Non‐Enzymic Browning. Development of Chromophores in the Glucose‐Glycine and Sucrose‐Glycine Systems

SUMMARY The development of chromophores in the glucose‐glycine and sucrose‐glycine systems was examined. During the reaction a number of conjugated unsaturated carbonyl compounds develop, the quality present at any one time being greater as the reaction proceeds, until browning is well advanced. During this period, which follows the period of rapid pH fall and α‐amino N utilization, the fluorescence of the system increases, and the quantity of water‐soluble, non‐volatile compounds extraetable into various organic solvents increases. The pattern of extraction indicates the gradual formation of intermediates of greater dehydration and greater light‐absorbing properties from smaller molecules. The presence of sulfites slowed the rate of development of conjugated unsaturated carbonylic and fluorescent compounds, and of subsequent early browning, whereas in the presence of sodium pyrophosphate, their rates of production are increased. Chromophores appear to develop at a faster rate in the presence of iron than in its absence, but apparently by a mechanism different from that occurring with phosphates. It is suggested that the production of larger carbonylic N‐containing polymers from smaller carbonyl compounds, occurs in the sugar‐amino compound systems.