Antibacterial activity of clove essential oil in milk against food-borne pathogenic and spoilage bacteria

Abstract

Background: In the recent years, food industry have been intensively working to replace chemical preservatives with natural, effective and nontoxic compounds which could inactivate or inhibit growth of spoilage and pathogenic microorganisms. Among natural antimicrobial agents, extracts and essential oils derived from plant and spices, in addition to contributing to the taste and flavor of food, also can reduce or eliminate a wide variety of bacterial species. Objectives: Purpose of this study was to evaluate the antibacterial effect of clove essential oil in milk against foodborne pathogenic and spoilage bacteria, which is a frequent cause of milk spoilage and food-borne infection and intoxication worldwide. Methods: Antibacterial activity of clove essential oil in milk with different content of milk fat (0.5 and 3.2% w/v) was examined by agar well diffusion method, while the influence of milk components on minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were estimated by macrodilution method. Results: The data obtained by an agar well diffusion method confirmed that milk is good medium for clove essential oil dissolution, especially milk with 0,5% milk fat, as inhibition zones were noticed for Bacillus subtilis up to 1,5% (v/v), Escherichia coli, Salmonella Enteritidis, Shigella sonnei, Listeria monocytogenes till 3,1% (v/v), while as a most resistant were Staphylococcus aureus, Bacillus cereus and Listeria innocua (6,2% v/v). Lower values for MIC and MBC were no- ticed in milk with 0,5% milk fat, which were almost three to five fold higher values from that achieved in nutrient broth, depending of bacterial species tested.