Potential Application of Ziziphora Clinopodioides Essential Oil and Nisin as Natural Preservatives Against Bacillus Cereus and Escherichia Coli O157: H7 in Commercial Barley Soup

The aim of this study was to investigate the antibacterial activity of nisin (250 and 500 IU/mL), Ziziphora clinopodioides essential oil (0.1 and 0.2%) and their combination against Bacillus cereus and Escherichia coli O157:H7 in commercial barley soup during refrigerated storage for 9 days. Carvacrol (64.22%) and thymol (19.22%) were the major components of the essential oil. In untreated samples, the populations of E. coli O157:H7 and B. cereus were reduced the value of 2.30 and 3.95 log 10 CFU/mL, respectively, during refrigerated storage. The count of the pathogens were significantly affected ( P <0.05) by the addition of the essential oil and nisin. The lowest population of the pathogens was found in the samples treated with the essential oil at 0.2% in combination with nisin at 500 IU/mL. Our findings indicate that the essential oil of Z. clinopodioides and nisin has potential to be applied as antimicrobial and preservative agents in food products especially commercial barley soup. Practical Applications According to the results of this study, commercial barley soup can be a very suitable food by adding Ziziphora clinopodioides essential oil and nisin. In this work, Z. clinopodioides essential oil and nisin had not adverse effects on sensory properties of barley soup. Z. clinopodioides essential oil, nisin and their combination were very effective in inhibiting growth of E. coli O157:H7 and B. cereus in commercial barley soup during storage at 4C.