Antimicrobial activity of Curcuma longa L., Capsicum annuum L. and Piper nigrum at different conditions

Background: In addition to creating the desired flavor, spices play an important role in increasing the shelf life of food by inhibiting the growth of a variety of microorganisms. Objective: The purpose of this study was to investigate the antibacterial effect of boiled and non-boiled water extract of Curcuma longa L., Capsicum annuum L. and Piper nigrum alone or in combination. Methods: The antibacterial effect of the spices was investigated against four major food-born pathogens by agar dilution method in different acidic or salty conditions. Results: The results of this study showed that non-biled water extract of C. annuum had the highest antibacterial activity. Gram-positive bacteria were generally more susceptible to the tested spices. The antibacterial activity of the spiceces was reduced by addition of sodium chloride and in acdic pH. A synergistic effect was observed between C. annuum and P. nigrum water extracts agaist Listeria monocytogenes. Conclusion: It seems that by using mixture of spices, suitable antimicrobial preservative systems could be designed for different food products.