• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.115-120
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• 1974

Secondary amines are known as one of the precursors of nitrosamines which are potent carcinogenic compounds of man and animals. Nitrosamines are formed when both secondary amines and nitrite are present. The nitrites are occurred naturally in vegetables, fruits and many others, and frequently used in fish product as a color fixative or a preservative. In this paper, to know the formation of nitrosamines in fish meat, the changes of dimethylamine (DMA) content during the heat treatment such as drying, roasting and fish cake processing are discussed. The results showed that generally DMA increased considerably during heat processing. During drying, DMA in cuttle fish increased 16 times higher, while in Alaska pollack doubled than the fresh. In the roasted mackerel, the DMA content appeared 6 times higher than the fresh, while 9 times higher in canning. In fish cake from yellow corvenia, DMA increased 4 times higher than the fresh. On the contrary diethylamine and diphenylamine were not found in this experiment.

• Preventive Nutrition and Food Science
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• v.2 no.3
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• pp.197-201
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• 1997

To develop a rapid analytical method of dimethylamine(DMA) and trimethylamine(TMA) in fish, the contents of DMA and TMA in squid(Illex illecebrosus and Sepiell maindroni), cod(Gadus marcrocephalus) and plaice (Paralichthys olivaceus) by gas chromatographic (GC) and colorimetric method were determined. Recoveries for DMA in fish were 86.8~102.5% by GC and 74.2~94.5% by colorimetric method, while those for TMA were 93.0~101.1% by GC and 62.9~117.5% by colorimetric method. The contents of DMA and TMA in fish by GC were 29.7~325.3mg/kg and 145.6~356.0 mg/kg, respectively, and these by colorimetric method were 20.0~241.2mg/kg and 139.1~304.3mg/kg, respectively. The analysis of DMA and TMA in fishes by GC after the solvent extraction was simpler and faster and showed better recovery than colorimetric method.

• Rapid Communication in Photoscience
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• v.4 no.3
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• pp.63-66
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• 2015

When the molecule in the excited state is subject to prompt predissociation, it is quite nontrivial to obtain vibrational structure of the excited state in general. This applies to the case of photochemistry of dimethylamine (DMA:$(CH_3)_2NH$). When DMA is excited to its first electronically excited state ($S_1$), the N-H bond dissociation occurs promptly. Therefore, $S_1$ vibronic bands are homogeneously broadened to give extremely small ionization cross sections and heavily-congested spectral features, making infeasible any reasonable spectral assignment. Here, we demonstrate that the predissociation rate of the excited state could be significantly reduced by the NH/ND substitution to give the much better-resolved $S_1$ spectral feature, revealing the vibrational structure of the excited state of $DMA-d_1$ ($(CH_3)_2ND$) for the first time.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.19-23
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• 2003

Dimethylamine (DMA) is the immediate precursor of carcinogenic N-nitrosodimethylamine (NDMA). In vitro and in vivo experiments using whole strawberries, and garlic and kale juices were conducted to determine concentrations of DMA and trimethylamine (TMA) in foods and urine. Experimental diets [an amino-rich diet as nitrosatable precursors in combination with added nitrate-containing drinking water without (TD1) or with whole strawberries or garlic or kale juices (TD2, TD3 and TD4, respectively), or a diet of low in nitrate and amino (TD5) were incubated in simulated saliva and gastric juices at 37$^{\circ}C$ for 1 hour. We also studied the urinary excretion of DMA and TMA after consumption of the experimental diets (TD1~TD5). Urine samples were obtained for 18 hrs after consumption of experimental diets and concentrations of DMA and TMA were measured in the digested diet and urine. The DMA concentration after incubation in experimental diets (TD1~TD5) was 4.7$\pm$0.3, 6.7 $\pm$0.2, 7.9$\pm$0.2, 7.1$\pm$0.2 and 0.3$\pm$0.1 mg/kg, respectively. Urinary excretion of DMA (TD1~TD5) was 22.0$\pm$5.0, 28.3$\pm$4.3, 29.2$\pm$4.1, 27.4$\pm$4.5 and 20.4$\pm$3.1 mg/18 hr, respectively. Consumption diets with added strawberries or juices of kale or garlic increased urinary TMA and DMA, suggesting that those precursors were excreted and not converted to the carcinogen, NMDA.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.755-759
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• 2008

