Compositional Analysis of Taraxacum kok-saghyz Roots, an Alternative Source of Natural Rubber

Natural rubber (NR) is a critical raw material nearly all of which is produced in Asia from a single plant species. This lack of biological and geographical diversity, coupled with burgeoning demand, makes it imperative that alternative sources are developed. Ohio, the center of the US rubber industry, has addressed this need through the creation of an academic/industry consortium called PENRA led by OARDC. The goal of PENRA is to develop a rubber-producing dandelion, Taraxacum kok-saghyz (TK), as a commercial viable alternative source of high molecular weight NR. In order to improve the value of this crop and make it competitive with other sources of natural rubber, crop production, processing, purification methods and development of potential TKS co-products is needed. The objective of this study was to generate a compositional analysis of field grown TK roots to better characterize potential co-products and identify impurities remaining in TK NR after the current pilot scale purification process. Results showed that 4.4% of the root weight consisted of hexane extractable high molecular weight rubber (Mw > 1,000,000 g/mol, polydispersity of 4.3) and that 2% was acetone extractable (mainly fatty acids and resins). Approximately 60% of the root dry weight was water extractable. Soluble sugars were the most abundant water soluble fraction (32% w/w dry root). Among these, Inulin (a valuable food thickener and sweetener) was the most abundant (17.5% w/w dry root). Substantial amounts of sucrose (9.8% w/w dry root) and pectin (3.5%) were also present. Insoluble components included cellulose (glucan), hemicellulose (xylan, mannan, arabinan, galactan), acetate, lignin and proteins. Total mass closure was greater than 95%. Impurities in the rubber consisted primarily of acid insoluble organic matter (lignin). This study proved the potential of TK roots as a source of not only NR but also of products of importance such as inulin, cellulose, hemicellulose, proteins and lignin.