• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.1
• /
• pp.117-125
• /
• 2016

Nitrite and dimethylamine (DMA) are the immediate precursors of carcinogenic N-nitrosodimethylamine (NDMA). This study investigated the effects of nitrite and nitrate contents in Chinese cabbage on changes in NDMA, nitrite, nitrate, and DMA contents during storage of kimchi. Contents of nitrite in Chinese cabbage 1 (HNC), Chinese cabbage 2 (MNC), and Chinese cabbage 3 (LNC) were $47.54{\pm}1.07$, $10.12{\pm}0.31$, and $6.10{\pm}0.09mg/kg$, respectively. Kimchi were assigned to one of the following three groups: kimchi used HNC (HNK), kimchi used MNC (MNK), and kimchi used LNC (LNK). HNK had higher levels of nitrite and nitrate than those in MNK and LNK after storage for 10 days and 20 days. DMA and NDMA contents decreased in all kimchi during the storage period. HNK had higher NDMA content than LNK until 20 days of storage. These results suggest that the contents of nitrite and nitrate in Chinese cabbage have significant effects on the formation of NDMA in kimchi.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.9
• /
• pp.1302-1309
• /
• 2016

N-Nitrosodimethylamine (NDMA) is formed through reactions between dimethylamine (DMA) and nitrite. Jeotgal, a traditional Korean salted and fermented seafood, contains a large amount of DMA and is an ingredient of kimchi condiment. This study investigated the effects of amount and type of Jeotgal on changes in NDMA and its precursor contents during storage of kimchi. NDMA was found in all 23 Jeotgal samples, and DMA in nine salted and fermented shrimp samples showed levels ranging from 16.5 to 58.9 mg/kg (average of 30.9 mg/kg). The seven salted and fermented anchovy juice samples showed DMA levels ranging from 21.7 to 44.4 mg/kg (average of 34.5 mg/kg). Kimchi was assigned to one of the following five groups: kimchi without salted and fermented anchovy juice and salted and fermented shrimp (control), kimchi with small amount of salted and fermented anchovy juice (AK1), kimchi with large amount of salted and fermented anchovy juice (AK2), kimchi with small amount of salted and fermented shrimp (SK1), and kimchi with large amount of salted and fermented shrimp (SK2). SK2 had higher DMA content than SK1 during storage while AK2 had higher DMA content than AK1 after storage for 10 days. Nitrite contents of AK1 and SK1 were higher than those of AK2 and SK2 after storage for 20 days. NDMA content was significantly higher in SK2 than in SK1 after storage for 0 and 10 days, and NDMA content in AK2 was significantly higher compared to that in AK1 after storage for 0 days. The DMA and NDMA contents decreased in all kimchi samples during storage. The effects of amount and type of Jeotgal on DMA and NDMA contents were reduced after storage for 20 days. The results suggest that the content and type of Jeotgal have significant effects on formation of NDMA in kimchi.

• Korean Journal of Food Science and Technology
• /
• v.20 no.2
• /
• pp.125-132
• /
• 1988

Gulbis were made of raw Pseudosciaena manchurica by different salting methods and drying conditions. During the Gulbi processing, the contents of trimethylamine(TMA), dimethylamine(DMA) and formaldehyde(FA) were chemically analyzed and the distribution of fat was microscopically observed. The contents of TMA, DMA and FA in raw sample were 0.9mg, 3.19mg and 0.19mg per 100g, respectively. The TMA contents in Gulbi were rapidly increased to 24.82-76.32mg during drying, while the DMA contents in Gulbi were slowly increased and FA contents in Gulbi remained nearly unchanged. These changes were not influenced by the kinds of salt and salting methods. The formation rates of TMA and DMA were twice faster dried by the controlled condition than the natural condition. The fat in muscle moved to the skin layer through connective tissue with the laps of drying time. The extent of fat shifting was smaller salted by purified salt than by bay salt. The muscle tissue of Gulbi dried by the controlled condition had clearer spaces between white muscles than that of the natural condition. The muscle tissue of Gulbi salted with purified salt exsisted orderly, while the sample salted with bay salt was clumped.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.11 no.1
• /
• pp.13-18
• /
• 1978

