L. innocua cells during regular and inadequate storage (3 ± 1 °C and 8 ± 1 °C). According to sensory analysis, samples containing thyme and rosemary EO received better scores than the control. These results demonstrate that thyme and rosemary EOs have significant antibacterial activity and can be recommended as a preservative except for post-contamination.