Cereal Chem 41:39 - 46.  |  VIEW ARTICLE

Dehydro-L-Ascorbic Acid Reducing System in Flour.

T. Kuninori and H. Matsumoto. Copyright 1964 by the American Association of Cereal Chemists, Inc. 

A dehydro-L-ascorbic acid (DHA) reducing system in flour was demonstrated by determination of the reduction rate of DHA in flour extract in the presence of glutathione (GSH). DHA added to flour-water extract (1:2) to the extent of 80 p.p.m. with excess of GSH was reduced about 90% at pH 5.9 at 35 C. within 30 min. The molar ratio of DHA to GSH, in this reaction, was 1:2. The catalytic system was found to be specific to DHA and GSH when compared with that of D-isoascorbic acid or cysteine and thioglycolic acid. The reaction rate was maximum at pH 7.0. It was thermolabile, since it was inactivated in 5 min., 72% at 60 C. and 100% at 70 C. From these results the system was presumed to be enzymatic, similar to that found in fresh potato juice, pea seedling, and cauliflower.