The present study was conducted to elucidate the pattern in changes of trimethylamine oxide and related compounds in the muscle of Alaska pollack during drying, especially referred to formaladehyde and dimethylamine. Three kinds of dried samples of Alaska pollack, sun dried, hot-air dried, and salted-sun dried, were prepared and analyzed for their contents of trimethylamine oxide, trimethylamine, dimethylamine, and formaldehyde. The amount of trimethylamine oxide remained in the salted-sun dried sample was relatively higher than those in the other two samples. In the content of trimethylamine, the hot-air dried sample showed an exceedingly high value shelving forty-two times higher than the raw sample while the other two samples showed barely three to four times content based on the raw sample. The dimethylamine content in the hot-air fried sample was comparatively lower than those in the other two samples, the former marked about ten folds of the raw sample's and tile latter showed about fifteen folds, respectively. Refering to the content of formaldehyde, it decreased to eighty-three percent of initial content in the hot-air dried sample. On the contrary, it increased about two times initial content in the other two samples, respectively. As a tendency, the formaldehyde content appeared increased or decreased correlatively with the dimethylamine content, whereas the case was reverse for the trimethylamine content.

• Journal of Korean Society on Water Environment
• /
• v.25 no.1
• /
• pp.90-95
• /
• 2009

This study investigates the oxidative degradation of N-nitrosodimethylamine (NDMA), a probable human carcinogen, by advanced oxidation process (i.e., UV process). The experiments were performed with various pH, initial concentration, UV intensity, and addition of $H_2O_2$ or $TiO_2$ on UV process. The results showed that the direct UV photolysis was the most effective treatment method. The lower pH, intial concentration and higher intensity of UV stimulated higher NDMA removal. However, addition of oxidant ($H_2O_2$, $TiO_2$) slows down photochemical treatment of NDMA since the oxidant can filter out the UV light and block it to reach the NDMA molecules. Dimethylamine (DMA) and nitrite were found to be a major byproduct from NDMA oxidation. To evaluate the chronic toxicity effects of UV-treated NDMA on the growth of microalgae, "Skeletonema costatum", was studied as long term experiments. Results demonstrated that after the 13 days exposure the chronic toxicity was decreased about 15% with application of UV process on NDMA degradation.

• Toxicological Research
• /
• v.21 no.2
• /
• pp.179-186
• /
• 2005

Dimethylamine (DMA) is a widely used commodity chemical with few toxicity data. Groups of 10 male and female F-344 rats were exposed by inhalation to 0, 5, 10, 20, 40 and 80 ppm of DMA for 6 hrs/day, 5 days/week for 90 days. The changes of body weight, organ weight, hematology, clinical chemistry, and histopathological changes were evaluated after the exposure. As the results, the body weight was significantly decreased at 80 ppm in male and female rats (p<0.05). The absolute lung weight showed no statistically significant changes in any group. In contrast, the relative lung weight significantly increased at 80 ppm in male and female rats (p<0.05). Erythrocytes, mean cell hemoglobin, leukocytes, neutrophil, and platelet numbers were significantly increased in male and female at 40 or 80 ppm of DMA (p<0.05, p<0.01). In addition, the serum values of total protein, urea nitrogen were increased in male and creatine kinase, total protein were increased in female rats at 40 or 80 ppm (p<0.05, p<0.01). Histopathological examinations of the male and female lung samples showed slight hyperplasia and congestion at 80 ppm. Taken together, our study revealed that maximum tolerated dose of DMA would be over 40 ppm.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.4
• /
• pp.245-253
• /
• 1979

Trimethylamine and dimethylamine contents of salted, hot-air dried, sun dried and boiled-dried samples of three commercial fishes, common mackerel, gizzard-shad and sardine, were analyzed and quantitatively compared at two different temperature conditions. The formation of both secondary amines was more rapid at $25^{\circ}C$ than at $10^{\circ}C$. And the content of dimethylamine in small sardine was comparatively higher than that in the other samples at both temperatures. Residual amounts of trimethylamine oxide of Halted common mackerel, gizzard-shad and boiled-dried small sardine were relatively higher than those of the other samples. Trimethylamine contents of sun dried samples were relatively higher than in the other samples, while those of boiled-dried small sardine was comparatively lower than those of the others. Dimethylamine content of sun dried samples were higher than those of the other samples, whereas those of boiled-dried small sardine and salted common mackerel were comparatively lower than those of the other samples.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.4
• /
• pp.390-393
• /
• 2005

