魚粉における揮発性ニトロサミンの存在および生成 ＩＩ 魚粉の製造条件と揮発性ニトロサミンの生成

Abstract

Factors affecting the formation of volatile N-nitrosamines (VNA) in the preparation process of fish meals were examined. In the present sutdy, we prepared sardine meals in our laboratory, and test meal samples were exposed to gaseous NO2 in sealed flasks under different conditions. Results obtained are summarized as follows: 1. The amounts of VNA formed were found to be directly proportional to the NO2 con-centrations; in contrast, VNA levels were remarkably lowered by the increment of moisture con-tents ln the meal samples. Formation of nitrosodimethylamine (NDMA), nitrosopyrrolidine (NPYR) and nitrosothiazolidine (NTHZ) in the NO2-trcated samples increased upon raising the reaction temperature in a range from 80 to 140°C. However, when samples were heated at 150°C or above, the formation of NTHZ and NPYR lowered, particularly marked decrease was noted in NTHZ contents, whereas the amount of NDMA increased almost consistently 2. The VNA formation in NO2-treated samples were much influenced by the freshness or storage period of raw fish materials, viz., meals made from decomposed materials yielded fairly low levels of both NDMA and NTHZ, while NPYR contents increased. The amounts of NDMA and NPYR formed in the NO2-treated samples were proportional to the levels of trimethylam-inoxide and proline in the test meals, indicating that these compounds would be the principal precursors of respective VNA. 3. The VNA levels in the NO2-treated samples were found to decrease gradually during storage at 30°, 10°and even-10°C, and the higher the storage temperature, the decreasing rate was observed to be faster.