Listeria monocytogenes and L. ivanovii are important food-pathogens for human and animal. The diagnostic of Listeria in food using culture medium requires time and laborwork, because there are many other nonpathogenic species like L. innocua, L. welshimeri, L. seeligeri and L. grayi in Genus Listeria. For these reasons, Lismix multiplex PCR method was developed as a rapid method for the detection and identification of Listeria. In this study we developed a practical system of Lis-mix PCR detection for the application to food samples and new developed Siw-mix III PCR system. Using this Lis-mix PCR system overall 69 listerial strains were successful species-identified and confirmed. Also, the Siw-mix III PCR system allows the species-specific identification among L. ivanovii, L. welshimeri and L seeligeri in a single PCR.
Campylobacter spp. isolated and identified from the raw chicken carcasses in food service, were characterized. Total bacterial counts on the skins of raw chicken were 10 ⁴-10^6 CFU/g and a total of 205 strains were primarily isolated after enrichment culture and selective culture of the sample with candle and microaerophilic chamber method. Among them, twenty eight strains of Gram-negative, catalase-positive and oxidase-positive were further isolated by the determination of biochemical characteristics. Only sixteen strains of them were finally identified as Campylobacter with PCR of pA and pB primers. Nine strains, more than half of them, have grown at 42℃ and 25℃ and seven strains defined as thermophilic Campylobacter grew not at 25℃, but at 42℃. Therefore, more careful management of food safety for raw chicken is needed in food service. Particularly, we should concern the raw chicken carcasses with high bacteria contamination, more them 10^5CFU/g, which possibly includes Campylobacter spp. grown at low temperature.
본 연구에서는 5종의 유산균들 (Lactobacillus reuteri, L. acidophillus, L. bulgaricus, L. casei and Bifidobacterium longum)의 식중독 균들에 대한 항균력을 조사하였다. 각 유산균들을 3가지 서로 다른 조건 (MRS+glucose, MRS+0.5 M glycerol, 0.25 M glycerol solution)에서 배양한 후 그 상층액이 포함된 Moulter Hinton Agar에 8종의 유해균들을 접종하였다. MRS+glucose, MRS+0.5 M glycero에서의 상층액을 이용한 실험에서는 L. reuteri의 항균력이 다른 유산균들에 비해 높지 않았으나 0.25 M glycerol solution에서는 탁월하게 높은 결과를 나타내었다. (p<0.05). 0.25 M glycerol solution에서 나타난 높은 항균력은 L. reuteri가 glycerol을 이용하여 생산하는 reuterin이란 물질 때문이라 생각되며, 0.25 M glycerol solution의 상층액을 500 MHz Nuclear Magnetic Resonance (NMR)를 통해 분석한 결과 reuterin의 존재를 확인할 수 있었다. 3가지 조건 하에서의 항균력 시험 결과 가장 높은 항균력을 나타낸 3가지 유산균들 (Lactobacillus resuteri, L. bulgaricus, L. casei)을 선발, 각각 최고의 항균력을 나타낸 조건으로 배양하여 최소사멸농도 (minimum bactericidal concentration)를 측정한 결과, L. reuteri가 생산한 reuterin이 광범위 항균물질임을 확인하였다. 또한 pH 적정, pepsin 혹은 trypsin 처리를 한 후 3가지 유산균들의 항균력 변화를 조사한 결과 L. bulgaricus와 L. casei의 항균력은 이러한 조건에서 상당히 감소한 반면 reuterin의 항균력은 아무런 영향을 받지않았다 (p<0.05). 이상의 결과들로 보아 주요 유산균들 중에서 L. reuteri의 항균력이 가장 우수하면서 광범위하였으며 이는 L. reuteri가 분비하는 항균물질인 reuterin에 기인한 것으로 사료된다. 또한 reuterin의 항균력은 타 유산균과는 달리 장관내 pH나 단백질 분해효소에 의해 영향을 받지 않으므로 인체나 동물 장관에서 가장 높은 효력을 가진다고 판단할 수 있다.
