title: Probing thermal transitions and structural properties of gluten proteins using ultrasound.
abstract: OBJECTIVE
  To probe the thermal and structural properties of gluten proteins using ultrasound.
  
  
  METHODS
  A new ultrasonic approach for characterizing the quality of wheat gluten proteins is described. Low frequency (50 kHz) longitudinal ultrasonic velocity, v L, measurements were performed on gluten samples extracted from three wheat flours differing in protein content and in wheat endosperm hardness.
  
  
  RESULTS
  At room temperature, v L for gluten extracted from soft flowers (Fielder) was found to be (870 ± 92) m/s, while for gluten extracted from extra strong flours (Glenlea) it was found to be (1,940 ± 90) m/s. In the second set of experiments, which aimed at probing thermal properties of gluten proteins, the variation in the numerical value of v L propagating in the wet gluten was found to be substantial (about 1,000 m/s) when the temperature of the gluten was raised from 20 to 90 °C, and also when gluten from different flour types was investigated. A continuous structural phase transition was observed, which was different for glutens extracted from different flours. Upon cooling, the velocity also varied depending on wheat type.
  
  
  CONCLUSIONS
  These experiments demonstrate that ultrasonic velocity measurements can be used as a selection tool and study changes in properties of wheat proteins, particularly the thermal transitions that are critical to the quality of end products such as noodles, pasta, and bread. It was also shown that v L is sensitive to gluten class (strength or protein content), showing the potential of such measurements as an early-generation selection tool in wheat breeding programs.
authors.affiliation: Department of Applied Physics, University of Sharjah, Sharjah, PO Box 27272, United Arab Emirates.
authors.forename: H M
authors.initials: HM
authors.lastname: Elmehdi
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, MB R3T 2N2 Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Scanlon
authors.affiliation: Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 Canada.
authors.forename: J H
authors.initials: JH
authors.lastname: Page
authors.affiliation: Agriculture and Agri-Food Canada, 195 Dafoe Rd, Winnipeg, MB R3T 2M9 Canada.
authors.forename: M I P
authors.initials: MI
authors.lastname: Kovacs
keywords: Gluten proteins; Quality; Structure; Thermal transitions; Ultrasound