• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.247-258
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• 1994

A total of 31 commercial dried marine food products, consisting of 14 fishes, 2 shellfishes and 2 seaweeds species were analyzed for their contents of precusors of N-nitrosamine such as dimethylamine(DMA), trimethylamine(TMA), trimethylamine oxide (TMAO), betaine and nitrate and nitrite nitrogen as factors of N-nitrosamine formation. Carcinogenic N-nitrosamines were extracted by a steam distillation apparatus and were analyzed for their components using a gas chromatography-thermal energy analyzer. N-nitrosodimethylamine(NDMA) was confirmed by a gas chromatography-mass spectrometry. The contents of betaine nitrogen in samples were in the range of $5.2{\sim}373.8mg\%$ and were significantly higher than tertiary amines such as TMA and TMAO. DMA nitrogen in those samples was in the range of trace-31.2ppm and was high, in the dried shark(31.2ppm), alaska pollack($22.9{\sim}24.3ppm$) and octopus($17.9{\sim}18.4ppm$). In dried laver and sea mustard, however, amines were not detected at all. The levels of nitrate nitrogen in the dried marine samples ranged from zero to 16.8ppm and were high in the dried stingray(16.8ppm), alaska pollack(16.3ppm) and squid($2.2{\sim}12.4ppm$), but were less than 1.0 ppm in other samples. The levels of nitrite nitrogen were lower than those of nitrate nitrogen and it was not detected in dried sea cucumber, laver and sea mustard. Twenty eight of 31 samples contained NDMA($range=1.2{\sim}86.0ppb$), which was the only volatile N-nitroso compound found. The NDMA levels of dried stingray($2.8{\sim}86.0ppb$), alaska pollack($8.2{\sim}55.5ppb$), squid($3.3{\sim}53.2ppb$), yellow corvenia($45.9ppb$) and plain dried shrimp($15.4{\sim}17.9ppb$) were high. However, it was not detected in dried sea cucumber, laver and sea mustard. Samples, containing high levels of NDMA, also contained high nitrate and nitrite nitrogen. From above results, it can be concluded that nitrate and nitrite were major factors for the formation of NDMA in dried marine food products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.289-295
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• 1993

The present paper was investigated in the inhibitory action of vegetable and seaweed water-soluble extracts on the formation of carcinogenic N-nitrosodimethylamine(NDMA). The vegetable and seaweed extracts obtained from garlic(Allium sativum), onion(Allium cepa), green onion(Allium fistuiosum), chinese pepper(Fagara mandshurica), green pepper(Capsicum annuum), red pepper(Capsicum annuum), ginger(Zingiber officinale), carrot(Daucus carota), laver(Porphyra tenera), sea lettuce(Entero compresa), sea mustard(Undaria pinnatifida) and sea staghorn(Codium fragile) were incubated with sodium nitrite-dimethylamine mixtures at $37^{\circ}C$ under different pH conditions The formation of NDMA was reduced to $10{\sim}40\%\;and\;25{\sim}50\%$ by the addition of vegetable and seaweed extracts 30mg at pH 1.2, respectively. The inhibition degree by the extracts at pH 1.2 was similiar to that at pH 4.2 and to that by ascorbic acid at pH 1.2. The inhibitory action of the extracts against NDMA formation was not decreased by heat treatment at $80^{\circ}C$ for 10min, but decreased by the treatment of sodium borohydride. It is assumed that reducing powers of the extracts participated in their inhibitory actions.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.361-368
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• 2018

N-nitrosamines are probable or possible human carcinogens, which are produced by the reaction between secondary amines and nitrogen oxide in the acidic environment or by heating. Common risk assessment procedure involves the comparison between exposures expressed in the unit, mg/kg body weight/day and the Health-Based Reference dose expressed in the same unit. This procedure is suitable for the policy decision-making and is considered as inappropriate for the consumers to get information about their dietary decision-making. Therefore, the distributions of NDMA (N-nitrosodimethylamine), NDBA (N-nitrosodibutylamine), the six N-nitrosamines (NDMA, NDBA, NDEA (N-nitrosodiethylamine), NPYR (N-nitrosopyrrolidine), NPIP (N-nitrosopiperidine), and NMOR (N-nitrosomorpholine) in the menus grouped based on the presence of main ingredients and cooking methods were analyzed to generate consumer-friendly information regarding food contaminants. Recipes and intakes were taken from 2014 to 2016 KNHANES (The Korean National Health and Nutrition Examination Survey) and only the data from ages of 7 years or older were used. The contamination data were collected from the 2014~2016 Total Diet Study and all the analysis were performed using R software. Rockfish, eel, anchovy broth and pollock were mainly exposed to N-nitrosamines. In terms of cooking methods, soups and stews appeared to contain the highest amount of N-nitrosamines. Cereals, fruits, and dairy products in the ingredient categories, and rice dishes and rice combined with others in recipe categories had the lowest level exposure to N-nitrosamines. In case of N-nitrosamines, unlike other cooking related food contaminants, boiled dishes such as soups and stews and dishes mainly consisting of fishes and shellfishes had highest level of exposure, showing a large discrepancy with the previous thought of processed meat is the main source of N-nitrosamines.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1560-1565
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• 2004

