Demucilaging and dehulling flaxseed with a wet process

A continuous wet process for demucilaging and dehulling of flaxseeds was proposed to recover mucilage fraction and hull fraction from flaxseed. Mucilage was obtained by aqueous extraction and demucilaged flaxseeds were milled and fractionated by water separation in mixing tanks. Hull-rich, kernel-rich and an inseparable fraction were obtained with yields of 52.6, 22.3 and 12.7 g/100 g, respectively, when disk gap was set as 0.4 mm. The hull content of kernel-rich fraction and kernel content of hull-rich fraction were determined as 20.9 and 11.1 g/100 g, respectively. Although 11.5% oil, 15.3% protein and 9.6% secoisolariciresinol diglucoside (SDG) were lost during the demucilaging and dehulling of flaxseed, SDG was enriched in the hull-rich fraction and the inseparable fraction, while flaxseed oil in the kernel-rich fraction. Compared with dry processes, the proposed wet process is time-consuming and requires substantial amount of water. However, it is continuous and easy to scale up, and can be economical when an aqueous extraction of oil is used. It is also a good alternative for recovery of flaxseed gum and enrichment of SDG.