Generally, non-aflatoxigenic fungi, such as Aspergillus oryzae, and Aspergillus niger are main microflora in Korean traditional fermented foods including Meju and soybean paste, but sometimes, Aspergillus flavus and Aspergillus parasiticus can be contaminated and accumulated aflatoxins during fermentation and storage. So the screening of aflatoxigenic strains in fermented traditional food is very important to improve the sanitary quality of those foods. In this work, we screened aflatoxin producing fungi from commercial Meju and soybean paste in Western Gyeongnam by immunoassay. Samples were randomly purchased from market of the commercial Meju(10 EA) and soybean paste(20 EA) in nine areas of Western Gyeongnam. Of the samples collected, 24 strains and 22 strains of Aspergillus sp. were isolated from Meju and soybean paste, respectively. The isolated strains were cultured on SLS media at 25℃ for 15 days. The cultured broth were extracted with ethyl acetate and were analysed to determine aflatoxin B₁(AFB₁) by direct competitive ELISA(DC-ELISA). Six strains(25%) isolated from Meju, and 2 strains(9%) isolated from saybean paste, were confirmed as aflatoxin producing strains. The average range of aflatoxin productivity of isolates from Meju was 54.6 ± 38.7 ng/ml and that from soybean paste was 11.1 ± 8.6 ng/ml, respectively. Among them, isolated strain No. M-5-4 produced a high level of AFB₁ and showed 98.26 ng/ml of AFB₁. Every isolates were also re-confirmed their AFB₁ productivity by thin layer chromatography(TLC). The TLC results also showed same trend as DC-ELISA results. As the above results, the screening of hazard mycotoxigenic fungi from traditional fermented foods should be necessary for the safety and the application of HACCP system in the food manufactory in Korea.
Despite to the reality that the outbreaks from food poisoning in Korea have been continuously increasing in the last two decades, it was very much neglected even in the public health field in Korea. Food poisoning outbreaks resulted in many cases not only in the damage of health but also in the death of many lives. However, this problem can be effectively solved by efforts through health education activities, but not solely by the legal measures. This study was carried out to provide information that can be used in planning health education programs and proposing new rules to prevent any possible outbreaks from food poisoning. The main problems contributing to food poisoning outbreaks in an institutional setting or school catering and at home were reviewed and analyzed through the epidemiological investigations and articles related to food poisoning in the last a decade (1991-2000). Accordingly, the data presented in this study are sufficient to show and prove the significant trends in food poisoning accidents in Korea. The major findings investigated in this study are as follows. The frequency of food poisoning accidents as well as the number of victims have continuously increased in Korea. The number of victims per food poisoning accident is also increased from 20 persons in 1990 to 69.8 persons in 2000. Therefore, we should realize that the group poisoning outbreaks occur more frequently and the size of group poisoning accidents is getting larger. Among four seasons, the food poisoning accidents occurred more frequently in the summer (May-September) until 1997. However, after 1997, the food poisoning accidents occurred evenly in three seasons except the winter. The most important bacteria that cause food poisoning in Korea were Salmonella spp., Vibrio spp. and Staphylococcus aureus. They occupied 85-90% of the rates of accidents and the number of victims. And, the major category of food causing outbreaks in Korea are meats, raw and undercooked sea foods and compound food as Kimbab and lunch box. Among meats, the most food poisoning accidents were caused by pork. The frequency of food poisoning accidents at individual households tends to decrease continuously. Whereas, the rates of accidents at the public restaurants and food service establishments are comparatively increasing. Therefore, we must improve the quality of the sanitation management in food service establishments through HACCP and post- administration of HACCP.
This study was performed to survey and evaluate the contents of caffeine in commercial palatability foods by HPLC. The contents of caffeine in commercial palatability foods were 9.0-49.2 mg in black tea, 35.9-141.4 mg in coffee, 12.4-48.0 mg in green tea, 7.1-16.5 mg in brown rice green tea, 22.8 mg in cocoa tea, 10.3-25.0 mg in cola and 10.0-48.2 mg in ice bar(coffee) respectively. The contents of caffeine extracted from black tea, coffee(roasted beans) and green tea were rapidly increased for five minutes from the extraction initiation, and were not nearly changed after ten minutes. Moreover, the caffeine contents were increased until 100℃ of extraction temperature.
