Extractable latex yield from Taraxacum kok-saghyz roots is enhanced by increasing rubber particle buoyancy

Abstract

Taraxacum kok-saghyz (TK) is a leading alternative rubber-producing plant that produces natural rubber (NR) latex in laticifers within its roots. Unlike the tropical rubber tree, Hevea brasiliensis, TK can be grown in temperate regions, such as the northern United States, as the basis of a domestic rubber production industry. To support such an industry, efficient, scalable rubber extraction techniques are needed. In this study, aqueous extraction was used to recover TK natural rubber latex (TNRL) from four harvests of greenhouse-produced TK roots with a new technique that improves rubber particle buoyancy in root homogenate by chelation. The new method includes harvest, cleaning, and homogenization of freshly harvested roots, followed by centrifugation, vacuum collection of latex, and purification. Treatment of homogenate with ethylenediaminetetraacetic acid (EDTA), a divalent cation chelator, allowed more than twice as much latex to be extracted from fresh homogenate. EDTA-treated rubber particles contained lower concentrations of divalent cations than untreated ones in fresh homogenate and homogenate stored for two weeks. Long term (three months) storage of root homogenate similarly yielded more latex than fresh homogenate and had low divalent cation rubber particle concentrations, indicating that heavy cations had slowly leached from the particles into the aqueous medium during storage. Rubber particle size was larger in this treatment suggestive of rubber particle agglomeration but this was prevented and reversed by EDTA. Removal of divalent cations via chelation increased particle packing density of particles in concentrated latex and appeared to increase the gel content of dried latex samples. Molecular characterization of dried samples of purified TNRL established that the rubber was of the high molecular weight needed for product manufacturing.