Dehulling crambe seed for improved oil extraction and meal quality

Crambe seed had low bulk density (328 kg/m(3)) due to thick hulls (0.23 mm) , which made up 21.2% of the seed weight. The mean seed diameter was 2.7 mm (SD +/- 0.2 mm); the thousand-grain-weight was 6.2 g. Dehulling improves o il extraction efficiency and facilitates the marketing of high-protein meal (>40% protein). The effectiveness of roller milling/aspirating and the eff ectiveness of impact milling/aspirating on dehulling crambe seed were studi ed and compared by analyzing the meat and hull fractions for oil and protei n contents and calculating material balances. Roller milling was more effec tive than impact milling. The optimal roller mill gap was 7/64 in. (0.28 cm ), and the optimal impact mill speed was 2,400 rpm generating 44.7 m/s tang ential speed. The optimal aspiration airflow was 1,970 ft(3)/min (55.7 m(3) /min). Roller milling/aspirating was projected to produce 46% protein meal at 12% moisture and 1% residual oil (typical of solvent extraction) or 42% protein meal at 12% moisture and 6% residual oil (typical of screw pressing most other oilseeds). Hand-dissected hulls contained 10.4% moisture, and 1 .2% oil and 8.8% protein on a dry basis, whereas the meats contained 8.8% m oisture, and 47.6% oil and 31.6% protein on a dry basis. Optimal roller mil ling/aspirating produced hulls with 8.1% oil and 11.4% protein and meats wi th 42.6% oil and 30.5% protein on a dry basis.