Betalains food sources

Betalains have recently regained importance due to continuing interest in natural food colorants. Currently, red beet is the only food source commercially exploited, although amaranth, Swiss chard, yellow beet, and cactus fruit represent promising... 

In addition to the pigment concentration in the respective food source, the color quality is of major importance for plant material quality assessment and selection during production and storage. Color quality also strongly affects consumer purchase decisions. Since red beet is still the sole betalain source exploited commercially, quality parameters have been developed for beet preparations. The most important one is the so-called color shade representing a ratio of two absorbance values, namely for betaxanthins and for betacyanins, respectively, A (at 535 mn)/A (at 480 nm). 

The betalains are confined to ten families of the order Caryophyllales20 The only foods containing betalains are red beet (Beta vulgaris), chard (B. vulgaris), cactus fruit (Opuntia ficus-indica) and pokeberries (Phytolacca americana). They also occur in the poisonous mushroom Amanita muscaria but this is not a normal food source. The importance of the betalains as colorants is confined to preparations from red beet. 

As for anthocyanins, betalains are found in vacuoles and cytosols of plant cells. From the various natural sources of betalains, beetroot (Beta vulgaris) and prickly pear cactus (Opuntia ficus indica) are the only edible sources of these compounds. In the food industry, betalains are less commonly used as natural colorants from plant sources than anthocyanins and carotenoids, probably related to their more restricted distribution in nature. To date, red beetroot is the only betalain source exploited for use as a natural food coloring agent. The major betalain in red beetroot is betanin (or betanidin 5-0-P-glucoside). Prickly pear fruits contain mainly (purple-red) betanin and (yellow-orange) indicaxanthin and the color of these fruits is directly related to the betanin-to-indicaxanthin ratio (99 to 1, 1 to 8, and 2 to 1, respectively in white, yellow, and red fruits)." ... 

Figure 6-31 Structure of Naturally Occurring Betalains in Red Beets. Source-. From J.H. Von Elbe and I.-Y. Maing, Betalains as Possible Food Colorants of Meat Substitutes, Cereal Sci. Today, Vol. 18, pp. 263-264, 316-317, 1973.

Apart from the derivatives of p-carotene, other pigments are the anthocyanins, the chlorophylls, cochineal, the betalaines, turmeric, caramel and riboflavin. In this account the historical background in brief, the chemistry of these pigments, their extraction from natural sources and their synthesis will be discussed. The present permitted natural substances and nature-identical synthetic materials (also described by the Food and Drugs Administration, the FDA, as colorants exempt from certification ) is quite small in number. Reference is also made to colourants no longer listed but which have an historical organic chemical significance such as for example brazilin and its relative haematoxylin. 

---