Betanin stability

Pasch, J.H. and Von Elbe, J.H., Betanine stability in bnffered solntions containing organic acids, metal cations, antioxidants, or sequestrants, J. Food Sci., 44, 72, 81, 1979. 

S. Wybraniec, K. Starzak, A. Skopi ska, M. Szaleniec, J. Stupski, K. Mitka, P. Kowalski, T. Michalowski, Effects of Metal Cations on Betanin Stability in Aqueous-Organic Solutions, Food Sci. Biotech., 22(2) (2013) 353-363. 

Beet extract is also used as a colorant. Extract is sold as either a concentrate prepared by evaporating beet juice under vacuum to a total soHds content of 40—60%, or as a powder made by spray-dryiag the concentrate. Both products usually contain ascorbic or citric acid as a stabilizer, and a preservative such as sodium propionate. On a dry-weight basis, beet extract typically contains between 0.4 and 1.0% betanin, 80% sugar, 8% ash, and 10% cmde proteia. 

Herbach, K.M., Stintzing, F.C., and Carle, R., Stability and color changes of thermally treated betanin, phyllocactin, and hylocerenin solntions, J. Agric. Food Chem., 54, 390, 2006. 

Pedreno, M.A. and Escribano, J., Correlation between antiradical activity and stability of betanine from Beta vulgaris L roots under different pH, temperature and light conditions, J. Sci. Food Agric., 81, 627, 2001. 

Figure 6-32 Visible Spectra of Betanin at pH Values of 2.0, 5.0, and 9.0. Source From J.H. Von Elbe, I.-Y. Maing, and C.H. Amundson, Color Stability of Betanin, Journal of Food Science, Vol. 39, pp. 334-337, 1974, Institute of Food Technologists.

It has only recently been discovered that acylated betacyanins exhibit intramolecular co-pigmentation that may also lead to stabilization of the chromophor, betanidin (Schliemann and Strack, 1998), a phenomenon which is well-known for anthocyanins (Brouillard and Dangles, 1993). Esterification of the sugar moieties of betanin (betanidin 5-0-glucoside), gomphrenin I and bougainvillein-v with hydroxycinnamates leads to bathochromic shifts... 

Detailed studies on the stability of betanin in aqueous solutions have shown that the pigment is hydrolyzed on heating to betalamic acid (3) and cyclodo-pa-5-O-glucoside 53). The latter compound has been obtained on a preparative scale by base exchange of betanin with proline in the presence of dilute aqueous ammonia 43). 

Beets contain betanin as a colouring pigment and there remains some shade of red at almost any pH level. Because of their low heat stability, beets are mainly used in cold produced, aseptically filled beverages such as milk drinks. 

Red beet pigments are heat labile, especially in the presence of metals (e.g., Cu, Mn, Fe, Zn) and at temperatures above 121°C, betanin is rapidly destroyed. Copper is the most efficient catalyst for the breakdown. The color can be stabilized by sequestrants and/or antioxidants such as citric acid, sorbic acid, and ascorbic acid though ascorbic acid has also been shown to decrease the color stability of betanin in aqueous solutions. 

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