Study on antibacterial effect of rosemary extract in combination with nisin against staphylococcus aureus in minced meat during refrigerated temperature

Synthetic preservatives have been used as food additives to extend shelf life of foods, but they are strictly regulated due to toxicological concerns and some health problems. So it is increasingly attractive to find out effective and nontoxic measures (e.g. use of natural antimicrobial agent) to delay microbial spoilage. Nisin is a bacteriocin that it is the only bacteriocin permitted for use in foods. And rosemary is one of the medicinal plants. In this study the effect of antibacterial property of various concentration of rosemary extract alone (3 and 4 mg/ml), and with nisin (7 µg/ml nisin 1.5 mg/ml RE and 8 µg/ml nisin 2 mg/ml RE) against Staphylococcus aureus in minced meat were assessed throughout 14 days of storage at 4±1˚C. Leaves and stems of rosemary after drying in the shade were soaking in pure ethanol and alcoholic extract was obtained. The minimum inhibitory concentration (MIC) of RE and nisin were determined against S. aureus using the agar dilution method. Assessment of microbial parameters (total plate count and S. aureus count) was carried out in 0, 1, 3, 7 and 14 days. The data were statistically significant (P