29F-17

H. J. CHUNG, Food Science and Technology, Chonnam National University, Kwang-Ju City, S. H. Choi, Food Science & Technology, Chonnam National University, 300 Yongbong-Dong, Buk-Gu, College of Agric. and Life science, Gwangju, South Korea, P. M. Davidson, Dept. of Food Science & Technology, Univ. of Tennessee, 2509 River Dr., 201 Mcleod Food Tech Bldg., Knoxville, TN 37996-4539, E. S. Ahn, Foods and Nutrition, 300 Yongbong-Dong, Buk-Gu, College of Agric. and Life science, Gwangju, South Korea, and S. H. Kang, Foods and Nutrition, Chonnam National University, 300 Yongbong-Dong, Buk-Gu, College of Agric. and Life science, Gwangju, South Korea.

In 1996, the outbreak of food-borne illness by Escherichia coli O157:H7 in Japan was intensely influenced to strengthen the inspection of the imported meats in Korea, and also to make every efforts to seek promptly out an infected person who suffering from diarrhea. The chemical components of corn silk, which has been used as a diuretic in Chinese medicine, were analyzed and the antibacterial activity against Escherichia coli O157:H7 was measured. Fresh corn silk was harvested and dried in a cabinet dryer at 50C. To investigate the antibacterial activity, dried corn silk was extracted with water and 50% ethanol, and the extract showed stronger activity was applied to a model food system. Corn silk was composed of 84.28% moisture, 5.77% crude protein, 0.92% crude fat, 0.78% crude ash, and 4.48% crude fiber. Seventeen amino acids were detected and glycine was the highest at 497 mg%. Free sugars were sucrose, fructose, maltose and glucose. Corn silk contained, minerals including 131 mg% of K and 55 mg% of Ca. Contents of unsaturated and saturated fatty acids were 48% and 30.9%, respectively. The strong activities of the water extract and ethanol extracts were against Escherichia coli O157:H7. In general the water extract was more effective than the ethanol extract. The lowest minimum inhibitory concentrations (MIC) of water and ethanol extracts were at 7.5 mg/disc and 12.5 mg/disc for Escherichia coli O157:H7, respectively. In a synthesized broth medium, the growth of test organisms was inhibited with the addition of 5-fold level of MIC. In sterilized milk as a model food system, the length of lag phase for the growth of test organisms was extended up to three days at 20C. This result indicated that the growth was strongly depressed. But, there was no significant difference at 4C.

Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
2:00 PM - 5:30 PM, Sunday PM

2003 IFT Annual Meeting - Chicago,