The less nitrite added to processed meat, the lower the levels of potentially carcinogenic nitrosamines formed in the products. The formation of nitrosamines can be reduced even further by adding e.g. erythorbic acid. These are some of the findings from a PhD project at the National Food Institute, Technical University of Denmark.
Nitrite can react with amines in meat to form nitrosamines. The group of nitrosamines includes both the so-called volatile and non-volatile nitrosamines. The majority of the volatile nitrosamines are known to be carcinogenic. However, knowledge about the non-volatile nitrosamines is limited both in terms of their occurrence and their significance to human health.
Since 1995 Denmark has had national provisions on the use of nitrite for preservation of processed meats e.g. bacon, sausage, ham and deli meats. The provisions specify that if these types of meat are to be sold on the Danish market, generally only 60 mg of nitrite per kg meat may be added, as opposed to the 150 mg nitrite per kg meat according to common EU legislation.
The Danish national provisions were obtained because there is an assumed relationship between the amount of nitrite added and the levels of nitrosamines formed. The rules are intended to ensure the lowest possible levels of nitrosamines in nitrite-treated meat.
More nitrite leads to higher levels of nitrosamines
In her PhD project at the National Food Institute, Susan Strange Herrmann has studied the role of added nitrite and other factors on the levels of nitrosamines formed in nitrite-treated meatballs and cooked sausages.
The results confirm that by adding more nitrite, higher levels of several nitrosamines are formed. The study also shows that the addition of erythorbic acid, which has the same effect as ascorbic acid or ascorbate, reduces the levels of several nitrosamines by up to 20-75%. However, several other tested additives had only limited effect on the formation of nitrosamines. Experiments also show that cooking the processed meat increases the levels of certain nitrosamines.
Significance to human health
The project also examined which volatile and non-volatile nitrosamines are present in meat products on the Danish market and in what quantities. In order to investigate the occurrence and formation of both volatile and non-volatile nitrosamines Susan Strange Herrmann developed a new analytical method that enables quantitative analysis of both groups of nitrosamines by the same method. Such a method has not previously been described.
From the results of a study based on this new method, Susan Strange Herrmann has estimated that the Danish population through their intake of processed meat on average is exposed to low levels of volatile nitrosamines, which have a known carcinogenic effect.
In addition, Danes are exposed to a significantly higher level of the non-volatile nitrosamines. The significance to human health of several of these non-volatile nitrosamines is however still uncertain and further research would be needed in order to establish their toxicity.
Susan Strange Herrmann’s PhD project: N-nitrosamines in processed meat products – analysis, occurrence, formation, mitigation and exposure, funded by the Ministry of Food, Agriculture and Fisheries.