Study on antimicrobial effect aquatic extract of rosemary and nisin against Listeria monocynogenes in milk

Listeria monosytogenes is one of food borne pathogens that presence in raw foods and capable of growth during cold storage and cause infection in consumers. Raw milk is one of the most particular foods associated with listeria contamination. Reemerging listerial infection increased because of increase the consumer interest to consume of raw milk in last years. This study was conducted to evaluate the anti-listerial effect of nisin, rosemary extract and mixed of them in milk at refrigerator temperature (4±1ºC). Five treatments of milk were prepared; control sample with no nisin and rosemary extract (A), milk contain 0.5% rosemary extract (B), milk contain 1% rosemary extract (C), milk contain 1000 IU nisin (D) and milk contain 0.5% rosemary extract 500 IU nisin (E). 107 cfu/ml Listeria monosytogenes was inoculated in each sample. All samples were exanimate for Listeria monosytogenes count on day 0, 1, 2, 3, 4 and 5. Based on results; rosemary extract and nisin reduced the listerial growth. Highest anti-listerial activity was shown in sample E, D and C respectively. The antimicrobial effect of rosemary extract at high concentration significantly (p