Chelating Agents and Enzyme Retting of Flax

Abstract

Chelators added to pectinase-rich enzyme mixtures increase the efficiency of enzyme retting of flax. The multitude of available chelators requires research to optimize enzyme retting for cost and fiber quality, Of several chelators tested, ethylenediaminetetraacetic acid (EDTA) is the most effective in sequestering calcium from solution, with substantial activity even at pH 4 or 5. Phosphate is also effective, but only at high pH. EDTA and Mayoquest 200, a commercial product with ∼37% EDTA, in combination with Viscozyme L or Lyvelin, commercial enzymes with polygalacturonase activities, yield high Fried test scores, indicating efficient separation of fibers from core tissues. Neither chelator nor enzyme at the levels tested alone effectively rets flax at a pH of around 5. In contrast, EDTA at 20 mmol/L levels and alkaline pH yields high Fried test scores. The addition of BioPrep, a commercial pectate lyase, does not influence retting measured by the Fried test with EDTA at alkaline pH, but the enzyme does improve retting with the weaker chelator sodium tripolyphosphate. The quality of fibers, as determined by the yield of fine fibers obtained by passing retted flax through the Shirley analyzer, is substantially greater with EDTA plus Viscozyme at pH 5 than alkaline chemical retting with EDTA, sodium tri polyphosphate, or sodium oxalate without enzyme. EDTA is the most effective chelator at acidic pH levels for stimulating flax retting by various commercial pectinase-rich enzyme mixtures. However, other less expensive candidates require additional study for more cost-effective formulations and applicable fiber properties.