Determination of Cyanogenic Glycosides in Flaxseed by Barbituric Acid−Pyridine, Pyridine−Pyrazolone, and High-Performance Liquid Chromatography Methods

A crude enzyme extracted from flaxseed by acetone precipitation was used for the hydrolysis of cyanogenic glycosides to determine total cyanide in flaxseed and flaxseed-derived products. The hydrolysis of cyanogenic glycosides (linamarin, linustatin, and neolinustatin) as well as the endogenous substrate was dependent on the crude enzyme concentration and followed a first-order relationship. Two colorimetric methods using the crude enzyme extract and an established high-performance liquid chromatographic (HPLC) method were compared using 28 flaxseed samples. Total HCN values obtained by all three methods were not statistically different, although those obtained by the HPLC method were higher than those from the colorimetric methods. Keywords: Flaxseed; cyanogenic glycosides; method comparison; crude enzyme extract; Linum usitatissimum; barbituric acid−pyridine; HPLC