The stability properties of golden beet and red beet pigments: Influence of pH, temperature, and some stabilizers

Abstract

Golden beet (Beta vulgaris var. lutea) color was found to contain 8 components, of which the most important seemed to be vulgaxanthin-I and -II. Purified vulgazanthin -I solutions are easily degraded at high temperatures. The stability is, however, strongly dependent on pH: the stability is best at pH values between 5 and 6, the poorest at low pH values, but at pH 7 the stability is better than that of betanin. Vulgaxanthin-I is more stable in the raw extract than in a purified solution. EDTA, even in ppm amounts, was found to improve the stability of betanin. The effect was dependent on pH value, being most efficient at pH 2.0 and 5.0. Stability of vulgaxanthin-I was not improved by EDTA. Tannin did not show stabilizing influence. Ascorbic acid was found to have an unfavorable influence on stability, especially in the case of betanin.

Betalain Stability and Degradation—Structural and Chromatic Aspects

“…Several studies reported a superior stability of betacyanins as compared to betaxanthins at room temperature (Sapers and Hornstein 1979) as well as upon heating (Aronoff and Aronoff 1948; Herbach and others 2004a), for example the half‐life value of thermally treated betanin was 11 times higher compared to vulgaxanthin I (Singer and von Elbe 1980). Additionally, vulgaxanthin I was found to be more prone to oxidation (Saguy 1979; Saguy and others 1984) and less stable than betanin at acidic pH values (Savolainen and Kuusi 1978). On the other hand, the same betaxanthin was proven to exhibit higher stability than betanin at pH 7 (Savolainen and Kuusi 1978).…”

“…Additionally, vulgaxanthin I was found to be more prone to oxidation (Saguy 1979; Saguy and others 1984) and less stable than betanin at acidic pH values (Savolainen and Kuusi 1978). On the other hand, the same betaxanthin was proven to exhibit higher stability than betanin at pH 7 (Savolainen and Kuusi 1978).…”

Natural Food Colorants

“…Under similar conditions, vulgaxanthin-I has an Ea of around 67 kJ mol-I [476], and is therefore more sensitive than betanin to thermal degradation. The thermal stability of the betalain pigments is greatest between pH 5.0 and 6.0 in the presence of oxygen [474,476,481] and between pH 4.0 and 5.0 in its absence [474,477]. The rate of degradation of betanin and vulgaxanthin-I is more rapid in model systems, suggesting a protective effect conferred by constituents in the natural system (e.g.…”

“…The use of betalain-producing cell cultures has facilitated the elucidation of enzymes involved in betalin biosynthesis and the influence of various environmental factors such as light, temperature, precursor availability, [474,[481][482][483]. Betanin may also yield isobetanin and/or decarboxylated betanin, their formation being favoured upon heating at pH 3.0-4.0.…”

Structural and chromatic stability of purple pitaya (Hylocereus polyrhizus [Weber] Britton & Rose) betacyanins as affected by the juice matrix and selected additives

“…However, the results obtained were in part contradictory. Stability of betanin, the major betalain of red beet, was reported to be impaired by ascorbic acid due to bleaching effects caused by hydrogen peroxide formation during ascorbic acid degradation (Savolainen & Kuusi, 1978). Additionally, reduced half-life time of betanin in the presence of 1000 ppm ascorbic acid was observed (Pasch & von Elbe, 1979).…”