frictiondehulling

Friction dehulling is a mechanical method for removing hulls from seeds by frictional abrasion against rough, moving surfaces. It relies on the hull being more friable than the kernel, so repeated rubbing shears the hull away while largely preserving the inner seed. In typical equipment, seeds are conditioned to an appropriate moisture level and fed into a friction dehuller with intermeshing or counter-rotating rollers or discs. The frictional contact abrades the hull, and the detached hulls are separated from the kernels by screening or aspiration.

Applications and performance: This method is widely used for hull-containing seeds such as sesame and certain legumes. Dry or wet friction systems can achieve high hull removal while maintaining kernel integrity; effectiveness depends on moisture, seed size, and machine geometry. Some hull fragments or minor kernel breakage can occur if the process is too aggressive.

Advantages and limitations: Friction dehulling is robust, scalable, and relatively gentle on kernels compared with harsher methods, producing clean hulled kernels with low fiber. Limitations include energy consumption, dust generation, wear of abrasive surfaces, and the need for effective separation of hulls afterwards.

Related processes include pearling and other abrasive dehulling methods.