Continuous abrasive method for mechanically fractionating flaxseed

Both the flaxseed hull, which is rich in the lignan secoisolariciresinol diglucoside (SDG), and the embryo, which is rich in oil with high α‐linolenic acid content, are of interest for functional food use. A mechanical process for preparing hull‐and embryo‐rich fractions was developed and characterized. The process consisted of three pearlers, a sifter that yielded fines, and a gravity table that yielded final hull and embryo fractions. The SDG contents of fractions correlated inversely with oil content, showing that oil content indicated purity of both embryo and hull fractions and that the fines were essentially hull particles. Process performance depended on seed variety, moisture content, and feed rate; the best yields were 285 g hull +fines/kg for low‐moisture Omega flaxseed, and 470 g embryo/kg seed for low‐moisture Neche. Corresponding oil contents of those fractions were 28.8 and 47.4%, respectively. This process appears to be commercially feasible, provided it can be scaled up. A single stage was used to identify features that should be incorporated into a scaled‐up unit, for example a 7‐mesh screen in the pearler chamber rather than 6‐ or 8‐mesh, and use of an overhead feed inlet to the chamber to direct seed into the disk‐plate gap.