Effect of Roasting and Boiling on the Content of Vicine, Convicine and L-3,4-dihydroxyphenylalanine in Vicia faba L.

The pyrimidine glycosides, vicine and convicine, are compounds of the genus Vicia, whereas their aglycone derivatives, divicine and isouramil, are responsible for favism occurrence, and L-3,4-dihydroxyphenylalanine (L-DOPA) is a nonprotein amino acid precursor of dopamine in healthy neurons. The present work evaluated the effect of thermal treatment, which consisted of roasting and boiling, on the content of vicine, convicine and L-DOPA in mature cotyledons of 10 varieties of Mexican Vicia faba L. and determined the concentration of glycosides and L-DOPA by high-performance liquid chromatography. The raw cotyledons showed 2.88-6.10, 0.63-1.68 and 0.28-0.44 vicine, convicine and L-DOPA, respectively. The 12 and 40% and 30 and 61% decrease in vicine and convicine content, respectively, were observed to be the effect of roasting and boiling the samples. L-DOPA was totally removed by both thermal processes. In all analyzed samples, vicine was the main compound; however, there were significant differences between varieties and thermal treatments. Practical Applications: Vicine and convicine glycosides are strongly implicated in favism, a hemolytic anemia in humans, and in poor performance of laying hens. There are reports of decreased egg weight, increase in the fragility of the yolk and a number of blood stains, and decreased fertility and hatchability of eggs. The characterization of new varieties of faba bean in their content of potentially toxic glycosides allows selection of those with the lowest possible content of such compounds. Also, the application of heat treatments that reduce glycosides will allow the use of seeds or flour to develop harmless food and feed ingredients.