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Physicochemical and Structural Characteristics of Flours and Starches from Waxy and Nonwaxy Wheats¹

¹Presented in part at the 2000 AACC Annual Meeting, Kansas City, MO. ²Food Research Program, Agriculture and Agri-Food Canada, Guelph, ON, Canada. ³Corresponding author. E-mail: abdelaale@em.agr.ca Phone: 519-829-2400 ext. 3111. Fax: 519-829-2600. ⁴Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada. ⁵Plant Biotechnology Institute, NRC, Saskatoon, SK, Canada. ⁶Canadian Grain Commission, Winnipeg, MB, Canada.

A waxy spring wheat (Triticum aestivum L.) genotype was fractionated into flour and starch by roller and wet-milling, respectively. The resultant flour and starch were evaluated for end-use properties and compared with their counterparts from hard and soft wheats and with commercial waxy and nonwaxy corn (Zea mays L.) starches. The waxy wheat flour had exceptionally high levels of water absorption and peak viscosity compared with hard or soft wheat flour. The flour formed an intermediate-strength dough that developed rapidly and was relatively susceptible to mixing. Analysis by differential scanning calorimetry and X-ray diffractometry showed waxy wheat starch had higher gelatinization temperatures, a greater degree of crystallization, and an absence of an amylose-lipid complex compared with nonwaxy wheat. Waxy wheat and corn starches showed greater refrigeration and freeze-thaw stabilities than did nonwaxy starches as demonstrated by syneresis tests. They were also similar in pasting properties, but waxy wheat starch required lower temperature and enthalpy to gelatinize. The results show analogies between waxy wheat and waxy corn starches, but waxy wheat flour was distinct from hard or soft wheat flour in pasting and mixing properties.