88D-5 |
Antimicrobial activities of alliin-alliinase reaction product and methylene chloride extract of garlic |
Y. C. LEE1, D. S. Shin, C. Y. Oh, and K. S. Kim. (1) Dept. of Food Science & Technology, Chungang University, Naeri 40-1, Daeduck, Ansung City, 456-756, South Korea Antimicrobial activity is one of important physiological activities of garlic and allicin, a degradation product of alliin by alliinase, is known as the most responsible compound for the activity and strong garlic flavor. Since garlic is widely used as a spice in various foods, garlic extract or alliin-alliinase mixture with less garlic flavor could be developed as natural food preservatives. The objectives of this research were to investigate the reaction stability of alliin and alliinase and MIC(minimum inhibitory concentration) of the reaction products, and to determine MIC of methylene chloride extract of garlic under various conditions. Alliin and alliinase were extracted from garlic grown in Korea in 2000, and frozen at -70C prior to experimental uses. The alliinase activity was evaluated by the colorimetric determination of pyruvic acid produced at 420nm. Methylene chloride extract was prepared by agitating ground garlic with methylene chloride(1:5) for 4 hrs and concentrating the filterate at 40C. The extract was frozen at -70C and used for MIC determinations. MIC was determined by adding 0.1 - 6% samples to the selected microbial growth medium and monitoring O.D. at 660nm after the required incubation period. Alliinase activity was maximum at pH 6.5 and 35C, and was stable for 30 min. MIC of alliin and alliinase reaction products were 1% to B. subtilis, 2% to Listeria monocytogenes, 4% to E. coli and E. coli 0157:H7, 6% to Staphyloccocus aureus, 1% to yeast and 1-2% to fungi. Antimicrobial activities of the methylene chloride extract was 1% to the test bacteria and yeasts, and 0.5% to fungi, and was not affected by addition of starch, protein(casein) and fat(soybean oil) upto 25%. These results indicated that methylene chloride extract had more antimicrobial activities to the tested microbes than alliin and alliinase reaction products, and both were more effective to yeast and fungi. It appeared that these could be developed as natural preservatives to the selected foods.
Session 88D, Food Microbiology: General
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