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Gelation and Retrogradation Mechanism of Wheat Amylose
Department of Subtropical Bioscience and Biotechnology, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
* Author to whom correspondence should be addressed.
Received: 1 July 2011; in revised form: 24 September 2011 / Accepted: 27 September 2011 / Published: 10 October 2011
Abstract: The flow behavior, dynamic viscoelasticity, and optical rotation of aqueous solutions of wheat amylose were measured using a rheogoniometer and a polarimeter. The amylose solutions, at 25 °C, showed shear-thinning behavior at a concentration of 1.2%, but plastic behavior at 1.4 and 1.6%, the yield values of which were estimated to be 0.6 and 1.0 Pa, respectively. The viscosity of the wheat amylose increased a little with increase in temperature up to 10 or 20 °C at 1.2% or 1.4 and 1.6%, which was estimated to be a transition temperature. The elastic modulus increased with increase in concentration, and increased with increasing temperature up to 20, 25 and 30 °C, which was estimated to be a transition temperature, respectively, then decreased gradually but stayed at a large value even at high temperature (80 °C). A very low elastic modulus of the wheat amylose was observed upon addition of urea (4.0 M) and in alkaline solution (0.05 M NaOH) even at low temperature. The optical rotation of wheat amylose solution increased a little with decreasing temperature down to 25 °C, then increased rapidly with further decrease in the temperature. The mode of gelation mechanism of amylose molecules, which was previously proposed, was confirmed and a retrogradation mechanism of wheat amylose was proposed.
Keywords: wheat amylose; gelation mechanism; hydrogen bonding; intra- and intermolecular association
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Tamaki, Y.; Konishi, T.; Tako, M. Gelation and Retrogradation Mechanism of Wheat Amylose. Materials 2011, 4, 1763-1775.
Tamaki Y, Konishi T, Tako M. Gelation and Retrogradation Mechanism of Wheat Amylose. Materials. 2011; 4(10):1763-1775.
Tamaki, Yukihiro; Konishi, Teruko; Tako, Masakuni. 2011. "Gelation and Retrogradation Mechanism of Wheat Amylose." Materials 4, no. 10: 1763-1775.