ABSTRACT
As frequently mentioned in the literature, anthocyanins co-exist in equilibrium in four different forms. The pH conditions shift this equilibrium toward a variety of structural forms, with the direct consequences of color changes of these pigments.1 As a rule, at pH above 4, yellow compounds (chalcone form), blue compounds (quinoid base), or colorless compounds (methanol form) are produced. Anthocyanins have the highest stabilities at a pH between 1 and 2 since the flavylium cation is the most stable predominant form.
