Color, pigments betalains

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). 

Beet toots contain both ted pigments (betacyanins) and yellow pigments (betaxanthins), known collectively as betalains. Generally, the betacyanin content of beets fat exceeds that of the betaxanthins. Of the betacyanins present, 75—95% is betanin [7659-95-2] (41) (EEC No. E 162), making it the principal pigment ia beet colorant. 

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. 

Dhillon, A.S. and Maurer, A.J., Evaluation of betalain pigments as colorants in turkey summer sausages, Poultry Sci., 54, 1272, 1975. 

Betalains are water-soluble nitrogen-containing pigments responsible for the red and violet (betacyanins class) and yellow (betaxanthins class) colors found in many flowers, fruits, and occasionally in vegetative tissues of plants of most families of the Caryophyllales order (except the Caryophyllaceae and Molluginaceae families, which have anthocyanins instead)." ... 

Betalains are N-heterocyclic water-soluble pigments deposited in vacuoles. Their common precursor is betalamic acid consisting of a 1,7-diazaheptamethin system, an extended Jt-electron system exhibiting a canary yellow color. Betalamic acid may condense with cyc/o-dopa to yield betanidin, the common precursor aglycon of the red betacyanins. Betanidin in turn may be glycosylated and/or acylated, yielding 29... 

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. 

Besides their interesting color application values, betalainic plants are also worthwhile from a nutritional standpoint. Research on this topic has recently been resumed with great scientific vigor in both in vitro and in vivo studies on red beets, amaranth, red-colored Swiss chard, red-violet pitahayas, and especially cactus pears. ° In the future, betalainic color crops will be benchmarked because of their pigment structure and quantity and also because of the individual and synergistic activities of their components such as colorless phenolics, amino compounds, peptides, proteins, and hydrocolloids. 

Pasch, J.H. and Von Elbe, J.H., Red and yellow pigments from betalaines hold promise as substitutes for colors banned by the FDA, Candy Snack Ind., 142, 32, 1977. 

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). 

Betalains are largely confined to higher plants belonging to species under families of the order Caryophyllales, although they are also found in some fungi [14]. The pigments may be found in flowers, roots, and fruits of suitable species. Betacyanins do not co-occnr with anthocyanins, which they resemble closely in color it has been specnlated that they may have similar functions [14]. 

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. 

Some potential interfering materials are other red pigments FD C Red No. 40, FD C Red No. 3, cochineal, and beet powder (betalain pigments). The presence of alternative colorants may be suspected if the /wis-max at pH 1.0 is high (550 nm, more typical of betalain pigments), or if a bright red coloration is found at pH 4.5 (potential presence of artificial dyes). 

Betalains, the pigments of the red beet, have found increased use as food colorants. This unit describes a multiple-component system using visible spectrophotometry to determine the concentration of the pigment components (i.e., betacyanins and betaxanthins) calculated in terms of betanin and vulgaxanthin-I, respectively (see Basic Protocol 1). The total pigment content (betalain) is expressed as the sum of betacyanins and betaxanthins. 

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