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The garambullo tree (Myrtillocactus geometrizans) which grows in the deserts of Mexico produces a purple fruit. The pigments were extracted, identified, and evaluated for their stability at different temperatures and pH values and in the presence of iron and chromium. One percent citric acid or ascorbic acid was added as a stabilizer, and a mixture of both was also used. On the basis of their visible Light spectrum and chromatographic profile, the pigments were identified as betalains, which have a stability greater than that of red beet pigments and which are very stable at low temperatures. The pigment concentration was determined to be 214 mg/(100 g of dry weight). The energy of activation for bleaching of color was 87.09 +/- 8.53 J K-1 mol(-1) at pH 5.5. Ascorbic acid protects the red color even when it is exposed to drastic treatments such as sterilization. Metals decrease the stability of garambullo pigment; the effect of iron was greater than that of chromium. Garambullo pigment has the potential for use in food processing at low temperatures such as in the dairy industry for the production of ice cream and dairy drinks.