Reaction of glucose or galactose was performed in arginine solution or phosphate buffer (pH 7.0) using a batch reactor at 110 °C. The yields of products, pH, and absorbances at 280 nm and 420 nm were measured during the reaction. Fructose, mannose, and allulose were formed from glucose; tagatose, talose, and sorbose were done from galactose. The reaction proceeded more rapidly in arginine solution than in phosphate buffer. In arginine solution, yields of fructose and tagatose were 20% and 16%, respectively, after 30-min reaction; in phosphate buffer, they were 14% and 10%, respectively. However, in both reaction media, the pH drop and increase in absorbances continued even after the yield became almost constant. The absorbance increased particularly in the latter half of the reaction due to formation of browning products. Therefore, to avoid browning, the reaction should be stopped as soon as possible after the yield approaches its maximum value.

Molecules in foods and food ingredients exist in a variety of states, each of which has a different susceptibility to chemical and physical change. A model was proposed for the change in behavior over time based on the assumption that the free energy of activation in relation to the rate constant obeyed a Gaussian distribution. This model could well explain the unique behaviors observed in the thermal inactivation of immobilized enzymes, formation of aldehydes from lignin by alkaline nitrobenzene oxidation, autoxidation processes of microencapsulated lipids, flavor release from microcapsules, and desorption of proteinaceous deposits fouled on stainless steel surfaces.