Degradation of L-Ascorbic Acid and Mechanism of Nonenzymic Browning Reaction

Abstract

L-Ascorbic acid, in an acid condition, was degraded to furfural with the formation of 3-deoxy-L-pentosone as an intermediate. Furfural and 3-deoxy-L-pentosone were isolated and identified as 2, 4-dinitrophenylhydrazone and bis-2, 4-dinitrophenylhydrazone, respec-tively. This acid-catalyzed degradation reaction took place without oxygen and under the storage or cooking condition of foodstuffs. It was shown that aldopentoses and 2-keto-L-gulonic acid themselves were not intermediates of the reaction. D-Araboascorbic acid was also degraded in the same way to furfural and 3-deoxy-D-pentosone. A mechanism for the non-oxidative degradation reaction of L-ascorbic acid, including the formation of 3-deoxy-L-pentosone and furfural, was proposed.