There are about 50 kinds of salted and fermented fish in Korea, and they have been used as a necessity for the preparation of kimchi. There is next to nothing for the studies of finding out the cause of N-nitrosamine formation by using the salted and fermented anchovies. In order to predict the possibility of N-nitrosamine formation and mutagenicity from gastric digestion of Korean Jeotkal, correlation of N-nitrosodimethylamine (NDMA) and mutagenicity of the salted and fermented anchovy under simulated gastric digestion was investigated through mixture system of nitrate, thiocyanate, formaldehyde and ascorbic acid to the anchovy product aged at room temperature (18~20$^{\circ}C$) for 60 days. NDMA formation of fermented anchovy under simulated gastric digestion was accelerated by the increase of nitrate, thiocyanate and formaldehyde concentration and was inhibited by the addition of ascorbic acid as an inhibitor, showing that its inhibition rate was 71.3% at 4 mM as compared with control group. Mutagenicity in anchovy digest added with several level of nitrite, thiocyanate and formaldehyde was increased, while it was markedly decreased in addition of ascorbic acid.

• Parasites, Hosts and Diseases
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• v.51 no.6
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• pp.711-717
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• 2013

Opisthorchis viverrini (O. viverrini) is a well-known causative agent of cholangiocarcinoma (CCA) in humans. CCA is very resistant to chemotherapy and is frequently fatal. To understand the pathogenesis of CCA in humans, a rodent model was developed. However, the development of CCA in rodents is time-consuming and the xenograft-transplantation model of human CCA in immunodeficient mice is costly. Therefore, the establishment of an in vivo screening model for O. viverrini-associated CCA treatment was of interest. We developed a hamster CCA cell line, Ham-1, derived from the CCA tissue of O. viverrini-infected and N-nitrosodimethylamine-treated Syrian golden hamsters. Ham-1 has been maintained in Dulbecco's Modified Essential Medium supplemented with 10% fetal bovine serum for more than 30 subcultures. These cells are mostly diploid (2n=44) with some being polyploid. Tumorigenic properties of Ham-1 were demonstrated by allograft transplantation in hamsters. The transplanted tissues were highly proliferative and exhibited a glandular-like structure retaining a bile duct marker, cytokeratin 19. The usefulness of this for in vivo model was demonstrated by berberine treatment, a traditional medicine that is active against various cancers. Growth inhibitory effects of berberine, mainly by an induction of G1 cell cycle arrest, were observed in vitro and in vivo. In summary, we developed the allo-transplantable hamster CCA cell line, which can be used for chemotherapeutic drug testing in vitro and in vivo.

• The Korean Journal of Mycology
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• v.16 no.4
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• pp.193-203
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• 1988

The changes of pH, titrable acidity, nitrite and dimethylamine(DAM) content in the various different kinds of the rice wine staters during the fermentation were studied, and the changes of nitrosodimethymaine(NDMA) contents were also determined by High Pressure Liquid Chromatography. After 24hrs, fermentation rice wine starter, pH was generally decreased to below 5 and after full fermentation the acidities were from 0.51 to 0.89 as succinic acid. After 12hrs, fermentation nitrate contents were rapidly decreased. The large amount of nitrite was formed in the beginning of the fermentation. But by the increase in the acidity due to the further fermentation nitrite contents were gradually disappeared. Generally the DMA contents of each rice wine starter were kept unchanged. On completion of fermentation, NDMA contents of starter added with nitrite and DMA were 472.1 ppb. The starter added with DMA was 329.0 ppb, whereas the other added with nitrite was 229.0 ppb, and control without addition of nitrite and DMA was 24.4 ppb. But the rice wine sold in market was not detected any NDMA at all.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.406-411
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• 1998

