Toxicological safety on 20 kGy-gamma irradiated Kanjang (soy sauce), Doenjang (soybean paste), Kochujang (hot pepper paste) and Chungkukjang (soy paste) was determined by SOS Chromotest. As the strain of the SOS Chromotest, Escherichia coli PQ37 was used in the condition of presence or absence of an exogenous metabolizing system (S-9 mix). Water extract or organic solvent extract was prepared from samples, concentrated and tested by SOS Chromotest with S-9 mix or not. All irradiated samples were not different from non-irradiated one in the bacterial assay maintaining the below 1.5 of IF(induction factor) values in the adapted dose of 10,000 ㎍/assay. The results indicated that any mutagenicity was not observed in 20 kGy-irradiated traditional soybean fermented foods.

Gamma irradiation at 20 kGy was applied to Kanjang (soy sauce), Doenjang (soybean paste), Kochujang (hot pepper paste) and Chungkukjang for their possible genotoxicity The genotoxicity of 20 kGy-irradiated samples was evaluated by Salmonella typhimurlum reversion assay. The Salmonella tester strains included TA98, TA100, TA1535 and TA1537 in the absence and presence of an exogenous metabolizing system (S9 mix). All samples were negative in the bacterial reversion assay with S. typhimurium TA98, TA100, TA1535 and TA1537. The results indicated that 20 kGy of gamma irradiation on water-soluble fraction of Kanjang, Doenjang, Kochujang and Chungkukjang were not shown mutagenicity.

Effect of gamma irradiation on quality properties of half-cooked noodle was studied. The noodle were treated with lactic acid(0.1%, w/w), heat(10 min in boiling water) or their combination after cooking for 3 min, and irradiated at 0, 5 and 10 kGy. The noodle were stored at 25℃ for 5 weeks and microbial population, Aw, pH, and texture profiles were examined. Fungi were completely eliminated by gamma-irradiation with 5 or 10 kGy does. Number of aerobic bacteria were also decreased by 2 and 4 log cycles with dose of 5 and 10 kGy, respectively. The D_(10) values of aerobic bacteria were 2.34-2.95 kGy. Growth of the aerobic bacteria that survived even at 10 kGy of irradiation were significantly inhibited during storage. Acidification of half-cooked noodle was suppressed by gamma irradiation but A_w were not affected. Stickiness was decreased at the beginning of storage by gamma irradiation but was restored after 3 weeks. The results indicated that the gamma irradiation would be useful to improve quality and storage stability of half-cooked noodle.

Microbial populations of total aerobic bacteria -and coliforming bacteria, TBA, Hunter's color value, heme pigments, muscle protein solubility, cooking loss and shear force were investigated for evaluating the shelf life of chicken legs gamma-irradiated at doses of 1, 3, 5 and 10 kGy with air-contained and vacuum-packaged methods. The initial microbial populations decreased with gamma irradiation depending upon the dose, and microorganisms in the vacuum-packaged samples were inhibited more than those in the air-contained samples. TBA values were higher in the air-contained samples than in the vacuum-packaged samples. Hunter's L and a values of the surface and inside of the legs increased by gamma irradiation, showing a bright red color and the red color was maintained during the storage of both samples. The concentrations of oxymyoglobin among the heme pigments increased by gamma irradiation. Muscle protein solubility slightly increased by increasing the applied dose. There were no significant differences in the cooking loss and shear force values. In conclusion, the combination of gamma irradiation and vacuum-packaging could extend the shelf life of chilled chicken without deterioration of the quality.

The effect of gamma irradiation on the survival of spore bacteria was investigated in frozen cells (-18℃) with 0.1 M phosphate buffer and inoculated cells in beef. In the case of the frozen cells at log phase, the radiation D_(10) and 12D_(10) values were 0.29 kGy and 3.48 kGy in Bacillus subtilis, 0.39 kGy and 4.68 kGy in Bacillus cereus and 0.46 kGy and 5.52 kGy in Clostridium perfrigens. And inactivation factors were 6.52-10.34 and 10.87-17.24 at the dosage of 3 kGy and 5 kGy, respectively. The radiosensitivity of inoculated cells in beef showed the D_(10) value of 0.59-0.76 kGy, the 12D_(10) value of 7.08-9.12 kGy, and inactivation factors of 3.95-8.47. The radiosensitivity of the frozen cells was higher than that of inoculated cells in beef.

A study was undertaken to determine the thermal inactivation of Escherzchia coli O157:H7 as influenced by the effects of temperature, time, suspension medium and ascorbate. Tryptic soy broth was more heat resistant than phosphate buffer (pH 7.1), with D values of 1.52-1.68 min at 60℃ and 1.51-1.63 min at 70℃ compared with 1.52-1.65 min at 60℃ and 1.26-1.61 min at 70℃ for phosphate buffer as suspension medium. E. coli O157:H7 was completely inhibited within 30 min when small inoculum (10^6 CFU/ml) was heated at 70. When E. coli O157:H7 was preheated at 48℃ for 60 min in phosphate buffer before heating, D values were 1.28-1.60 min at 60℃, and 1.13-1.56 min at 70℃, showing that preheating increases the heat resistance of the strain. Phosphate buffer containing ascorbate (0.001 M) was enhanced the thermal inactivation of the strain when inoculated as large inoculum (10^9 CFU/ml), while ascorbic acid was no effect at low cell concentrations (10^6 CFU/ml).

