Dielectric relaxations of frozen wheat doughs containing sucrose, NaCl, ascorbic acid and their mixtures

The effects of sucrose, NaCl, and ascorbic acid on dielectric relaxations o f frozen wheat doughs were investigated using dielectric analysis (DEA). Al l ingredients were dissolved in dissolved in distilled water used to prepar e wheat flour doughs to optimum consistency using a 10 g bowl Micro-Mixer. DEA measurements were made at a heating rate of 1 degreesC/min from -150 to 10 degreesC. Before the measurements. samples were equilibrated at -30 deg reesC for 15 min to allow maximum ice formation, and then cooled at 1 degre esC/min to - 150 degreesC. The Frequencies used were 0.1, 0.5, 1, 5, 10, 20 , 50, 100 and 1000 Hz. The dissipation factor (tan delta) of DEA shocked an alpha -relaxation (glass transition), two low temperature relaxations (bet a and gamma) and ice dissolution. Added markedly depressed the glass transi tion (T-g') and onset of melting of ice temperature (T-m'), probably becaus e of the higher conductivity of the frozen material, and the decreased tran sition temperatures of tile unfrozen solute phase. At che higher frequencie s, the alpha -relaxation coincided with melting of ice. and all relaxation temperatures (alpha, beta and gamma) increased with increasing frequencies. (C) 2001 Academic Press.