This study was conducted to determine the content of inorganic metals in botanical pills and assess the safety of mineral balance in body. Inorganic metals (Fe, Ca, Zn, Na, Mg, K, Pb, Cd, Cr) were detected in 11 kinds, 51 samples by Atomic Absorption Spectrophotometer. The average concentration of inorganic metals in botanical pills was in the order of K(7933.32 mg/kg)$gt;Na(5848.58 mg/kg)$gt;Ca(2441.60 mg/kg)$gt;Mg(1595.34 mg/kg)$gt;Fe(353.14 mg/kg)$gt;Zn(22.49 mg/kg)$gt;Cr(3.51 mg/kg)$gt;Pb(0.24 mg/kg)$gt;Cd(0.09 mg/kg). In samples, Moms and Laminaria contained a great quantity of K and Na, Acanthopanacis cortex, Eucommia ulmoides, Pinus densiflora, Lycii fiuctus, Allium sativum for. pekinense, and Platycode radix had much more amount of K than that of Na, in the mean time, Artemisia capillaris, Carthamus tinctorius seed, and Rubi fiuctus had various kites of plenty inorganic metals. The contents of Pb in grouped samples by used parts, were in the order of radiac(0.54 mg/kg)$gt;cortex(0.36 mg/kg)$gt;leaves (0.20 mg/kg)$gt;fructus(0.20 mg/kg)$gt;seed(0.07 mg/kg), those of Cd were radix(0.16 mg/kg)$gt;leaves(0.09 mg/kg)$gt;fiuctus (0.07 mg/ kg)$gt;seed(0.06 mg/kg)$gt;cortex(0.03 mg/kg), those of Cr were radix(6.34 mg/kg)$gt;cortex(4.25 mg/kg)$gt;fructus (4.20 mg/ kg)$gt;leaves(2.14 mg/kg)$gt;seed(1.67 mg/kg). In the assessment of risk by the daily intake of botanical pills, the amount of Zn, whose PTWI was 7,000 ㎍/kg b.w/week, covered 0.13-0.83%, that of Pb, whose PTWI was 25 ㎍/kg b.w/week, coverd 0.24-1.94%, and that of Cd, whose PTWI was 7 ㎍/kg b.w/week, covered 0.32-2.08% of it.
This study was conducted to determine the content of heavy metals in canned foods and soft drinks available on the Korean markets. Trace metals (Pb, Cr, Cd, and Sn) were detected in 24 kinds, 120 samples by Atomic Absorption Spectrophotometer. The average concentration of heavy metals in canned foods was in the order of Sn (6.930 ppm)$gt;Cr (0.050 ppm)$gt;Pb (0.030 ppm)$gt;Cd (0.008 ppm), which was the same order in soft drinks as Sn (3.519 ppm)$gt;Cr (0.080 ppm)$gt;Pb (0.024 ppm)$gt;Cd (0.001 ppm). The total contents of heavy metals in canned fruits and fiuit juices were relatively higher than those in cans and drinks made of vegetable and fish. It can be supposed that the high acidity owing to the organic acid of fruit itself promotes to extract metals from can materials, and although fish usually contains more heavy metals than vegetables, canned fish revealed low level because internal organs and most of skin which had more heavy metals than meat were removed throughout canning process. Because processed foods such as canned foods and soft drinks are very popular with the children and adolescence according to the change of life style and eating habit, and the possibility of exposure to heavy metals by the habitual intake of these is increasing simultaneously, it is suggested that more practical study about the process of exposure and the amount in each step is needed for the assessment of safety.
This study was concentrated that the contents of heavy metals were estimated from 782 samples of sold fisheries in Seoul(33 species in fishes, 15 in bivalves, 12 in crustaceans and 10 in others) by Atomic Absorption Spectrometer. The contents of As, Cd and Pb [minimum-maximum (mean)] were N.D.-0.162 mg/kg(0.021), 0.001-0.120 mg/kg(0.014) and 0.015-0.499 mg/kg(0.111) in fishes, 0.003-0.311 mg/kg(0.052), N.D.-1.905 mg/kg(0.182) and 0.013-0.462 mg/kg(0.138) in bivalves, N.D.-0.328 mg/kg(0.042), 0.002-1.113 mg/kg(0.079) and 0.006-0.510 mg/kg(0.109) in crustaceans, N.D.-0.181 mg/kg(0.024), 0.001-0.214 mg/kg(0.033) and 0.010-V0.877 mg/kg(0.118) in others respectively, bivalves were the highest than others. The average weekly intakes of three metals from sold fisheries took about 1.4-26.4% of PTWI (provisional tolerable weekly intakes) that FAO/WHO Joint Food Additive and Contaminants Committee had set to evaluate their safety.
