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.

The 22 kDa component of the white-skinned sweet potato (Ipomoea batatas L.) suppressed blood glucose elevation in the glucose tolerance test, although it has yet to be conclusively identified. In this study, we attempted to isolate and identify this component using an anion exchange resin column. Purification by weak anion exchange resin (TOYOPEARL DEAE-650M) separated an active fraction but could not isolate the active component. Purification by strong anion exchange resin (TOYOPEARL SuperQ-650M) isolated a component that was approximately 22 kDa, but it was not the active component. The active component, 22 kDa sporamin protein, was isolated by combining strong and weak anion exchange resin. These results showed that separation based on the difference in the adsorptive power of the ion-exchange resin was possible, and the component that suppresses blood glucose elevation is one of the components of sporamin with similar polymorphism.