The decomposition of IV-nitrosamides was investigated in aqueous and organic solvents as a function of temperature and pH. In aqueous solvent, N-nitrosomethylpropionamide (NOMP) had maximum stability at pH 4.0 over the temperature range 4-50 °C. Further experiments also confirmed that IV-nitrosamides are much less stable than volatile IV-nitrosamines such as IV-nitrosopyrrolidine (N-Pyr) and dimethylnitrosamine (DMN). Thermal decomposition studies utilizing heating conditions commonly encountered in the pan frying of bacon and oven roasting of pork indicated that NOMP was degraded to the extent of 74-97% compared to 3-14% for N-Pyr and DMN. It was tentatively concluded that the major contribution of N-substituted amides, if present in foods, may be as precursors of IV-nitroso compounds formed by in vivo N-nitrosation reactions.It has been previously reported that free amines can readily react with fatty acids and triglycerides in model systems to form N-substituted amides (Kakuda and Gray, 1980a). It was concluded that these reactions could possibly take place in foods during processing and storage, thereby producing another chemical species capable of reacting with nitrite. The kinetics of N-nitrosation of these amides were studied in model systems (Kakuda and Gray, 1980b) and it was reported that the amide is rapidly Nnitrosated in acid environments, thus offering the possibility of in vivo formation of IV-nitrosamides. This paper reports the results of a kinetic study of the decomposition of IV-nitrosamides as a function of pH and temperature. The stability of these IV-nitroso compounds when subjected to thermal stresses such as encountered in the pan frying of bacon or oven roasting of pork is also reported. These studies were designed to establish whether such compounds could possibly be present in food systems since previous studies have established that IV-nitrosamides are unstable under neutral and alkaline conditions (Druckrey et al., 1967).EXPERIMENTAL SECTION Materials and Methods. IV-Nitrosomethylpropionamide (NOMP) and IV-nitrosopentylpalmitamide (NOPP) were prepared and purified as previously described (Kakuda and Gray, 1980a,b). Dimethylnitrosamine (DMN) was obtained from Eastman Kodak Co. (Rochester, NY) and IV-nitrosopyrrolidine (N-Pyr) from Aldrich Chemical Co. (Milwaukee, WI). All other chemicals were of reagent grade or better.Absorbance readings were recorded on a Shimadzu multipurpose spectrophotometer MPS 50 L and pH readings determined on a Model 26 radiometer fitted with a GK 2311 C glass electrode. Gas chromatographic analyses were performed on a Hewlett Packard 402 gas chromatograph equipped with a flame ionization detector and a glass column (6 ft X 3/8 in. i.d.) packed with 3%OV-101 on 80-100 mesh Chromosorb W. The samples were chromatographed isothermally at 90 °C with the flash heater and detector block at 140 and 160 °C, respectively.The nitrogen carrier gas flow rate was 20 mL/min. Decomposition of NOMP in Aqueous Solvent. Buffer Systems. The buffer systems for pH 2.0 and 7.0
