As early as 1879 a pigment which possessed a yellow-green fluorescence had been discovered in milk and later in other sources as liver, heart yeast and egg white. The pigments which possess these fluorescence properties were designated as “flavins”
Composition
Riboflavin was named because of the similarity of part of its structure to that of the sugar, ribose, and because of its relation to the general group of flavins. In its pure form this vitamin is a bitter tasting, orange yellow, odourless compound in which the crystals are needle shaped. It dissolves sparingly in water to give a typical greenish yellow fluorescence. Though stable to boiling in acid solution, in alkaline solution it is readily decomposed by heat. It is also destroyed by exposure to light. Riboflavin is measured in terms of milligrams or micrograms.