Comparison of dielectric properties and non-enzymatic browning kinetics around glass transition

摘要

Dielectric properties of maltodextrin- and poly(vinylpyrrolidone)-based food models designed for studying non-enzymatic browning rates in the vicinity of glass transition were determined at 9 frequencies from 0.1 to 1000 Hz at temperature range from-- 100 to 150 deg C. Dielectric spectra of both materials showed a beta-relaxation, an alpha-relaxation and significant increase in dielectricity at temperatures above the alpha-relaxation. The alpha- and beta-relaxations exhibited water- and frequency-dependence. They also moved towards lower temperatures as non-enzymatic browning reactants were added. The relaxation above alpha-relaxation only showed a water-dependence. Dielectric analysis proved to be a sensitive method for detecting molecular mobility below the glass transition observed by differential scanning calorimetry. Dielectric properties of the food models did not, however, completely explain the previously observed differences in non-enzymatic browning rates of the different food models.