Reaction of D‐arabino‐hexosulose with L‐lysine

Abstract

D-arabino-hexosulose, a product of oxidative degradation of hexoses, reacts with L-lysine forming light coloured intermediary products (premelanoidins) which are further converted into brown macromolecular pigments. The reaction of D-arabino-hexosulose is not autocatalytic contrary to that of sugars. The browning proceeds after a zeroth order reaction mechanism. The induction period was observed neither in premelanoidin formation, nor in browning reaction. Both the hexosulose-lysine interaction and the browning consisted of two steps, possessing different kinetic characteristics and reaction mechanisms. The two steps of reactions are isokinetic only at lower temperatures. The activation energies and the activation enthalpies of premelanoidin formation and of browning reactions are temperature-dependent and are lower than those of the formation of intermediary compounds and of browning reactions of sugars.

Sensory profiles of reaction products between amino acids and D‐fructose or D‐arabino‐hexosulose

“…The reaction of D-arabino-hexosulose with amino acids is much more rapid than that of original sugars or even that of furaldehydes which are subsequent sugar degradation products [4]. In addition to brown macromolecular pigments volatile flavour-active substances are produced as well, mainly by STRECKER degradation of amino acids as hexosulose possess a structure typical for STRECKER-active compounds [5].…”