As a disinfection byproduct, N-nitrosodimethylamine(NDMA) formation was studied according to chlorine, nitrogen, and carbon composition related to monochloramine and dimethylamine(DMA) concentrations. The highest NDMA formation was observed when the dimethylamine/monochloramine ratio was close to 1, and the formation was rapidly decreased when the ratio was less or greater than 1. The formation of NDMA increased with increasing chlorine/nitrogen ratio indicating the chlorine is a limiting factor. A rapid disinfection byproduct was formed at 72 hour contact time in this study. As the previous researches, pH was a significant factor for the NDMA formation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.223-231
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• 1976

Dimethylamine(DMA) is known as an origin compound of dimethylnitrosamine which is responsible for carcinogenesis. It has been also reported that relatively large amount of DMA is distributed in fish muscle, particularly in salted and fermented fish. Tn this experiment, the degradation products of protein and trimethylaminoxide(TMAO) by the temperature conditions of $17^{\circ}C\;and\;27^{\circ}C$ in the course of anchovy fermentation with $22\%$ of salt were analysed, and the formation of DMA was discussed. Protein-N decreased through the whole fermentation period ill the conditions of $17^{\circ}C\;and\;27^{\circ}C$ whereas amino-N increased proportionally to the decrease of protein-N, and the increasing rate of amino-N was remarkably faster at $27^{\circ}C$ than at $17^{\circ}C$. Trimethylamine(TMA) gradually increased with the decrease of TMAO till 69th day of fermentation, hereafter tended to slightly decrease. It seemed that the difference in fermentation temperature affects on the formation of DMA and obviously on the variation of TMAO. Both DMA and TMA content were inversely varied with the TMAO content. Correlation coefficient of DMA to TMAO in quantitative variation was shown -0.811 at $17^{\circ}C$ and -0.865 at $27^{\circ}C$ of fermentation temperature respectively. The results suggested that the formation of DMA during fermentation of anchovy was attributed to the degradation of TMAO showing, contributorial ratio of 0.66 at $17^{\circ}C$ and 0.75 at $27^{\circ}C$ respectively.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.402-406
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• 2006

N-Nitrosodimethylamine(NDMA) formation was studied as a function of chloramine concentration at a fixed dimethylamine (DMA) concentration of 0.05 mM at pH 7 and 8. Regression equations were developed by molar ratio of chloramine to DMA. The NDMA formation was dependent on molar ratio(chloramine/DMA) and was different when the ratio is less or greater than 1. The formation of NDMA increased with increasing chloramine concentration and a linear correlation was examined between NDMA concentration and the ratio on a log scale. The developed regression was applied to previously reported data and relative errors ranged from -79 to 163%. Regression equations could provide a potential tool to predict NDMA formation for a simple and quick estimation in water supply systems.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.9-12
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• 1978

Contents of dimethylamine (DMA) in fresh fish muscle were analyzed by gaschromatography. DMA contents were in Pseudosciaena manchuria $10.367mg\%$, in Theragra chalcogramma $19.133mg\%$, in Sardinops melanosticta $22.833mg\%$, and in Scomber japonicus $26.300mg,\%$ respectively. Individual amines could not be separated with such a low content.

• Journal of the Korean Society of Food Culture
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• v.9 no.2
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• pp.125-130
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• 1994

This study was intended to observe the effect of the addition of soused shrimp(5%, 10%) and/or cooked glutinous rice flour(2.5%) on the changes of low molecular nitrogen compounds content of Kimchi during fermentation at $10^{\circ}C$ for 14 days. The pH, total acidity, free sugar, nitrite, dimethylamine(DMA) and volatile basic nitrogen(VBN) contents were measured. The nitrite contents were approximately 0.16 to 1.31 mg/Kg at the inital stage of fermentation. It was found that the nitrite contents of Kimchi samples with 10% soused shrimp$(S_2,\;GS_2)$ were relatively high among the Kimchi samples. However, nitrite was not detected after the stage of optimum maturity in all Kimchi samples. The dimethylamine(DMA) content of Kimchi samples were increased during the fermentation with increasing the soused shrimp concentration. Cooked glutinous rice flour enhanced the DMA production of Kimchi with soused shrimp. DMA content were 0.93-1.2 mg/kg at initial stage end 1.6-2.26 mg/kg at final stage of fermentation of the Kimchi with soused shrimp. As the fermentation period increased, the VBN contents of Kimchi samples with soused shrimp$(S_1,\;S_2,\;GS_1,\;GS_2)$ were apparently higher than those of Kimchi samples without it(C, G). Though the soused shrimp enhanced the volatile basic nitrogen production but cooked glutinous rice did not affected VBN production during Kimchi fermentation.