Kinetics of physico-chemical changes occurring during storage of gluten inthe vicinity of the glass transition temperature

The objective of this work was to evaluate the kinetics of water absorption , color and foaming changes of wheat gluten as a result of storage in the g lassy or rubbery state (up to 45 degrees C above Tg) and to analyze the occ urrence of specific temperature and moisture effects besides the glass tran sition. Rate constants were very low in the glassy state but highly increas ed in the rubbery state where water absorption increased, gluten browned, f oaming capacity decreased and foam collapse increased. Arrhenius plots of r ates of water absorption and color changes showed breaks, indicating the im portance of Tg. Estimated activation energies for color and water absorptio n changes in the rubbery state were lower than those around Tg. Empirical m odels developed to describe the observed changes indicated that besides the distance between the storage temperature and Tg, the interdependent effect s of moisture and temperature were also very important.