INFLUENCE OF CHELATING-AGENTS AND MECHANICAL PRETREATMENT ON ENZYMATIC RETTING OF FLAX

Adding chelating agents, i.e., oxalic acid and ethylenediamine-tetra-a cetic acid (EDTA), substantially increases the retting effect on flax by the commercial enzyme products Ultrazym and Flaxzyme (Novo Nordisk) , as shown by scanning electron microscopy, release of reducing sugars , and the Fried test. Degradation of pectin-rich citrus peel by these enzymes also increases with the addition of oxalic acid and EDTA, whil e citric acid has a low or insignificant effect. Oxalic acid at 50 mmo l concentration reduces the amount of Flaxzyme required to effectively ret flax stems, according to the Fried test, by a factor of about 50. Retting with Flaxzyme and 50 mmol oxalic acid is completed in approxi mately half the time at 45 degrees C, compared with that at 22 degrees C. A mechanical pretreatment that crushes flax stems by pulling them over a surface at a 90 degrees angle opens the flax structure and furt her increases the efficiency of enzymatic retting. These procedures ap pear to modify both the chemical and structural features of flax, and they reduce the time as well as the amount of enzyme required to ret f lax, therefore improving technical efficiency and economic attractiven ess at the commercial level.