Colorants, food betalains

The color of betalaines is barely affected by the pH range normally found ia foods. However, the dyes are heat sensitive, which places some limitations on their use as food dyes. 

Von Elbe, J.H., Stability of betalaines as food colors, Food TechnoL, 29, 42, 1975. Kimler, L. et al., Betalamic acid, a new naturally occurring pigment, J. Chem. Soc./Chem. Commun., 21, 1329, 1971. 

Betalains have shown strong antioxidant activities in biological environments such as membranes and LDLs," -" suggesting that the consumption of betalain-colored foods may exert protective effects against certain oxidative stress-related diseases (i.e., cancers) in humans. Beetroot has been used as a treatment for cancer in Europe for several centuries. The high content of betanin in red beetroot (300 to 600 mg/kg) may be the explanation for the purported cancer chemopreventive effects of beets. 

The documented use of betalain pigments as food colorants dates back at least one century, when inferior red wines were colored with betalain-containing juices (e.g., red beet juice). This common practice was, however, soon prohibited, and the application of betalain colorants was widely replaced by artificial dyes, which displayed better stability, at a lower price, and with higher purity. But in recent years the interest in natural food colorants has been renewed, mainly because of consumers concerns about the safety of some artificial colorants, which may be hazardous to human health (234). As a result, the number of permitted artificial dyes has been markedly reduced, and new efforts had to be made to develop natural food colorants (235). However, current legislation restricts the application of betalain colorants to concentrates or powders (E 162) obtained from aqueous extracts of beets (211). 

Vareltzis, K.R and Buck, E.M., Color stability and sensory attributes of chicken frankfurters made with betalains and potassium sorbate versus sodium nitrite, J. Food Protect., 47, 41, 1984. 

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)." ... 

The fortunate constellation of scientists at Wisconsin facilitated further achievements toward increasing pigment content in red beets. In a recurrent selection program, betalain contents of red beet crops were enhanced by 200%. This example should encourage both food scientists and plant breeders to join forces and invest in the improvement of promising color crops. 

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... 

Stintzing, F.C. et al.. Color, betalain pattern and antioxidant properties of cactus pear (Opuntia sp.) clones, J. Agric. Food Chem., 53, 442, 2005. 

Von Elbe, J.H. and Maing, I.Y, Betalains as possible food colorants of meat substitutes, Cereal Sci. Today, 18, 263, 1973. 

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). 

Jimenez Aparicio, A. and Gntierez Lopez, G., Production of food related colorants by cnlture of plant cells the case of betalains., Adv. Exp. Med. Biol., 464, 195, 1999. Berset, C., Proprietes fonctionelles des colorants alimentaires naturels, Ind. Alim. Agr., 1, 5, 1994. 

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. 

Betalain pigments have been tested on rodents by feeding 50mg/kg pure betanin, 2000 ppm betanine in the diet and several other conditions.11 No carcinogenic or other toxic effects were observed and the authors concluded that red beet extracts were safe as food colorants. 

Betalain colorants are well established in the food chain and will probably continue in a limited capacity. 

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