N-nitrosodimethylamine (NDMA), a potent carcinogenic, has recently been observed at drinking water supply systems in USA and Canada. The NDMA formation was studied as a function of chloramine concentration (0.001-0.1 mM) at a fixed dimethylamine (DMA) concentration of 0.05 mM at different initial pH (6, 7, 8). It was found that the NDMA formation rate varied with pH values. The formation of NDMA increased with increasing chloramine concentration and showed maximum yields of 2.4% and 1.6% at pH 7 and 8, respectively. A good correlation ($r^2>0.99$) was observed between the molar ratio (chloramine/DMA) and NDMA formation at pH 7 and 8. Linearity of the NDMA formation appeared to be related to chloramine concentrations.

• Journal of Food Hygiene and Safety
• /
• v.13 no.3
• /
• pp.274-277
• /
• 1998

The study was focused to investigate the effect of nitrosodimethylamine (NDMA) formation due to nitrosamine (NA) precursor and/or inhibitor addition to Kimchi during the fermentation of Kimchi at room temperature ($16{\pm}2^{\circ}C$). The addition of nitrite and dimethylamine (DMA) to Kimchi showed the average 32-fold ($21.3{\sim}113.9\;\mu\textrm{g}/kg$) and 9-fold ($1.3{\sim}40.3\;\mu\textrm{g}/kg$) higher NDMA formation than control ($O{\sim}5.6\;\mu\textrm{g}/kg$), respectively. Also, the addition of both nitrite and DMA resulted in the increase of NDMA formation to average 42-fold ($39.4{\sim}155.7\;\mu\textrm{g}/kg$) higher than control. On the other hand, the addition of 4 ruM ascorbic acid to Kimchi with nitrite and DMA inhibited the formation of NDMA down to 71.3% of control. However, the addition of cysteine and erythorbic acid affected no inhibition to NDMA formation during the test. The addition of sodium sulfite increased NDMA formation. Accordingly, this showed that the amount of ascorbic acid generated during Kimchi fermentation played an important inhibition role for NA formation.

• Journal of environmental and Sanitary engineering
• /
• v.9 no.1
• /
• pp.76-88
• /
• 1994

This study was carried out to investigate contents of nitrosamine precursors such as trite and dimethylamine( DMA ) in some foods. The diazo and Cu- dithiocarbamate melt were used for determination, respectively. The major affecting factors of Nnitrosodimethylamine( NDMA ) formation such as pH, contents of DMA and NaNO$_{2}$, other chemicals, and UV- ray in beverage were investigated in vitro. The contents of nitrite in meat sausage and meat ham were 6.44 ∼ 18.66ppm and 12.85- 39.95pp% respectively, And extremely low level was detected in a certain kind of fish sausage. The contents of DMA in meat sausage meat ham and fish sausage were 3.34∼15. 85ppm, 1.20∼7.10ppm and 7.38∼12.28ppm, respectively. The optimum pH for NDMA formation in vitro was 3.0. NDMA formation was rapidly occurred at high temperature and formed above 80% within 1 hour reaction. The formation of NDMA was increased in proportion to the concentration of DMA and the square of the nitrite concentration. 0.1 M of sodium citrate, sodium tartarated and sodium taiocyanate enhanced NDMA formation. But sodium chloride did not affect. However, 0.3M of ascorbic acid, erythroid acid, ascorbic, palmitate and propy, gallate inhibited NDMA formalion approximately 78%,81%,86% and 85%, respectively. Cow milk and soybean milk inhibited 35 ∼47% of NDMA formation but orange juice and apple juice enhanced 15 ∼64% of NDMA formation. The peak in HPLC for NDMA disappeared by irradiation of UV to prior formed NDMA This result suggest that NDMA was destroyed by UV irradiation.