Flaxseed (Linum usitatissimum) meal, the main byproduct of the flaxseed oil extraction process, is composed mainly of proteins, mucilage, and phenolic compounds. The extraction methods of phenolics either commonly employed the use of mixed solvents (dioxane/ethanol, water/acetone, water/methanol, and water/ethanol) or are done with the aid of alkaline, acid, or enzymatic hydrolysis. This work aimed at the study of optimal conditions for a clean process, using renewable solvents and enzymes, for the extraction of phenolics and proteins from flaxseed meal. After a screening of the most promising commercial preparations based on different carbohydrases and proteases, a central composite rotatable design and a mixture design were applied, achieving as optimal results a solution containing 6.6 and 152？g of phenolics and proteins, respectively. The statistical approach used in the present study for the enzyme-enhanced extraction of phenolics and proteins from the major flaxseed byproduct was effective. By means of the sequential experimental design methodology, the extraction of such compounds was increased 10-fold and 14-fold, when compared to a conventional nonenzymatic extraction. 1. Introduction Flaxseed (Linum usitatissimum) meal is the main byproduct from the flaxseed oil extraction process, being primarily used as a ruminant feed. The meal is composed of three important fractions: proteins (over 300？g？kg？1), which are rich in arginine and glutamine; amino acids that are very important in the prevention and treatment of heart diseases and in supporting the immune system; mucilage (approximate content of 80？g？kg？1), which is a mixture of neutral arabinoxylans and rhamnogalacturonans, with good water-holding capacities and high viscosity; phenolic compounds, such as p-coumaric and ferulic acids, lignan secoisolariciresinol, which is presented glycosylated (Figure 1) and/or esterified with 3-hydroxy-3-methylglutaric acid to form oligomers. The content of secoisolariciresinol diglucoside in flaxseed is 2-3？g？kg？1, and about 10–40？g？kg？1 in defatted flaxseed powder [1–5]. Figure 1: Lignan secoisolariciresinol diglucoside. In humans and animals, secoisolariciresinol is transformed by the anaerobic intestinal microflora into the mammalian lignans, enterolactone, and enterodiol, which are capable of binding at low levels to estrogen receptors. Additionally, these lignans have antioxidant, hypocholesterolemic, and antiatherosclerotic activities and inhibit the development of type 1 and type 2 diabetes, and mammary, prostatic, and colonic tumors [3, 6–9]. Lignans
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