ABSTRACT
The anthocyanins are part of the very large and widespread group of plant constituents known collectively as flavonoids. Anthocyanins acylated with two or more aromatic acids are platyconin, cinerarin, gentiodelphin, and zebrinin. Color of anthocyanin-containing media depends on structure and concentration of the pigment, pH, temperature, presence of copigments, metallic ions, enzymes, oxygen, ascorbic acid, sugars and their degradation products, sulfur dioxide, and other factors. Hydroxyl groups, methoxyl groups, sugars, and acylated sugars have a marked effect on color intensity and stability of anthocyanins. Color intensification by copigmentation increases with increasing anthocyanin concentration and increasing ratio of copigment to anthocyanins. Self-association also occurs in concentrated “neutral” solutions and is affected by the type and concentration of anthocyanin. Increased concentration of anthocyanin(s) in these and other plant tissues intensifies their color and may enhance color stability through the phenomena of intermolecular copigmentation and self-association. Intramolecular copigmentation is responsible for the color stability of anthocyanins containing two or more aromatic acyl groups.
