• Culinary science and hospitality research
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• v.11 no.4 s.27
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• pp.1-13
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• 2005

This study analyzed the levels of N-nitrosamine(NA) and its precursors such as nitrite, nitrate, dimethylamine and trimethylamine in 10 samples of mollusk fish, 4 samples of crustacea fish and 11 samples of shellfish from fish distributed in a local markets. Mollusk fishes had nitrite concentrations ranging from non-detectable(ND) to 9.4 mg/kg, crustacea fishes ND to 8.8 mg/kg, and shellfishes ND to 4.3 mg/kg. Nitrates in mollusk fishes ranged from ND to 19.3 mg/kg, crustacea fishes 4.1 to 79.9 mg/kg, and shellfishes 1.5 to 61.9 mg/kg. DMK concentrations were 11.2 to 551.4 mg/100g in mollusk fishes, 44.4 to 79.9 mg/100g in crustacea fishes, and 1.3 to 5.9 mg/100g in shellfishes. TMA concentrations in mollusk fishes, crustacea fishes, and shellfishes were 10.3${\sim}$292.4 mg/100g, 35.5${\sim}$90.3 mg/100g, and 2.3${\sim}$17.1 mg/100g respectively. Only N-nitrosodimethylamine (NDMA) was detected for NA in fish distributed in local markets. NDMA contentrations ranged from ND to 41.4 ${\mu}g/kg$ in mollusk fishes, 3.0 to 47.3 ${\mu}g/kg$ in crustacea fishes, and 1.7 to 12.1 ${\mu}g/kg$ in shellfishes.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.279-289
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• 2018

N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and $pK_a$ values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor's prior chloramination.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.321-329
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• 2003

In order to provide data on N-nitrosamine (NA) and sanitation in fish available in domestic markets, this study analyzed the levels of NA and its precursors in 9 samples of sea breams and yellow croakers, 12 samples of red-flesh fish, 38 samples of white fish, 5 samples of Alaska pollacks and cod, and 8 species of imported fish. Sea breams and yellow croakers had nitrite concentrations ranging from non-detectable (ND) to 7.4 mg/kg, red fish ND to 5.3 mg/kg, white fish ND to 18.7 mg/kg, Alaska pollacks 0.3 to 2.2 mg/kg, and imported fish from 0.4 to 12.8 mg/kg. Nitrates in sea breams and yellow croakers ranged from 1.2 to 41.19 mg/kg, red fish 0.6 to 26.1 mg/kg, white fish 4.3 to 75.9 mg/kg, Alaska pollacks 0.4 to 3.1 mg/kg, and imported fish ND to 16.0 mg/kg. DMA concentrations were 69.8 to 219.9 mg/l00 g in sea breams and yellow croakers, 4.1 to 336.3 mg/l00 g in red fish, 1.3 to 331.9 mg/l00 g in white fish, 15.7 to 312.3 mg/l00 g in Alaska pollacks, and 1.0 to 71.8 mg/l00 g in imported fish. TMA concentrations in sea breams and yellow croakers, red fish, white fish, Alaska pollacks and imported fish were 43.8∼496.2, 12.3∼127.0, 2.0∼525.9, 15.4∼122.4, and 4∼70.6 mg/l00 g, respectively. For NA in fish distributed in local markets, only N-nitro-sodimethylamine (NDMA) was detected, and its concentrations ranged from 4.7 to 73.7 $\mu\textrm{g}$/kg in sea breams and yellow croakers, 2.2 to 56.5 $\mu\textrm{g}$/kg in red fish, ND to 143 $\mu\textrm{g}$/kg in white fish, 3.8 to 33.3 $\mu\textrm{g}$/kg in Alaska pollacks, and 2.1 to 102.2 $\mu\textrm{g}$/kg in imported fish.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.378-383
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• 2002

The aim of the study was to analyze N-nitrosamine (NA) and its precursors in serveral fermented foods which were treated with nitrite, thiocyanate and ascorbic acid under simulated gastric digestion. Every analyzed sample contained nitrate, with levels ranging from 0.3 to 1.3 mg/kg, but nitrite was present at very low levels of less than 0.3 mg/kg. And other precursors of amines such as dimethylamine and trimethylamine were detected less than 0.5 mg/kg in every samples. N-nitrosodimethylamine (NDMA) was detected in the levels of <0.5 ∼ 2.7 ug/kg in soy sauce,1.5∼3.1 ug/kg in soybean paste and <0.5∼1.8 ug/kg in beer, while NDMA levels increased by 1.1∼4.5 times in the fermented foods which were digested under simulated gastric conditions.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.94-100
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• 2002

This work was performed in order to examine the effect of nitrite, thiocyanate and ascorbic acid on formation of N-nitrosamine(NA) in kimchi, fermented anchovy and shrimp under simulated gastric digestion, in vitro. The contents of nitrate were 10.7~24.5 mg/kg in kimchi, 1.5~5.6 mg/kg in fermented anchovy, 1.0~2.0 mg/kg in fermented shrimp and those of nitrite were average 0.3 mg/kg in all analyzed samples. Dimethylamine and trirmethylarnine contents were 4.9~l5.4 mg/kg, 0.6~0.8 mg/kg in kimchi, 3.3~4.0 mg/kg, 1.9~2.8 mg/kg in fermented anchovy, 30.3~177.9 mg/kg, 4.4~21.3 mg/kg in fermented shrimp, respectively. The contents of N-nitrosodime -thylamine(NDMA) were in the range of 0.8~6.9 $\mu\textrm{g}$/kg in kimchi, 0~l.2 $\mu\textrm{g}$/kg in fermented anchovy and 0~0.9 $\mu\textrm{g}$/kg in fermented shrimp. After simulated gastric digestion, NDMA was increased about 1.5 times in all sample. In every nitrite added samples, the contents of NDMA were increased by 183.1 times in fermented shrimp and were detected 192.4 $\mu\textrm{g}$/kg and 220.9 $\mu\textrm{g}$/kg when it was treated with 4 mM and 8 mM of nitrite, respectively. NDMA, when above samples were added 8 mM nitrite and 6.4 mM thiocyanate, was increased about 1.5 times than control samples. The formation of NDMA was inhibited by 49.9~92.4% in all samples added 12.8 mM ascorbic acid compared with the control sample.

• Korean Journal of Food Science and Technology
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• v.11 no.1
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• pp.32-41
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• 1979

To clarify the formation of secondary amines in Korean native soysauce, periodical changes during 90 days aging were investigated. The results were as follows; 1. The average content of secondary amines in Korean native meju was 20.86 ppm $(7.25{\sim}50.76{\;}ppm)$ as dimethylamine(DMA), higher than modified meju(artifcial lyinoculated Aspergillus oryzae). Especially, the high amount was detected in severely deteriorated meju. 2. Cooked soybean, wheat, barley and rice contained 1.28, 0.57, 0.34 and 0.35 ppm of secondary amines, respectively. The more amounts were detected in koji, the respective contents in soybean, wheat, barley and rice koji were 2.63, 1.09, 0.64 and 0.54 ppm. 3. The new formation of secondary amines was not recognized in normally fermented Korean native soysauce during 90 days aging. 4. Secondary amines were formed below 18% sodium chloride under dark condition during soysauce aging, but not formed at 14% under sun-light condition. 5. The modified soysauce, prepared with modified meju, did not contain the newly synthesized secondary amines at 14% sodium chloride under sun-light condition during 30 days aging. 6, Drying of meju and boiling of soysauce did not affect the evaporation of secondary amines.