Role of proline and hydroxyproline in N-nitrosamine formation during heating in cured meat.

N-Nitrosamines are formed in a multi-step reaction of nitrite with free amino acids and amines in the meat products. The aim of this study was to determine the role of proline and hydroxyproline in N-nitrosamines formation during heating of cured meat. A lean meat model was used with different nitrite concentrations (0, 120, and 480mg/kg), and addition of proline and hydroxyproline (1000mg/kg), followed by heating at different temperatures. Volatile nitrosamines were analyzed with GC-TEA. The nitrosamine content never exceeded 10μg/kg and stayed <LOQ as long as the nitrite level of 120mg/kg was not surpassed. The importance of proline as a precursor for N-nitrosamine formation was confirmed. In contrast, hydroxyproline inhibited NPYR formation (N-nitrosopyrrolidine) because no traces were found after addition of hydroxyproline. NPYR formation was not related to nitrite, but was significantly influenced by temperature (⩾200°C) and proline. NDMA-presence (N-nitrosodimethylamine) in heated meat products was influenced by nitrite and temperatures >120°C.