Hydration of gluten: a dielectric, calorimetric, and fourier transform infrared study.

The nature of the hydration of proteins and the subsequent implications for functionality is a matter of importance in both pharmaceutical and food applications. Most published studies rely on the use of one technique and attempt to characterize the system. Few studies have used combinations of techniques. In this paper we report on the use of infrared, dielectric, and calorimetric methods to examine the hydration process of wheat gluten. This has been the subject of considerable study by other techniques and has been well characterized by our group. Results show that in both the infrared and dielectric measurements there is a change in behavior at about 35% water content. This is also the water content below which lowering the temperature of the sample does not result in ice formation. We suggest that at this water content the protein amide groups are fully hydrated, and beyond this point addition of water results in protein dilution rather than further hydration.