EFFECTS OF MOISTURE, SUCROSE, NaCl, AND ARABINOXYLAN ON RELAXATION IN WHEAT DOUGH AS MEASURED BY DMTA

Abstract

The effects of sucrose, NaCl, and arabinoxylan on the α-relaxation of wheat doughs with different water contents were investigated using Dynamic Mechanical Thermal Analysis (DMTA). DMTA measurements were made at the heating rate of 2°C/min from at least 30°C below the observed onset of the α-relaxation (glass transition) to at least 30°C above the transition. The glass transition temperature, T_g , was taken from the onset temperature of the decrease in storage modulus (G′). The frequencies used were 0.1, 1, and 5 Hz and amplitude was 16 μm. The storage modulus, G′, showed α-relaxation in all doughs with added ingredients. Added ingredients decreased the glass transition temperature of dough. The T_g of doughs with different ingredients decreased with increasing water content of doughs over the whole a_w range used (0.113–0.753). Also, the T_g increased with increasing frequency.

Keywords:

• DMTA
• Glass transition
• Wheat dough

ACKNOWLEDGMENTS

This study has been carried out with financial support from the Finnish Food Research Foundation, the Foundation of Tiura, the Commission of the European Communities, Agriculture and Fisheries (FAIR) specific RTD program, CT97–3609, Use of Wheat Water Extractable Arabinoxylans (WEA) to Improve Stability of Frozen Doughs and Quality of Bread, the University of Minnesota, Agriculture Experiment Station, Project 18–72, and the Institute of Food Technologist Marcel Loncin Research Prize. The study does not necessarily reflect the Commission's views and in no way anticipates the EC Commission's future policy in this area. The flour and flour analysis were kindly provided by Professor Jan Delcour, Katholieke Universiteit, Leuven, Belgium.