Nonenzymatic discoloration in dried cabbage. II. Red condensation product of dehydroascorbic acid and glycine ethyl ester.

The cherry red colour formed initially in the browning of freeze-dried cabbage has been studied using a model system consisting of dehydroascorbic acid (DHA) and glycine ethyl ester which produces a chromogen of similar colour characteristics. Elemental analysis, gel elution, and spectral studies indicated that the reaction takes place in equimolar proportions to give a dimeric, unsaturated condensation product, the probable structure of which is discussed. The chromogen is labile, hygroscopic, unstable in aqueous or acidic medium, and is light and heat sensitive. [See Journal of Agricultural and Food Chemistry (1968) 16, 529 for part I.]