Chemical composition of components comprising bast tissue in flax

Components from the bast region of flax (Linum usitatissium) were removed b y hand from seed flax and fiber flax and analyzed by gas chromatography and mass spectrometry. Stems soaked in water were separated by hand into an ou ter layer, which consisted of epidermis with cuticle and parenchyma cells, and fiber bundles. Each of the two fractions were evaluated for chemical ma rkers that could be used to predict the degree of retting and possibly fibe r quality. The outer layer was subsequently treated with a mixed enzyme pre paration to remove the carbohydrate portion, thus providing another fractio n consisting primarily of cuticle. Four main constituent groups were invest igated: dihydroxy fatty acids, long-chain fatty acids and alcohols, sterols , and aromatics. Long-chain fatty acids and alcohols located in the outer l ayer accounted for 80-92% of the total found in both fractions. Aromatics a nd sterols in the outer layer accounted for 29-72 and 27-67%, respectively, of the total and do not appear to be a reliable marker for the degree of r etting. The best markers for retting were the dihydroxy fatty acids, of whi ch 98-99% were accounted for in the outer layer. The main dihydroxy fatty a cids were a mixture of 8,16- and 9,16-dihydroxyhexadecanoic acids and repre sented 87-89% of the total dihydroxy fatty acids measured. As a constituent of cuticle, this compound may serve as an excellent marker for indicating the degree of retting as well as a possible marker for fiber quality becaus e this compound is almost always exclusively associated with the outer laye r and not the fiber.