DisplayTitle

Effects of Micronization on Protein and Rheological Properties of Spring Wheat

¹Agriculture and Agri-Food Canada, Cereal Research Centre, 195 Dafoe Rd., Winnipeg, MB R3T 2M9, Canada. ²Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. ³Corresponding author. Phone: 204-474-8069. Fax: 204-474-7592. E-mail: watts@ms.umanitoba.ca ⁴Department of Food Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.

This research investigated the effects of micronization, at different moisture levels, on the chemical and rheological properties of wheat. A set of tests designed to analyze protein fraction characteristics and rheological behaviors were conducted on samples from four wheat cultivars (AC Karma, AC Barrie, Glenlea, and Kanata). After being subjected to infrared radiation at three moisture levels (as-is, 16%, and 22%), the seeds were milled to produce straight-grade flour. The protein fractionation test revealed significant decreases (P ≤ 0.01) in both monomeric proteins (from 54% of total protein in the control to 37% in the tempered micronized sample) and soluble glutenins (9.4–2.5%). There was a strong negative correlation (r = -0.98) between the percentages of monomeric proteins and insoluble glutenins. Total extractable proteins of micronized samples tempered to 22% moisture decreased 43.5% when compared with nonmicronized control samples using size-exclusion HPLC (SE-HPLC). Micronization had a significant effect on gluten properties, as seen from a decrease in water absorption (P ≤ 0.01) and dough development time (P ≤ 0.01). Results showed that micronization at 100 ± 5°C had detrimental effects on wheat flour gluten functionality, including a decrease in protein solubility and impairment of rheological properties. These phenomena could be due to the formation of both hydrophobic and disulfide bonds in wheat during micronization.