An approach to the characterization of betanine oxidation catalyzed by horseradish peroxidase.

摘要

Betalains are plant pigments which are used as natural food colorants. Factors influencing the stability of betalains have important implications for their commercial use as dyes. Horseradish peroxidase (EC 1.1.11.7) catalysed oxidation of betanine[betanin] (isolated from beetroots obtained from a market in Spain) is complex. The presence of at least 3 kinetically related absorbent species in the reaction mixture is postulated. Analysis by HPLC confirmed the presence of several reaction products.During the course of the reaction, a red intermediate and several yellow products, presumably of a polymeric nature, are generated, betalamic acid being one of the final products. Even in the absence of enzyme, the reaction, once initiated, continued, yielding betalamic acid as a final product. The chemical nature of the intermediate product and the possible reaction mechanism are discussed.