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Effect of Glass Transition and Cross-Linking on Rheological Properties of Gluten: Development of a Preliminary State Diagram

¹Department of Food Technology and Nutrition, American University of Beirut, Beirut, Lebanon. ²Corresponding author. E-mail: toufeili@aub.edu.lb Fax: 961-1-744460. ³Center for Advanced Food Technology, Department of Food Science, Rutgers, The State University Of New Jersey, P.O. Box 231, New Brunswick, NJ 08903-0231.

The glass transition temperature of gluten at different moisture levels was determined by differential scanning calorimetry and mechanical spectrometry. The dynamic moduli (G′ and G″) of gluten with 10–40% moisture were measured as a function of temperature by pressure rheometry. At 10% moisture, gluten exhibited entangled polymer flow at 92–140°C and networking reactions at higher temperatures. At higher moisture levels, gluten experienced structured flow before networking cross-linking reactions. The onset temperature of the reaction zone was 120°C in 20% moisture gluten and 93°C at moisture levels of 30–40%. Softening of the vitrified network occurred at 184, 181, and 170°C in 20, 30, and 40% moisture gluten, respectively. A preliminary state diagram of gluten as a function of moisture and temperature was developed.