The acute oral toxicity of organogermanium, Ge-132 was evaluated in rats and mice. The changes of body weight and clinical signs were observed for 14 days after the oral administration of Ge-132, from 0.31 g/kg up to 5 g/kg for SD rats and from 1.25 g/kg up to 5 g/kg for ICR mice. No death and toxic effects were observed for 14 days. The body weight of rats was significantly decreased 1 day after the administration in the maximum dosing group, but the decrease of body weight returned to control level 3 days after dosing. No significant changes in body weight were observed in mice. Autopsy revealed no abnormal gross findings related to Ge132. Therefore, Ge-132 has no special toxic effects up to 5 g/kg, and LD_(50) values of Ge-132 are above 5 g/kg in rats and mice.
The effects of acetic acid (AA) on aerobic plate counts (APC), gram-negative bacterial counts (GNC), and generation time (GT) in chicken wings stored at 4℃ were assessed. Chicken wings were treated with 0.5-1.5% (v/v) AA at exposure times of 5 min. Treatments of AA for 5 min significantly (P$lt;0.05) reduced aerobic plate counts (APC) and gram-negative bacterial counts (GNC) on the surface of chicken wings for 8 days, respectively. After 4 days of storage, treatments of 1.0% AA and 1.5% AA for 5 min completely (P$lt;0.05) inhibited APC and GNC compared to initial controls. Based on these results, treatments of 1.0% AA and 1.5 % AA for 5 min prolonged the microbiological shelf-life for 8 days compared to those of 0.5% AA and the controls. All treatments of AA increased the lag phase and GT of aerobic microorganisms.
We have reported a sensitive, specific and simple direct competitive ELISA method to detect aflatoxin in agricultural commodities. We evaluated the ELISA for practical use to detect aflatoxins contaminated in the domestic and foreign agricultural commodities. The detection limits of the direct ELISA for residual aflatoxins in rice, pine nuts, corns, almonds, bean nuts, and pistachio were 10 ppb and in peanuts and cashew nuts were 20 ppb, which were elucidated from the standard curves of ELISA for aflatoxin fortified into the agricultural commodities. Residue studies of naturally contaminated aflatoxins in the agricultural commodities were also carried out by using direct ELISA. As the results of the studies, it was revealed that there were no residues of aflatoxins in 20 rice samples produced in south Korea, 20 pine nut samples in south Korea (9 samples), USA (1 sample) and China (10 samples), each of 20 almond, pistachio and bean nut samples in USA. However, aflatoxin residues were detected in corn samples imported from north Korea (350-585 ppb in 2 of 3 samples), from USA (109-326 ppb in 6 of a samples) and domestic corns (61-326 ppb in 7 of 17 samples). The toxins were contaminated in corn imported from USA for popcorn (17-20 ppb, in 3 of 10 samples) whereas no residues were detected in corn from south Korea and China. In case of cashew nuts imported from India, 11.4-23.1 ppb of aflatoxins were detected in 4 from 20 samples. Most of the contaminated foods were harvested before 1995. Thus, hygienic managements of the foods should be required during storage and circulation at market.
Analytical method using capillary GC/ECD was developed to determine trace residues of chlorfluazuron, 1-[3, 5-dichloro-5-trifluoromethyl-2-pyridyloxy)phenyl)-3-(2, 6-difluorobenwyl), in meat, and applied to analyze the residues in domestic and imported meats. The analytical scheme developed does not require column chromatographic cleanup; chlorfluazuron was extracted with diethyl ether and petroleum ether (50: 50), partitioned against acetonitrile, cleaned up with silica Sep-Pak cartridge, identified GC/ECD, and comfirmed by GC/MS. The mean recoveries of the pesticide in meat fortified with standard solution 0.1, 0.5, 1.0 mg/kg were ranged from 82 to 95%. The limit of detection and limit of quantitation were 0.001 and 0.005 mg/kg, respectively. Chlorfluazuron residues were not found in domestic samples, but found in imported Australian beef ranging from 0.02 to 0.17 mg/kg, detected by 18% among the samples.
A study was conducted to determine contamination status of fish sold at wholesale market in Seoul. A total of 79 samples (35 different kindry fish) were collected from the wholesale market. E. coli and coliform group bacteria were cultured and tested for sensitivity against antibiotics. The results are summarized as follows; 1. E. coli was isolated from 23 out of 79 samples (29.1%), and coliform groups from 53 out of 79 (67.1%). 2. Of coliform group, Citrobacter freundii was the most common and Enterobacter cloacae was the next. 3. 23 E. coli strains isolated from fishes were resistant to Oxacillin, Erythromycin and Lincomycin, meanwhile 23 E. coli strains were sensitive to Cefoperazone, Ceftazidime, Imipenem, and Ciprofloxacin.
