A Dry Mechanical Method for Concentrating the Lignan Secoisolariciresinol Diglucoside in Flaxseed

dry mechanical process was evaluated for obtaining a hull-rich fraction from flaxseed. Flaxseed hulls (seed coats) are an excellent source of secoisolariciresinol diglucoside (SDG), a lignan with potential functional food applications, but flaxseed hulls adhere tightly to the embryo, making separation difficult. A Comitrol processor was used to mill the seed, followed by sieving and aspiration to obtain a hull-rich fraction from Neche and Omega flaxseed cultivars. As a result, the content of secoisolariciresinol diglucoside (nonfat, dry basis) increased from 12.9 and 14.3 g/kg in whole Neche and Omega seed, respectively, to 27.6 and 23.8 g/kg (weighted averages) in the hull-rich fractions. The significant (P<0.0005) inverse correlation between oil and SDG contents for cv. Neche suggests that oil content in dry-milled fractions is a useful indicator of secoisolariciresinol diglucoside content. Compared to similar reported processes, this was less effective at producing a hull-free embryo, but the Neche hull fraction contained much less fat (173 g/kg weighted average) than the other processes. The hull fraction appears to be a good source of SDG for functional food studies.