Factors Affecting Groat Percentage in Oat

Abstract

ABSTRACTThe groat percentage represents an important quality characteristic of oat (Avena sativa L.). Our objectives were to characterize mechanical factors of the oat dehulling process and the physical characteristics of the oat grain that affect groat percentage. Mechanical factors were determined with a compressed air dehuller. Physical characteristics of oat grain were evaluated from 10 genotypes grown at three locations with digital image analysis. Groat percentage as determined by hand dehulling was compared with mechanical dehulling. The strength and duration of mechanical stress required to separate the hull from the groat and the strength of the aspiration required to remove free hulls from the groats had significant effects on groat percentage results. Insufficient mechanical stress resulted in ineffective dehulling, but excessive stress resulted in groat breakage. Excessive aspiration removed groats as well as hulls, but insufficient aspiration left excessive hulls with groats. Groat percentage values obtained by hand dehulling or by mechanical means correlated well. Hand sorting of mechanically dehulled groats to remove hulls remaining after dehulling improved their correlation, indicating the importance of hand‐sorting mechanically dehulled oats. Test weight and oat size uniformity were highly correlated with groat percentage. Negative correlation between hulls remaining after dehulling with groat percentage suggested that heavier hulls, associated with lower groat percentage, were more difficult to remove by aspiration. Positive correlations between groat breakage during dehulling and groat percentage suggest that thin hulls provide less protection to the groat during dehulling, resulting in higher levels of breakage.