[Influence of microorganisms on the formation of nitrosamines].

The N-nitroso compounds synthesis from amine and nitrite contained in food is influenced by many factors: -the pH; -the temperature; -the amine basicity; -the presence of organic groups which catalyse or inhibit the reaction. The chemical nitrosation of the amino group takes place at pH between 2 and 4,5. At the near neutrality pH of most of food, this synthetis, cannot be realised. Under these conditions the nitrosamine occurence can be explained by the effect of microorganisms. We have studied the influence of moulds used in cheese making on the nitrosation reaction in a middle where nitrate and amino groups are found together. The middles are realised on caseine or curdled milk, and contained 150 mg/l of nitrate and 100 mg/l of piperidine. The nitrosopiperidine has been identified in all the middles studied. The results are discussed concerning the risk of nitrosamine formation of this type of food during the technological process.