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Mechanical Behavior of Oats: The Groat Effect

¹Dept. of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108. ²Corresponding author. Email: gfulcher@umn.edu. Phone: (612) 626-1220. Fax: (612) 625-5272.

To evaluate the mechanical behavior of groats with constant mass and moisture content, individual groats were compressed along the major axis between parallel flat plates. Compression versus tension testing was adapted easily to groats, which are weaker along the major axis. Regression of maximum apparent stress on moisture content suggested that the proportionality constant was a function of an undefined biological difference (UBD) among tested samples and the y-intercept depended on groat mass and UBD. No brittle-ductile transition in the range of 9–30% moisture was observed regardless of genotype. Groats in general tended to fail by plastic compression at low moisture content (9–10%). Groats at high moisture content (>12%) generally buckled and burst near the midpoint of the crease, suggesting higher stress around the crease regardless of genotype. Apparent maximum stress should be considered as an average for a genotype. Knowledge of specific groat characteristics (including but likely not limited to mass and moisture) and how they influence apparent mechanical behavior should lead to improvements in oat milling.