The present study was carried out to know the distribution of freshwater mollusk on the Chinese liver fluke in the middle of August, 1997 at the upper area of Kyungan stream located in Yongin Kun, Kyungki province. The snails were collected from the shallow and irrigation route in a rural area located along the upper area of Kyungan stream. The snails collected by hand were brought to the laboratory and cercariae naturally shed from the snails, Parafossarulus manchouricus were examined. Parafossarulus manchouricus is medically important intermediate host of the transmission of digenetic trematoda to human. Each snail was placed in aerated tap water for the detection of cercariae and examined for expelled cercariae. Infection rate of the cercariae of Clonorchis sinensis was 3 (1.5%) among 195 individuals collected in the habitat. The identification of the cercaria of Clonorchis sinensis was performed as described by Komiya and Tajimi.
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).
초록 (Abstract) Antithiamin activities of BHA, BHT, PG and TBHQ of synthetic antioxidants on the effect of temperature and pH was determined by means of HPLC. The influence of synthetic antioxidants on the degradation of thiamin was found to be dependent on temperature and pH. The degradation of thiamin was considerably more rapid at pH 7 than pH 4. The influence on the heat of synthetic antioxidants at pH 4 and 38℃ was extremely slight, but the degradation of thiamin at pH 7 was much more rapid at 60℃ than at 38℃. After 24 hours of incubation both PG and TBHQ at pH 7 and 60℃ nearly completely destroyed thiamin. Tests of antithiamin activities showed that TBHQ, which was decomposed completely in 72 hours, was more effective than PG at pH 7 and 38℃, but BHA and BHT hardly had antithiamin activities which was evaluated under various reactions of pH and temperature. Thiamin degradation, at pH 7 and 60℃, was proportional to the concentration of PG. When the ratio of PG to thiamin was increased from 0.15:1 to 2:1, the degradation rate also increased. However, the change between ratio of 1:1 and 2:1 was negligible
Panax ginseng C.A. Meyer has been extensively used in the traditional oriental medicine as a restorative, tonic and prophylatac agent. This study was devised to develop a chemopreventive agent from panax ginseng to be able to suppress the genotoxicity and oxidative damage by reactive oxygen species, which are involved with cancer or aging. Ginseng petroleum ether extract (GPE) and one of its fraction, P2, showed an antioxidative effect on the lipid peroxidation of ethyl linoleate with Fenton's reagents and free radical scavenging effect to 1,1-diphenyl-2-picryl hydrazil (DPPH) radical generation. They also showed the suppressive effect of H₂O₂ or KO₂ induced DNA damage by single cell gel electrophoresis (SCGE). Results from our study indicate that GPE and P2 are capable of protecting lipid peroxidation, and oxidative DNA damage. Therefore, GPE and P2 may be useful chemopreventive agents which are involved with cancer and aging.
The antimutagenic effects of juices and methanol extracts from cruciferous vegetables (cabbage, red cabbage, Korean cabbage, kale, cauliflower, broccoli, radish root, leafy radish, rape leaves and shepherd's purse) on the mutagenicity induced by aflatoxin B₁ (AFB₁) and N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) were studied using Salmonella assay system. In the case of juices from the cruciferous vegetables, the juices of cabbage, kale, cauliflower and radish root in the concentrations of 50, 200 and 500 ul/plate considerably decreased the mutagenicity induced by AFB₁, and the juices of cabbage and broccoli in the concentrations of 200 and 500 ul/plate significantly reduced the mutagenicity induced by MNNG. The antimutagenic activities of the juices against AFB₁ were stronger than those against MNNG. In the case of methanol extracts from the cruciferous vegetables, the methanol extracts of kale, broccoli and shepherd's purse appeared to inhibit the mutagenicity induced by AFB₁ and MNNG in Salmonella typhim,urium test strains. The effects of the juices against mutagens quite different from ones of the methanol extracts. The juice of cabbage showed antimutagenicity, but its methanol extract was less effective. However, both juices and methanol extracts from kale and broccoli exhibited strong antimutagenic activities against the mutagens.
In order to investigate the trace metals in Korean foods, the contents of Magnesium, Zinc, Manganese, Molybdenum and Selenium are studied in this paper. As show in the Table 1; a total of 250 samples of 25 species were analyzed by neutron activation analysis. The results obtained were as follows; 1. The overall ranges and mean (mg/100 g) were; Mg, 12.212-151.346 (55.164); Zn, 0.045-38.180 (2.473); Mn, 0.003-0.796 (0.225); Mo, ND-0.035 (0.007); Se, ND-0.069 (0.016). 2. The levels of all metals except Mo in shell fishes were high and the level of Mo in spices .was higher than that in other foods. 3. The levels of Zn and Mo in oyster were higher than another spcies.