Representive cured products such as ham and sausage produced in Korea were purchased at retail and cooked using heating tools such as a gas range (GR), an electric range (ER) and electric range after boiled (BE). Changes of N-nitrosamine (NA), nitrate and nitrite in the cured meats containing< $2.0\;\mu\textrm{g}/kg$ of N-nitrosodimethylamine (NDMA) were checked and analyzed during their cooking process. Contents of nitrate and nitrite in ham products prior to cooking were 2.0 and 1.8 mg/kg, respectively; their contents in regular hams were slightly increased, but those of nitrate in press hams were decreased while those of nitrite were increased during its cooking process. Their contents in sausage products were 1.8 and 0.9 mg/kg; those of nitrate were decreased, while nitrite were slightly increased during its cooking process. NDMA detected only NA in all the collected cured products. Changes of NDMA, regardless of cooking methods, tend to drastically increase in all samples after their cooking; Its contents were increased by average 6.0~70.7 times in the GR samples, by average 2.4~39.2 times in the ER samples and by average 7.0~56.3 times in the BE samples. Virtually, the fact that all of this nitrosamine appeared to arise by the action of precursor such as NOx was produced during the cooking of cured products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.1
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• pp.45-53
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• 1997

Salted mackerel(Scomber japonicus) is favorite diet in Korea from ancient times. The formation of N-nitrosamine and amines such as VBN, TMAO, TMA and DMA in salted mackerels were investigated when nitrite was added to salting water at the concentration of 0, 100, 500 and 1000mg/kg and influence of cooking method on the formation of N-nitrosamine was also analyzed. The content of VBN in mackerel during the salting increased contineously; after 50 days it was approximately more than 23.8 times as compared with that of raw sample. The TMAO nitrogen decreased while TMA increased in mackerel during the salting, the amounts of TMAO and TMA were 3.7~21.0mg/100g and 15.0~20.4mg/100g in salted mackerel, respectively. The content of DMA nitrogen increased remarkably in mackerel during the salting; DMA in sample salted for 50 days reached about 16.0 times more than that of raw sample. N-Nitrosodimethylamine (NDMA) content of control sample was detected less than 1.0$\mu\textrm{g}$/kg, but nitrite addition to salting water at 100, 500 and 1000ppm resulted in NDMA content of 8.1~14.6$\mu\textrm{g}$/kg, 24.5~45.5$\mu\textrm{g}$/kg and 53.8~77.2$\mu\textrm{g}$/kg, respectively. In contrast, cooked counterparts contained 3.3~12.6$\mu\textrm{g}$/kg of NDMA. In general, more NDMA were produced during cooking when samples cooked using direct heating methods such as a gas range and a briquet fire than when samples were cooked using indrect heating methods such as an electric range.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.4
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• pp.329-338
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• 1985

This study was undertaken in order to research formation of nitrosamine and its related compounds by salt concentration and nitrate content during Korean native soysauce fermentation. The results from measuring the changes of nitrite and dimethylamine content can be summerized as follows. As the nitrate content in used water was getting higher and the salt concentration was getting lower, the soysauce fermentation was abnormal. As the salt concentration was getting higher, the reduction of nitrate and formation of nitrite were delayed. But whether the nitrate content in used water was higher or not, the nitrite was continuously remained. An addition of ascorbic acid restrained the reduction of nitrate, and simultaneously, it could eliminate the nitrite effectively. As the nitrate content in used water, was getting higher, the content of dimethylamine was getting lower. Nitrosodimethylamine was detected from 0 to 261.34 ppb.

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.541-548
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• 2010

In this study, contamination levels of 7 N-nitrosamine were investigated in processed meat products (n=51), processed fish products (n=62), salted fish pickles (n=20), and beer and malt beverages (n=21) using a GC/PCI-MS/MS method. The limits of detection (LOD) of the N-nitrosamines ranged from 0.2 to 0.5 ${\mu}g$/kg. In addition, methods were used to estimate the recovery of 7 N-nitrosamines, which ranged from 84 to 112%. N-nitrosamines were detected in 89 (58%) out of 154 samples. The exposure of an entire population group to N-nitrosamines through food intake was estimated using the average body weight of the total population and average daily food consumption, to perform risk assessment based on reports of a national health and nutrition survey. The results indicated that the daily intake of N-nitrosamines over a life time was $4.92{\times}10^{-7}$ mg/kg b.w./day. The margin of exposure (MOE) for the general population, estimated using the benchmark dose lower confidence limit 10 ($BMDL_{10}$) of N-nitrosodimethylamine, was 208,939, which was found to be safe.