Cyanide detoxification methods in food: A review

Abstract

Cyanide is a toxic substance found in several tubers such as cassava (Manihot esculenta), wild yam (Dioscorea hispida Dennts), some cerealia and legumes. In the plants, it can be in the form of cyanogenic glycosides, acetone cyanohydrin, and hydrogen cyanide (HCN). Cyanogenic glycosides such as linamarin and lotaustralin belong to the product of secondary metabolism. The characteristic of cyanogenic glycosides is intermediately polar, water-soluble, and often accumulated in the vacuoles of plant cells. Acetone cyanohydrins are intermediates product from cyanogenic glycosides and cyanide acid in plant tissues. HCN, hydrogen cyanide, is a volatile and water-soluble compound. The toxic effect of cyanide in humans is inactivation of cytochrome oxidase, respiratory disorders, sore throat, dizziness, limpness, convulsions, and lethal effects. Cyanide can be removed by several processes before consumption. Methods such as peeling, washing, heating, drying, fermenting and chemical treatment are used to remove or reduce cyanide. The treatment can damage the structure of the cell and hydrolyzed the cyanogenic glycosides to acetone cyanohydrin and glucose by endogenous enzyme like linamarase. A second enzyme, hydroxynitril lyase, can dissociate acetone cyanohydrins to HCN, ketone and aldehyde compound. The maximum safe level for total cyanide in food is 10 ppm. This review aims at updating the available knowledge on the various detoxification cyanide in food.