Application of Teucrium polium Essential Oil and Lactobacillus casei in Yoghurt

Food spoilage is an enormous economic problem worldwide. In this regard, new antimicrobial agents from plants and microbial source as biological additives are of significant importance. In this research, the growth and survival of Salmonella typhimurium were investigated at a 7-day interval during storage (28 days) with adding Teucrium polium essential oil (EO) (0, 80, 120 and 160 ppm) and Lactobacillus casei (108-109 Cfu/ml). The presence of bacteria was determined by culture in selective media. T. polium essential oil had the best Salmonella growth inhibition at 120 ppm and 160 ppm and in synergistic combination with L. casei. No Salmonella was isolated during the 28 days of preservation of probiotic yoghurt or probiotic yoghurt containing different concentrations of T. polium EO. However, Salmonella could be isolated in first weak storage in some treatments (including: negative control group and the groups containing T. polium EO). The results showed that combination of 80 ppm T. polium EO and L. casei decreased the required inhibitory concentration of T.polium EO.