The antibacterial effect of Ziziphora clinopodioides essential oil and nisin against Salmonella typhimurium and Staphylococcus aureus in doogh, a yoghurt-based Iranian drink

Doogh is the most popular and commonly consumed yoghurt-based Iranian drink. The aim of this study was to investigate the antibacterial effects of Ziziphora clinopodioides essential oil (ZEO) at 0.10 and 0.20% concentrations, nisin at 250 and 500 IU mL-1, and their combination against Salmonella typhimurium and Staphylococcusaureus in doogh during storage at 4 ˚C for 9 days. Nine batches were studied as follows: control: no ZEO or nisin added, A: 0.10% ZEO, B: 0.20% ZEO, C: 250 IU mL-1 nisin, D: 500 IU mL-1 nisin, E: 0.10% ZEO + 250 IU mL-1 nisin, F: 0.10% ZEO + 500 IU mL-1 nisin, G: 0.20% ZEO + 250 IU mL-1 nisin and H: 0.20% ZEO + 500 IU mL-1 nisin. Based on gas-chromatography and mass spectrometry, carvacrol (65.22%), thymol (19.51%), p-cymene (4.86%) and ɣ-terpinene (4.63%) were the major components of ZEO. The populations of S. typhimurium and S.aureus in samples treated with all concentrations of the ZEO and nisin were kept below 1 log CFU mL-1 on day 5 of storage, while the count of S. typhimurium and S.aureus was found as 2.72 ± 0.02 and 2.21 ± 0.00 log CFU mL-1 on day 5 for untreated samples, respectively. The ZEO separately and in combination with nisin, was very effective against these two common food-borne pathogens. The ZEO alone and in combination with nisin could be considered as a potential strong antimicrobial agent that can be used for the growth inhibition of aforementioned bacteria in food products especially doogh.

The antibacterial effect of Ziziphora clinopodioides essential oil and nisin against Salmonella typhimurium and Staphylococcus aureus in doogh, a yoghurt-based Iranian drink Keywords:

Doogh , nisin , Salmonella typhimurium , Staphylococcus aureus , Ziziphora clinopodioides