87-10 |
Antimicrobial activity of some spice oleoresins as observed by luminometry using a cloned E.Coli strain containing the luciferase gene |
Z. Z. HAQUE1, P. Marnila2, and H. Korhonen2. (1) Department of Food Science and Technology, Mississippi State University, Box 9805, MSU, MS 38762, (2) Food Chemistry, MTT Agrifood Research Finland, FIN-31600 Jokioinen, Finland Spices such as garlic have long been recognized for their antimicrobial activity. As ethnic foods become more popular, spices and their concentrates are being increasingly used in processed foods. Our objective was to evaluate the antibacterial activity of commonly used spice extracts using a rapid dynamic method involving luminometry. Ginger, paprika, cumin, capsicum (low pungency; 500,000 Scoville units, and high pungency; 1,000,000 Scoville units), coriander, and garlic oil (soybean oil) and aqueous extracts were obtained Kalsec, Kalamazoo, MI 49005. E. Coli JM103 (LPS chemotype Re) containing the luciferase expression vector pCSS962 (luGR) and a helper plasmid pGB3 was grown in TSB and used as the test microbe. Luciferine and the E. Coli (x 109) were incubated with and without varying amounts (.05, .01, and .2%, v/v) of the spice extracts at pH 5, 6, 7 (phosphate). Since only live E. Coli expressing the luciferase enzyme illuminated, the intensity of luminescence was related to bacterial viability. After 9hrs of incubation (37o), the maximum luminescence (Max lu) of the wells were noted. All the spice extracts, particularly the oil extracts, had high antibacterial activity in the pH range (7 – 9) studied. Ginger was the best and gave readings of 0.01, 0.1 and 0 rlu, respectively at pH 5,6, and 7. Cumin gave similar though slightly lower readings. Contrary to expectations, the capsicums were significantly less effective and there was little or no effect based on the level of pungency. Data shed light on the historical reasoning for the use of these spices in tropical countries and indicate that they could be effective tools in enhancing food safety as well as palatability.
Session 87, Food Microbiology: General
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