Document Type : Research Article
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Abstract
Nisin, belonged to type-A lantibiotcs, is a well-known bacteriocin that applied as natural preservative in food productions such as milk and cheese. This peptide has an inhibitory effect on many of Gram-positive bacteria. Using of nisin alone and in combination with other hurdles may serves as an effective method to eliminate Listeria monocytogenes and other pathogens in food industries. This study was undertaken to evaluate the effect of nisin against listeria monocytogenes in different temperatures (4, 9 and 14°C), pH (5, 6 and 7) and NaCl concentrations (0, 1, 2 and 4).The minimum inhibitory concentration (MIC) of nisin was assessed using a broth micro-dilution method. Furthermore, differences in population (DP) assay was used in order to analyze the effects of (storage) temperature, pH and sodium chloride concentration on Listeria monocytogenes survival in presence of nisin. The MIC value of nisin was 320IU/ml. The effectiveness of nisin was increased at 14°C better than at 9 and 4°C (P<0.016).Nisin activity increased in the presence of 2 and 4 g/100 ml of NaCl concentration (P<0.001). Also higher inactivation was observed after to pH 5 compared to pH 6 and 7 (P<0.001). Our results demonstrated that among different NaCl, pH, temperature and nisin values, the effect of NaCl was confounded than the effect of other factors at all prepared combinations (P<0.001).Our findings suggest the application of hurdle technology for achieving effective control in most in food industries.
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