Betalain is a relatively newterm used to describe a class of water-soluble plant pigments exemplified by the red-violet betacyanins and yellow betaxanthins. (In a parallel fashion, flavonoids comprise the red-blue anthocyanins and the typical yellow flavonoids that some authors call anthoxanthins.) Betalains owe their name to the red beet (Betavulgaris), from which they were originally extracted, and they are not as widely distributed as flavonoids. Other foods containing betalains include chard, pokeberries, and Indian cactus fruits. The major red pigment of red beets is betanin, and their major yellow pigment is vulgaxanthin (Fig. 11).
Betalains are stable in the pH range 3.5–7.0, which is the pH range of most foods, but they are sensitive to heat, oxidation, and light.
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