The effects of kind of vegetables and of the kind and amounts of fermented fish sauce on the formation of nitrosamine (NA) during kimchi fermentation were investigated. Kimchies made of Chinese cabbage, cucumber, and radish with fermented shrimp, anchovy and liquid sauces were fermented at 4℃ for 6 weeks and the changes in the content of nitrate, nitrite, trimethylamine (TMA), dimethylamine (DMA) and NA were studied. Nitrate content in kimchies made of Chinese cabbage, cucumber, and radish increased at the initial period of fermentation, but it decreased at the later period. Nitrite was not detected at the later period of kimchi fermentation. Overall, there have not been great changes in the contents of nitrite and nitrate. However, there have been considrable changes in the contents of TMA and DMA as fermentation progressed. Only nitrosodimethylamine (NDMA) at the level of 0.5-10.3 ug/kg was formed in three kinds of kimchies. More NDMA was formed in radish and cucumber kimchies than in Chinese cabbage kimchi. The pH was lowered faster in radish and cucumber kimchies than in Chinese cabbage kimchi. More NDMA was formed in Chinese cabbage kimchi made with fermented shrimp sauce than those with anchovy or liquid sauces. Shrimp sauce contained higher amount of DMA than anchovy and liquid sauces. The contents of NDMA tended to increase as the amount of shrimp sauce increased. The kind and amount of fermented fish sauce used for kimchi preparation may be an important factor affecting the formation of NDMA.
This study was undertaken to evaluate microbial risk degree of some processed foods in Korea. In this study the data on the outbreak of foodborne diseases during recent 18 years (1976-1989, 1993-1996. 8) were analyzed. The most frequently isolated pathogens were Salmonella (36.9%); followed Vibrio (22.0%), Staphylococcus (15.7%) and Escherichia coli (13.3%). Outbreak rate of Staphylococcus, Vibrio, E. coli and Salmonella, was 33.0%, 23.5%, 17.5% and 17.1%, respectively. Overall risk degree of pathogens by fatality rate, outbreak rate and pathogen amount for foodborne outbreak was Clostridium, 5, Staphylococcus and Vibrio, 4, Salmonella and E. coli, 3. Based on foodborne pathogens, the risk degree of raw seafoods, raw eggs and processed seafoods were 4, and those of raw meats, Doshiraks and milk products were 3. Also, based on processing characteristics of foods, the risk degree of surimi-based imitation crab was 3. Foods of the highest actual risk degree were raw seafoods and raw eggs (16); followed raw meats (15), surimi-based imitation crab (12), Doshirak (9) and milk products (6).
This study was undertaken to find out distribution and contamination sources of hazardous microbes through microbial hazard analysis on the processing steps of surimi-based imitation crab (SBIC). As a results of analysis of 9 hazardous microbes for 16 raw materials and 8 processing steps, no Samonella spp. and Escherichia coli were detected in all samples. Level and distribution of hazardous microbes in mixed color were similar to those of surimi. Changes of aerobic plate counts (APC), psychrotropic bacteria, coliforms, Staphylococcus aureus and Vibrio parnhaemolyticus showed similar trends at different processing steps. Thermotrophic bacteria and aerobic sporeformers were not detected until mixing step and feeding step, respectively and not reduced after cooking step. According to the comparison of APC at each step, it was suggested that surimi, workers and silent cutter at mixing step, and mixed color, workers and bundler at packaging step were the major contamination sources of bacteria.
This study was intended that the biochemical patterns, bioserological characteristics, resistance of antibiotics, and transferable resistance patterns of 35 Escherichia coli strains from 79 fish and shellfish samples in marine markets from August to October, 1995. The Standard plate count, coliforms and fecal coliforms were also counted in the 79 cases and analysed the correlationship each other. Geometric means of Standard plate count in seawater fish, shellfish, mollusca and crustacean were 1.4 × 105 CFU/g, 4.0 × 10^5 CFU/g, 2.4 × 10^5 CFU/g, 4.7 × 10^5 CFU/ g, and those of coliforms were 1.3 × 10¹ CFU/g, 4.8 × 10³ CFU/g, 8.9 × 10² CFU/g, 5.8 × 10³ CFU/g. There were no fecal coliforms in the fish and mollusc. However, the geometric means of coliforms in the shellfish and crustacean (1.1 × 10¹ CFU/100g, 10 CFU/100 g) were less than those of fish and mollusca. The important biochemical characteristics of E. coli distinguished from the shellfish and crustacean were motility, ornithine decarboxylase, mucate, esculin. The fermentative properties of E. coli were also sucrose, salicin, sorbitol, and raffinose. Of 35 isolates of E. coli, 13 strains (37.1%) showed the pathogenic O antisera, which were O:27 3 strains (23.1%), O:159 2 strains (15.4%) and O:148, O:119, O:142, O:158, O:136, O:18, O:128, and O:168 1 strain (7.7 %), respectively.
Foodborne diseases are serious problems throughout the world, because new pathogens have emerged. Nowadays many students eat school lunch provided by school lunch program. They are threatened by pathogens transmitted by foods. Many school children became victims of foodborne diseases. Most foodborne outbreaks were caused by mishandling foods at food service establishments. Temperature control is the most critical point of keeping the foods safe. In order to prevent foodborne diseases in schools, the managers in charge of school lunch program and officials in charge of food safety of local health department try to make sure that foods are out of danger zone of temperature. Prevention of cross contamination, and sanitization of raw foods and utensils are also emphasized by school lunch program managers and health officials.