Formation of N-nitroso compounds during cooking of Japanese food.

N-Nitrosamines in several traditional Japanese meals, such as 'Nebemono', 'Ten-pura' and Kara-age', were analysed. No appreciable amount, or only trace quantities, of NDMA and NPYR could be detected in these meals. The effects of various gases on nitrosamine formation in dried squid have been examined at higher cooking temperatures and the highest yield of NDMA was observed by exposure to the gas produced by the combustion of kerosene, followed by that of city gas, while very low levels of NDMA were formed when samples were wrapped in aluminium foil or broiled in air or argon atmospheres. The principal precursor of NDMA in dried squid was found to be TMAO, which is abundant in the squid muscle and from which nitrosatable DMA can be produced during broiling at higher temperatures.