Stability of Catechin in Aqueous Solution with Coexistent Ascorbic Acid or Octanoyl Ascorbate and Organic Acid

概要

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The degradation kinetics of catechin in aqueous solution in the presence of L-ascorbic acid or octanoyl L-ascorbate, which was synthesized through the immobilized-lipase-catalyzed condensation of ascorbic and octanoic acids in acetonitrile, and of various organic acids were expressed by a first-order equation. The stability of catechin was reduced by the addition of ascorbic acid or octanoyl ascorbate at a concentration of 10 mmol/L, although the rate constant, k, for degradation in the presence of ascorbic acid or octanoyl ascorbate decreased with increasing citric acid concentration. Malic, lactic and sorbic acids were also effective for decelerating the oxidative degradation by ascorbic acid and octanoyl ascorbate, but their suppressive effects on the degradation of catechin differed between the solutions containing ascorbic acid and octanoyl ascorbate. This indicates that octanoyl ascorbate acts on catechin with a different mechanism from that of ascorbic acid.
2010-03-01