Experimental studies on the N-nitrosamine formation in bacon during cooking.

The present study aimed to clarify the mechanism and conditions for carcinogenic N-nitrosopyrrolidine (NPYR) formation in bacon during the cooking process, analyzing the precursors of N-nitrosamines in various materials, including raw pork and spices. Results obtained are summarized as follows:1. When bacon samples were brought to 100°-200°C within 10 minutes, the amounts of NPYR formed from free proline via pyrrolidine (Pyr) were almost the same levels as those formed via N-nitrosoproline (NPRO). In contrast, when samples were heated at 225°C, the yield of NPYR via Pyr was apparently greater than that formed via NPRO.2. Concerning the precursors of N-nitrosamines in fresh pork samples, spermine, a polyamine, was found to range from 50-100mg/kg, while levels of other polyamines were less than 1/10 of the spermine level.3. With regard to the precursors of nitrosamines in spices used for preparing commercial bacon, it was found that only pepper contained such compounds among the various spices so far tested, viz., pyrroperine and Pyr were detected, and both compounds are precursors of NPYR. In addition, piperine and piperidine which form N-nitrosopiperidine after a nitrosation reaction were isolated. The rates of nitrosation of the aforementioned compounds under acidic conditions at 37°C and 100°C were also studied.