Antibacterial activity of some Lamiaceae species against Staphylococcus aureus in yoghurt-based drink (Doogh)

Doogh is a dairy drinkable fermented product, whose shelf-life and quality is mostly affected by bacteria such as Staphylococcus spp. This study investigated the antibacterial activity of essential oils (EOs) from Thymus vulgaris L., Mentha piperita L. and Ziziphora tenuior L., alone or in combination, against Staphylococcus aureus in industrial doogh. A three-level and three-variable face centered central composite design experiment was used. Results showed that EOs significantly inhibited S. aureus growth after 1 and 7 days of storage. According to the model, the maximum inhibition was obtained in the presence of 0.2% of EO, independently of the type, and no synergistic or additive effects were observed. Slightly lower S. aureus survivals were observed at the maximum concentration of Z. tenuior EO. In spite of the antimicrobial activity of these EOs, further research is needed to assess their performance in food matrix and, in particular, in dairy product.