A Novel Feeding Mechanism for Hulling Extra-Large Confection Sunflower Seed with Shearing Rolls

Abstract

Consumer demand for extra-large (XL) confection seed is high and increasing, but plantability of XL hybrid seed poses a challenge in terms of mechanical seed delivery limitations and an inherent decrease in germination. To alleviate these shortcomings, planting hulled kernels have been proposed; however, gently removing the hull while preserving an intact, viable embryo is necessary. The objective of this study is to improve the hulling efficiency of shearing rolls through improved seed orientation control entering the rolls. Although the strain and force at hull rupture was greater at transverse versus flat orientation, unacceptable kernel damage (>50%) was observed in seed processed in a flat orientation. A grooved extension of the feed tray, together with a 45° inclination of the rolls, accomplished transverse seed orientation entering the rolls. The combined effect of roll surface, roll inclination, pass gap configuration, and seed moisture on hulling efficiency was evaluated. The highest intact kernel yield (74%) was obtained from rubber rolls positioned at a 45° inclination, 5.8% seed moisture, and a three-pass gap configuration (0.21, 0.21, 0.14 cm distance). Controlling seed orientation significantly improved hulling efficiency and did not negatively impact viability as germination remained above 90%.