Effects of benzoate (0-0.6 g/l and sorbate (0-2.0 g/l) on the growth of Escherichia coli O157:H7 in tryptic soy broth at various pH levels (4-8) and temperatures (4℃, 37℃) were investigated. Benzoate and sorbate were inhibited the growth of E. coli 0157:H7 up to 12 hours cultivation at 4℃, and 2.0 g/l sorbate was only inhibited during 48 hours cultivation at 37℃. Among the pH levels tested, pH 4 showed significant inhibitory effect against the E. coli O157:H7 on 4℃ and at 37℃, respectively. When used in combination 0.2 g/l benzoate and sorbate were completely inhibited the growth of E. coli O157:H7 on pH 4 and at 37℃. While on pH 5 at 4℃, all of the concentration tested did not exert any inhibitory effect. The combined effects were retarded more than single treatment of E. coli O157:H7.

For the purpose of improving hygienic quality of dried-Angelica Keiskei Koidz powder, the effects of ozone treatment and gamma irradiation on the microbial decontamination and physicochemical properties were investigated. Gamma irradiation at 5 to 7.5 kGy resulted in sterilizing total aerobic bacteria, molds and coliforms below detective levels, while ozone treatment for 8 hours up to 18 ppm did not sufficiently eliminate the total aerobic bacteria of the sample. The physicochemical properties of the sample were not changed by gamma irradiation up to 7.5 kGy, whereas, ozone treatment caused remarkable changes in pH, TBA value, chlorophyll, carotenoid and fatty acid compositions. Therefore, this investigation demonstrated conclusively that gamma irradiation was more effective than ozone treatment for decontaminating and sterilizing the dried-Angelica Keiskei Koidz powder, with minimal effect on the physicochemical properties analyzed.

For the purpose of improving hygienic quality of health-foods, sterilization effects of y ray and ozone on microoganisms associated with food cultured in the media and contaminated in Angelica keiskei powder were investigated. Ozone was immersed in water and sprayed in air, on the concentration of 3 mg liter^(-1) at an air flow rate of 5 liter min'. Test strains cultured in the media completely inhibited by γ-ray at irradiation doses of 0.25--2 kGy. In the case of ozone, test bacteria inactivated after treatment of 10-20 minutes, but test mold, Aspergillus llavus was not effective. Strains contaminated in Angelica keiskei powder completely inhibited by γ-ray at irradiation doses of 2.5-7.5 kGy. However, when the powder was sprayed with ozonized air for 10 hours, Bacillus subtilis and Staphylococcus aureus among five strains were eliminated.

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.

The yields of solvent fractions of irradiated red ginseng powder were increased in the order of petroleum ether(PE)$lt;diethyl ether(DE)$lt;ethyl acetate(EA)$lt;n-butanol (BU)$lt;aqueous fraction(AQ), and did not show any changes in fraction yields by irradiation dose levels. Inhibition activities of lipid peroxide formation were increased in the order of AQ$lt;BU $lt;PE$lt;EA$lt;DE. Inhibition activities of malonaldehyde formation were increased in the order of AQ≤BU$lt;EA$lt;PE$lt;DE. AQ fraction showed little effects on the antioxidative activity and all the activities of the samples did not changed by gamma irradiation. The reverse mutation assay using Salmonella typhunurium (TA98, TA100 and TA102) demonstrated that the nonirradiated and irradiated red ginseng powder extract did not have mutagenic activity (presence of S9 mix or not). The chromosomal aberration test in mammalian animal cell (Chinese hamster lung fibroblast, CHL) showed no significant increase in incidence of structural and numerical aberrations, comparing gamma-irradiated red ginseng powder extracts to nonirradiated red ginseng powder extract in the concentration of the sample producing cytotoxicity(presence of S9 mix or not). Therefore, gamma-irradiatied red ginseng powder (upto 10 kGy) could be safe on the genotoxic point of view.

For improved preservation of boiled-dried anchovies, the current preservation method of corrugated-cardboard box packaging and freezing below - 18℃ was compared to the nylon/polyethylene(NY/PE) packaging along with cooling temperature ranging from 5℃ to 10℃ as well as ambient condition for eight months by determining physicochemical quality of stored samples. Lipid oxidation of stored anchovies and their browning increased with storage time. The phenomenon was delayed under the conditions of lower temperature and air-tight packaging. As quality-indicative criteria of stored anchovies, carbonyl value(r=-0.989), browning (r=-0.949) and color a value(r=-0.989), browning(r=-0.965), Hunter's color b value (r=-0.949) and color a value(r=-0.940) showed a highly-negative correlations with organoleptic qualities of the samples. Based on the above results, air-tight packaging in a laminated film and subsequent storage at cooling temperature was found to be a possible alternative to the current freezing-storage of boiled-dried anchovies from the physicochemical point of view.

For improved preservation of boiled-dried anchovies, the current preservation method of corrugated-cardboard box packaging and freezing below - 18℃ was compared to the nylon/polyethylene(NY/PE) packaging along with cooling temperature ranging from 5℃ to 10℃ as well as ambient condition for eight months by determining physicochemical quality of stored samples. Lipid oxidation of stored anchovies and their browning increased with storage time. The phenomenon was delayed under the conditions of lower temperature and air-tight packaging. As quality-indicative criteria of stored anchovies, carbonyl value(r=-0.989), browning (r=-0.949) and color a value(r=-0.989), browning(r=-0.965), Hunter's color b value (r=-0.949) and color a value(r=-0.940) showed a highly-negative correlations with organoleptic qualities of the samples. Based on the above results, air-tight packaging in a laminated film and subsequent storage at cooling temperature was found to be a possible alternative to the current freezing-storage of boiled-dried anchovies from the physicochemical point of view.