title: The antibacterial effect ofZiziphora clinopodioidesessential oil and nisinagainstSalmonella typhimuriumandStaphylococcus aureusin doogh, a yoghurt-based Iranian drink.
abstract: Doogh is the most popular and commonly consumed yoghurt-based Iranian drink. The aim of this study was to investigate the antibacterial effects ofZiziphora clinopodioidesessential oil (ZEO) at 0.10 and 0.20% concentrations, nisin at 250 and 500 IU mL-1, and their combination againstSalmonella typhimuriumandStaphylococcusaureusin 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-1nisin, D: 500 IU mL-1nisin, E: 0.10% ZEO + 250 IU mL-1nisin, F: 0.10% ZEO + 500 IU mL-1nisin, G: 0.20% ZEO + 250 IU mL-1nisin and H: 0.20% ZEO + 500 IU mL-1nisin. Based on gas-chromatography and mass spectrometry, carvacrol (65.22%), thymol (19.51%),p-cymene (4.86%) andɣ-terpinene (4.63%) were the major components of ZEO. The populations ofS. typhimuriumandS.aureusin samples treated with all concentrations of the ZEO and nisin were kept below 1 log CFU mL-1on day 5 of storage, while the count ofS.typhimuriumandS.aureuswas found as 2.72 ± 0.02 and 2.21 ± 0.00 log CFU mL-1on 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.
authors.affiliation: Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Razi University,  Kermanshah, Iran.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Shahbazi
keywords: Doogh; Nisin; Salmonella typhimurium; Staphylococcus aureus; Ziziphora clinopodioides