Simultaneous quantification of rubber, inulin, and resins in Taraxacum kok-saghyz (TK) roots by sequential solvent extraction

Taraxacum kok-saghyz (TK) is being developed as an alternative source of natural rubber (NR). Three valuable constituents of TK roots are NR, inulin and resins. Previous methods required independent measurements to quantify each of these constituents. In addition, the co-extraction of non-target compounds leads to significant errors in the measurement of rubber concentration in roots and processed samples. Accelerated solvent extraction (ASE) is an automated method that allows the rapid extraction of samples with multiple solvents and excellent repeatability. The objective of this study was to develop an optimized multi-solvent ASE method to improve the accuracy of NR, inulin and resin quantification in TK roots. Water, acetone, and hexane were used to extract inulin and saccharides, resins, and rubber, respectively. Root preparation, extraction temperatures and times, sample size (1.0 and 0.25 g), and the number of extractions were evaluated. Two, 40-min water extractions at 95 °C; one, 40-min acetone extraction at 40 °C; and three, 20-min hexane extractions at 160 °C were determined to be optimal based on completeness of extraction and time. Milling roots to less than a 2 mm particle size, and using a sample size of 250 mg improved the recovery of resin and rubber but not of water extractables. This automated multi-solvent method improves the accuracy, repeatability and speed of the quantification of TK rubber, inulin and resins, and thereby the assessment of breeding strategies and processing.