Freezing
is not always the best way to keep foods safely. Some
reactions are known to be accelerated in ice. Furthermore, some other
reactions that are not observed in solution are also promoted in ice.
We found that the formation of nitrosamines through the reaction of
an amine with a nitrite is accelerated in ice. Surprisingly, cyanide
is formed through the reaction of glycine with nitrite in ice but
not in solution. Amines are present in many kinds of foods. Nitrite
is present in vegetables and is used as a food coloring agent and
to inhibit the reproduction of Clostridium botulinum. The maximum amount of cyanide formed reaches a dangerous level,
and the intake of this formed cyanide in a few tens of cubic centimeters
causes some people to get headaches. These facts suggest that hazardous
compounds could be generated in frozen processed foods. We report
here the formation of cyanide and its possible formation pathway in
ice. Finally, we propose a way to prevent cyanide formation in food
under frozen conditions.