The lignan (+)‐secoisolariciresinol extracted from flax hulls is an effective protectant of linseed oil and its emulsion against oxidative damage

Secoisolariciresinol (SECO) is a natural antioxidant lignan accumulated in large amounts in the seedcoat of flax and retained in the flaxseed cake residue during linseed oil pressing. Here SECO was extracted and purified from flaxseed cake and assayed for its ability to prevent oxidation of linseed oil and an o/w emulsion containing linseed oil. For this purpose, an accelerated storage (Schaal oven) test was performed and SECO effectiveness was compared to that of two antioxidants commonly used in food and cosmetic products: α‐tocopherol (α‐TOCO) and butylated hydroxyanisole (BHA). In our hands, SECO addition, ranging from 50 to 500 μmole per kg oil, significantly decreased the production of both primary (conjugated dienes, CD) and secondary (thiobarbituric acid‐reactive substances, TBARS) oxidation products. This study evidenced that SECO is an effective stabilizer of linseed oil and its o/w emulsion and this protective effect outperformed both the natural α‐TOCO and the synthetic BHA antioxidants. In particular, SECO was the most effective in the protection of the o/w emulsion against secondary oxidation products, which makes it a potential alternative preservative for oily products in foods and cosmetics. Practical applications : The present study could lead to applications in the food and cosmetic industries for the stabilization of o/w emulsions. Addition of SECO to linseed oil, already rich in ω‐3, could also result in a new functional food with synergistic beneficial actions on human health. Secoisolariciresinol, a natural antioxidant lignan accumulated in large amounts in the seedcoat of flax is here presented as an effective protectant of both bulk oil and o/w emulsion against secondary oxidation products, which makes it a potential alternative preservative for oily products in foods and cosmetics.