[9] Organonitroso compounds serve as a ligands giving transition metal nitroso complexes.
[11] Nitrosyls are non-organic compounds containing the NO group, for example directly bound to the metal via the N atom, giving a metal–NO moiety.
Their presence in finished products has been tightly regulated since several food-poisoning cases in the early 20th century,[12] but consumption of large quantities of processed meats can still cause a slight elevation in gastric and oesophageal cancer risk today.
[13][14][15][16] For example, during the 1970s, certain Norwegian farm animals began exhibiting elevated levels of liver cancer.
[18][19] Stomach acid catalyzes nitrosamine compound formation and is the main location of the reaction during digestion.
[20] The formation process is inhibited when amine concentration is low (e.g. a low-protein diet or no fermented food).
[22][23][24] However, when 10% of the meal is fat, the effect reverses, and ascorbic acid markedly increases nitrosamine formation.
[20][25] Vitamin C and erythorbic acid are already commonly used in the meat industry because they enhance the binding of nitrite to myoglobin, encouraging the formation of the desired pink color.