Cellulase-assisted release of secoisolariciresinol from extracts of flax (Linum usitatissimum) hulls and whole seeds

Extraction of secoisolariciresinol from seed hulls and whole seeds of flax was improved using an enzymatic step with cellulase R10 from Trichoderma reesei that allowed better yield as compared to β-glucosidase. The cellulase assisted extraction process was further optimised for different parameters such as duration and concentration of hydromethanolic extraction, duration of alkaline hydrolysis, pH, duration and incubation temperature as well as enzyme concentration. Best results were obtained using a method including the following successive steps: 16 h of 70% hydromethanolic extraction, 6 h of 0.1 M sodium hydroxide hydrolysis followed by a 6 h incubation with 1 unit ml⁻¹ of cellulase R10 in 0.1 M citrate–phosphate buffer pH 2.8 at 40 °C. Under these conditions, all forms of the main flax lignan were recovered as the aglycone form, i.e. secoisolariciresinol. Highest yields in secoisolariciresinol diglucoside (SDG) equivalent reached 7.72% of flaxseed hull (cv. Baladin) dry weight and 2.88% of whole seed (cv. Barbara) weight, thus allowing a significant improvement in comparison with published methods.