Studies on N-Nitrosamine of Korean Ordinary Soysauce

한국 재래식 간장의 니트로소화합물에 관한 연구

In recent years, the presence of N-nitrosamine, which was produced by the interaction of nitrite and secondary amine, in the fermented foods has been the subject of considerable interest and controversy. In this experiment, the levels of N-nitrosamine such as N-nitrosodimethylamine(NDMA), N-nitrosodiethylamine(NDEA) and N-nitrosodipropylamine(NDPA) in the Korean ordinary soysauce, which were added with ascorbic acid, sorbic acid, and sodium benzoate in the making of it were analyzed by low resolution mass spectrometry, and then the changes of dimethylamine(DMA), nitrate and nitrite nitrogen during the fermentation of it were observed. The contents of DMA nitrogen increased during the fermentation of Korean ordinary soysauce, continuously, but those of DMA nitrogen in the soysauce which had been added with ascorbic acid were inhibited, considerably, until the fermentation of 70days. The levels of nitrate nitrogen during the fermentation of Korean ordinary soysauee decreased, while those of nitrite nitrogen increased. The soysauce which had been incoporated with ascorbic acid in the making of it showed low amounts of nitrite. The concentration of NDMA in the control sample were 2.7 and $8.5{\mu}g/kg$ after the fermentation of 30 and 60 days, respectively, those of NDMA increased during the fermentation of Korean ordinary soysauce, but NDEA and NDPA in all of the soysauce were not detected. The samples were treated with ascorbic acid, sorbic acid, and sodium benzoate in the making of Korean ordinary soysauce were turn out to be effective in preventing the formation of NDMA. Inhibitive actions from food additives as above were, respectively, $82.2{\sim}87.0%$(ascorbic acid), $25.9{\sim}65.4%$(sorbic acid) an $13.2{\sim}63.5%$ (sodium benzoate) in comparison with control sample during the fermentation of Korean ordinary soysauce. NDMA contents were detected below $1.5{\mu}g/kg$ in the soysauce, which food additives were mixed to the pure NaCI in the brewing of it. Free amino acids such as glutamic acid, proline, and histidine were proved to be inhibiting the formation of NDMA during the fermentation of Korean ordinary soysauce. This might be due to the reaction above amino acids and nitrite by Van Slyke reaction.

예부터 우리나라 특유의 조미료로 상용되어온 재래식 간장을 제조함에 있어 강한 발암성 물질인 N-nitrosamine(NA)의 생성유래를 밝히고, 나아가서 이들의 생성을 억제시키는 방안의 일환으로써 몇몇 종의 식품첨가제를 이용하여 NA 생성에 미치는 영향을 검토하였고, 동시에 NA 생성과 밀접한 관계가 있는 유리아미노산, dimethylamine(DMA), 질산염 및 아질산염의 변화를 검색하였다. 간장숙성중 DMA 질소는 다소간 불규칙한 변화를 보이고 있으나 대체로 숙성과 더불어 증가하는 경향이었다. DMA의 억제효과는 ascorbic acid 및 sodium benzoate 처리구가 DMA생성을 숙성초기에 크게 억제시켰으나 숙성말기에는 큰영향을 미치지 못하였다. 질산염질소는 간장이 숙성되는 과정중 계속해서 감소하는 추세였으나, 반면 아질산염질소는 증가하였다. 아질산염의 생성을 최소화하기 위해서는 ascorbic acid가 가장 효과적인 식품첨가제였다. N-nitrosodimethylamine (NDMA)은 간장숙성중 증가하는 경향을 보여 대조구의 경우 숙성 30일에 $2.7{\mu}g/kg$, 숙성 90일에 $10.7{\mu}g/kg$검출되었다. 그러나 N-nitrosodiethylamine(NDEA) 및 N-nitrosodipropylamine(NDPA) 은 전혀 검출되지 않았다. 식품첨가제가 NDMA의 생성에 대한 억제효과는 시판식염으로 제조한 간장에서는 대조구에 비해 ascorbic acid 처리구가 $82.2{\sim}87.0%$, sorbic acid 처리구 $25.9{\sim}65.4%$ 및 sodium benzoate 처리구에서는 $13.2{\sim}63.5%$의 억제효과를 보였다. 그리고 순 NaCI로 제조한 간장중 NDMA의 함량은 ascorbic acid 처리구가 1.5㎍/㎏이하로서 대조구에 비해 NDMA의 생성이 크게 억제되었다. 간장중에 존재하는 유리아미노산이 NDMA의 생성을 억제시킨다는 것이 본 실험에서 밝혀졌고, 이중 특히 glutamic acid, proline 및 histidine이 주된 아미노산으로 추정되며 모델실험결과 간장중 유리아미노산을 제거할 경우 NDMA의 생성을 30.3%나 촉진시켰다.