Linseed Extract

Lignan grades are quoted on secoisolariciresinol diglucoside by HPLC at 20, 35, 40 percent and higher, with the analytical method stated because colourimetric total lignan figures run higher on the same material. Linseed gum is graded on viscosity at a defined concentration and temperature, on gel strength where relevant, and on colour, with decolourised grades traded at a premium for use in pale products. Protein preparations are graded on protein content, from a screened meal flour at 35 to 45 percent up to an isolate above 80 percent.

Cutting across these, the starting material matters: brown and golden linseed differ in colour contribution rather than in composition, and whether the seed was cold pressed or solvent extracted before the meal was used affects residual oil and hence oxidative stability. Cold pressed linseed oil, standardised on alpha-linolenic acid, is a separate product and is not an extract. Cyanogenic glycoside content is a routine specification point for every linseed-derived material, since the seed carries linustatin and neolinustatin and their breakdown releases hydrogen cyanide.

In the United States linseed and its products have a long history of food use, and whole and milled seed is a conventional food ingredient. The Food and Drug Administration has responded without objection to generally recognised as safe notifications covering flaxseed and certain flaxseed preparations for defined food uses, which is the basis on which the milled seed and the gum are used. Extracts sold into supplements are dietary ingredients under the Dietary Supplement Health and Education Act, manufactured under 21 CFR Part 111, and a purified lignan concentrate without an established marketing history would be assessed as a new dietary ingredient.

In the European Union linseed has an established history of consumption and is a conventional food, while concentrated lignan and purified mucilage preparations that depart substantially from traditional intake can fall within the scope of the novel food Regulation and must be checked against the specification. The European Food Safety Authority has assessed exposure to hydrogen cyanide arising from cyanogenic glycosides in linseed, which is why residual cyanide is tested on every linseed-derived material and why guidance exists on consumption of raw linseed. The European Pharmacopoeia carries a monograph for linseed, which sets the identity and swelling index methods most buyers reference for the whole seed and the mucilage. No health claim for linseed lignans appears on the EU register of authorised claims. Codex has not published a specification for linseed extract.