Vulgaxanthin-I and

Fig. 21 Calculation of vulgaxanthin-I and betanin s proportion of the absorption of beet root juice. Curve 1 Vulgaxanthin s proportion of the absorption. Curve 2 Betanin s proportion of the absorption. Curve 3 Betanin and vulgaxanthin without impurities. Curve 4 Fresh beet juice, including impurities. (From Ref. 216.)...

The concentrated extract is applied as a streak (S cm) on a cellulose plate (0.1 mm, Merck) and developed twice (2 x IS cm) with 2-propanol-ethanol-water-acetic acid (6 7 6 1) as the mobile phase. The plate is dried in a nitrogen stream and five sharply yellow bands (Rf- 0.66,0.S6,0.48, 0.43, and 0.36) are observed. The bands with values at 0.48 and 0.43 are tentatively identiHed as vulgaxanthin I and vulgaxanthin n, respectively. The violet betanin band appears at Rj= 0.21 and some trailing may be observed. For semipreparative isolation of betalains in beetroot, homemade cellulose plates (0.3 nun, Macherey Nagel 300) give similar results. 

Betanin is the main pigment of red beet. It is a be-tanidin 5-0- 3-glucoside. The betaxanthins have only the dihydropyridine ring in common. The other structural features are more variable than in betacyanins. Examples of betaxanthins are natural vulgaxanthins I and II, also from red beet (Beta vulgaris) ... 

FIGURE 13.7 Structures for the representative betalains vulgaxanthin I (betaxanthin) and betanidin (betacyanin). 

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. 

In the first protocol (see Basic Protocol 1), the maximum light absorption of betanin, the major betacyanin, and vulgaxanthin-I, the major betaxanthin, are measured. The betanin and vulgaxanthin contents are calculated using each pigment s 1 % absorptivity value A,%. The method takes into account small amounts of interfering substances. 

The following pigments were identified in admixture with other betaxanthins indicaxanihin (2), vulgaxanihin II (44), vulgaxanthin I (45), miraxanthin III (54), and betaxanthins derived from a-aminoadipic acid, valine, and leucine. 

The minor compounds shown are the amide, vulgaxanthine I (9 R = NH ) and the aldehyde, vulgaxanthine II (9 R = H). The compound (10), indicaxanthin, although not present in the betalaines, is structurally related and occurs in other colouring matters. 

Figure 28 Structure of betalain pigments from Beta vulgaris. (A) Betacyanin betanin (R = glucose). (B) Betaxanthins vulgaxanthin I (R = OH) and vulgaxanthin II (R = NH2)- (C) Betalamic acid.

Beet juice or beet extracts are known to contain other pigments (isobetanin, prebetanin, vulgaxanthin-II) besides betanin and vulgaxan-thin-I. The error that is introduced by calculating all betacyanins in terms of betanin and all be-... 

SAGUY I (1979), Thermostability of red beet pigments (betanine and vulgaxanthin-1) Influence of pH and temperature , J Food Science, 44, 1554-1555. 

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