Foods constitute a large portion of heavy metal exposure toward general population and attract a deep concern with respect to assuring human health. This study summarized published data in Korea on the content and dietary intake of heavy metals and assessed their risk potential in comparison with foreign data. An analysis for the yearly fluctuation of metal contents including arsenic, cadmium, mercury and lead by food group (marine fishes, coastal shellfishes, freshwater fishes, cereal grains) exhibited a decreasing trend from the 1970s to the 1990s. When compared with domestic standards of heavy metals, their mean contents were below the limit and their maximum values seldom exceeded the limit. The data on the dietary intake of heavy metals by Koreans showed a decreasing trend from the 1980s to the 1990s. The average intakes of As and Hg were 6-8% and those of Cd and Pb were 50-80% of PTWI(provisional tolerable weekly intake), all of which were below the tolerance. As the extreme intakes of these metals may exceed the PTWI, a careful assessment for them may be necessary. Dietary intakes of Cd, Hg and Pb by Koreans lie in the mid-level among countries cited in the GEMS/Food monitoring data. As fishery foods are suspecious of contamination with Hg, Cd and As, and foods in general are with Pb, it is necessary to establish legal limits for these metals and monitor any progress of their contamination. Furthermore, overall assessment of exposure to heavy metals from all sources including foods, air, drinking water and occupation should be made in order to confirm the dietary risk factors and to assure the safety of food resources.
The actual overall migration data obtained from plastic food packaging materials into food simulants under high temperature testing conditions as described in the regulations of European Union, USA, and Korea or Japan were compared. Overall migration values(OMVs) with non-fatty food simulants under high temperature conditions were observed to be generally below 2.5 mg/dm^2 except polyamides(CPA and PA 6,6) which were tested at 121 for 2 hrs. As for the fatty food simulants, the OMVs with soybean oil were higher than other simulants. Among the films tested, PVC wrap showed higher OMVs ranging betwn 23.9 and 54.6 mg/dm^2 than others. The OMVs were measured at higher level with the elevation of contact temperature and the extension of contact time, and in fatty food simulants rather than in non-fatty simulants. Under similar testing temperature and time conditions. the OMVs tended to be increased in polar films like PA with polar simulants, and contrarily in non-polar films like PO with non-polar simulants. It is noteworthy that a discrepancy with regard to the result of OMVs was observed for some films as a result of different migration testing methods and conditions of each country areas.
Growing evidence indicates that oxidized low density Iipoprotein (LDL) may promote atherogenesis. Therefore, inhibition of LDL oxidation may impede this process. The effect of chitin sulfate on the susceptibility of human low density lipoprotein (LDL) to macrophages-induced oxidation was investigated by monitoring a thiobarbituric acid reactive substance (TBARS). Chitin sulfate inhibited LDL oxidation by macro phages in a dose dependent manner, with a 50-100μM, as assessed by TBARS assay. Chitin sulfate, at 100 μM, almost completely inhibited the macrophage-induced increase in electrophoretic mobility of LDL. Also, chitin sulfate almost completely inhibit O₂^- at concentration of 100 μM. These observations suggest that chitin sulfate might be an effective in prevention of atherosclerosis.
Oxidative stress is believed to play an important role in the development of vascular complications associated with diabetes mellitus. We examined the antioxidative effect of sesamin and sesamolin on the preventing the development of insulin dependent diabetes mellitus using streptozotocin-induced Sprague Dawley diabetic rats. From 48 hours after injection of streptozotocin (60 mg/kg body weight), a portion of diabetic rats were fed with 0.2% sesamin and sesamolin containing diet for 3 weeks. There were significant differences of blood glucose and kidney weight between diabetic ports and control. Sesamin and sesamolin increased glutathione-S-transferase activity in kidney. The concentration of the thiobarbituric acid-reactive substances in the serum, liver, and kidney of diabetic rats administered sesamin and sesamolin decreased significantly as compared with that of the non-treated diabetic group. Dietary sesamin and sesamolin suppressed the oxidative stress in the diabetic rats. These results demonstrated that sesamin and sesamolin are potential and effective antioxidants that can protect the complications associated with diabetes.