Nitrosamine meat, detection

Nitrosamines are detected in variable amounts in many foods (Table 9.15). The most common compound is dimethylnitrosamine, which is also a most powerful carcinogen. Some activity has been ascribed to nitrosopiperidine and nitrosopy-rrohdine. In meat products cured and treated with pickhng salt, 30% of the samples contained ni-trosodimethylamine (NDMA 0.5-15 pg/kg) and 13% nitrosopyrrolidine (NPYR >0.5 pg/kg). About 25% of the cheese samples analyzed were contaminated (0.5-4.9 pg/kg). 

N-Nitrosamines in Cured Meats Other Than Bacon. The presence of N-nitrosamines in cured meats other than bacon has been the subject of several recent surveys (19,58,59). In general, the majority of the positive samples contained extremely low levels of N-nitrosamine, usually less than I yg/kg (19,58). This low level could, in part, be attributed to the discontinuation of the use of nitrite-spice premixes in the mid-l970 s (l 9). In the Holland study (59), the predominant N-nitrosamines detected were NDMA and N-nitrosomorpholine (NMOR) and, generally, values of 4 yg/kg were obtained for each N-nitrosamine. More correctly, these are presumptive N-nitrsoamine levels since mass spectral confirmation of their identities was not achieved. 

Volatile nitroso compounds were determined in hams processed in elastic rubber nettings by SPE and GC-CLD577. By a similar method A-n i tro sodi ben zy lamine (278b), a semivolatile nitrosamine, was determined in these products by SPE followed by GC interfaced to a nitrosamine-specific TEA-CLD detector the coefficient of variation was 10.6% at the 2.1 ppb level578. The nitrosamines detected in ham most likely originate from the amine precursors in rubber and from the nitrite commonly used in the meat curing process. 

Several nitrosamines, including N-nitrosopyrrolidine (NP), N-nitrosodimethylamine (NDMA), and N-nitrosodiethylamine (NDEA), have been detected at various concentrations in this food. Table lists some typical values for the concentrations of these compounds in cooked bacon and some other prepared meat products (14). Nitrosopyrrolidine has been generally found, especially in bacon, at much higher levels than NDMA or NDEA, and most attention has consequently been directed toward this compound (15, 16). 

A number of nitroso compounds, A-nitrosamines among them, are potent carcinogens. The most common carcinogenic nitrosamines, found mainly in protein food, are A-nitroso-dimethylamine (NDMA), A-nitroso-diethylamine (NDEA), A-nitroso-pyrrolidine (N-Pyr), and A-nitroso-piperidine (N-Pip). These compounds supposedly increase the risk of colon, rectum, stomach, pancreas, and bladder cancers. Nitrosamines are most prevalent in cured meats, but have also been detected in smoked fish, soy protein foods dried by direct flame, and food-contact elastic nettings. Dietary surveys indicated weekly mean intakes of these compounds amounting to about 3 pg per person (Anon., 1988 Cassens, 1995). In addition, the precursors of nitrosamines, especially nitrate, are abundant in some leafy and root vegetables (Table 14.1). 

In general, nitrosamines arise only in very low concentrations. Since some of these compounds are a great health hazard, they should be detectable below 0.1 ppm in food for human consumption. The same procedures are available for identifying volatile nitrosamines which have been described earlier for the analysis of aroma constituents (cf. 5.2). However, precautions should be taken during the isolation step. Isolation of nitrosamines should not proceed at low pH since an acid medium in the presence of residual meat nitrites promotes further de novo synthesis of nitrosamines. Since the isolated fraction of neutral volatile confounds, which also includes nitrosamines, is highly conplex in composition, reliable nitrosamines identification by gas chromatographic retention data is not possible. Additional mass spectrometric data are needed to verify the chemical structure. 

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