Resistance of Soya Beans to Compression

Nine varieties of soya beans from two harvest dates were tested at two compression speeds, three orientations and four moisture contents. Force-deformation data during compression were evaluated by elastic parameters identified by a new generalized cubic model that fit all data to a very high coefficient of determination. Increased moisture content resulted in decreased force and toughness at failure. The force to rupture when compressed perpendicular to the cotyledon division was higher than other orientations of compression but there was less deformation. Higher speeds of compression required greater force to rupture but with a lower deformation. Early harvest required less force with greater deformation. Generally, toughness did not appear to be a strong indicator of differences among treatments. Maximum tangent modulus and maximum secant modulus reduced with increase in moisture content and showed excellent separation of values for orientation, speed of compression and harvest date, especially at moisture contents in the range that soya beans will be harvested and handled. Since these values represent the elasticity in the region of compression prior to failure, they may be a better indication of the true ability to resist compression.