Irradiated and non-irradiated Korean medicinal herbs were extracted by water and 70% ethanol. Antimicrobial activity of these extracts were investigated against selected food hygiene microoganisms. The ethanol extracts of the non-irradiated Agrimonia pilosa ledebour japonica Nakai, Curcuma longa Linne and Angelica gigas Nakai were completely inhibited on four species of bacteria, such as Vibrio parahaemolyticus, Clostridium perfringenes, Bacillus subtilis and Staphylococcus aureus. Also, above four strains did not have antibacterial activity in the water-ethanol mixtures. Futhermore, the ethanol extracts of the non-irradiated Agrimonia pilosa ledebour Japonica Nakai, Curcuma ledoaria Roscoe, Curcuma longa Linne and Scutellaria baikalensis George were shown inhibitory effects against Aspergillus flavus and Penicillium islandicum. And the water extract of Scutellaria baikalensis George was the same effect to these molds. Essentially the same results were observed when samples irradiated at a dose of 10 kGy.

D_(10) values obtained for radiation alone in Bacillus subtilis and Clostridium perfrigenes were 0.35-0.48 kGy in vegetative cells, and 2-2.08 kGy in spores, respectively. Irradiation dose of 24 kGy completely inhibited spores. In the case of heat treatment, D_(50, 60) values ranged from 10 to 14 minutes in vegetative cells, and D_(70, 80, 90), values ranged from 10 to 140 minutes in spores. In the case of combined treatment with heat and radiation, D_(10) values ranged from 1 to 1.25 kGy in vegetative cells, and from 3.42 to 3.61 kGy in spores. Thus, resistance of cells to gamma radiation did not seem to be influenced by pre-heating.