Mechanical Behavior of Oats: Specific Groat Characteristics and Relation to Groat Damage During Impact Dehulling

ABSTRACTOat damage has negative effects on milling yield and finished product quality. Interrelationships among groat characteristics and mechanical behavior were analyzed to better understand groat damage caused by impact dehulling (ID). Regression of the natural logarithm (ln) of apparent stiffness (Smax) on the contents of ferulic acid, syringic acid, and moisture suggests that ferulic acid or perhaps diferulate cross‐links increase groat stiffness, and syringic acid or perhaps syringate derivatives and moisture decrease groat stiffness. Polymer cross‐linking decreases extensibility, and moisture (a plasticizer) softens polymers. Regression of ln of apparent toughness (T) on β‐glucan and protein content implies that both polymers increase groat toughness. β‐glucan is a cell‐wall polymer, and the cell wall is known to confer toughness. The location of these polymers (perhaps concentrated in the bran) may also confer toughness. Regression of ln(ID) on moisture content, starch content, and T/Smax suggests that moisture decreases impact damage (as does T/Smax), and starch increases damage. Starch may act like filler, increasing stiffness and damage. According to the ratio of T/Smax, groats must be tough but not too stiff for low levels of damage.