Alkaline pretreatment of Taraxacum kok-saghyz (TK) roots for the extraction of natural rubber (NR)

Natural rubber (NR) is an essential biomaterial the supply of which is insecure. Taraxacum kok-saghyz (TK), a rubber-producing dandelion, is an alternative source of NR that has excellent potential for commercial development. Scalable methods for rubber extraction at high yield, quality and purity are needed to meet this potential. We previously developed an aqueous, enzymatic method for the extraction and purification of NR from TK roots. Alkaline pretreatment significantly improved the yield of TK NR using this method, but its effects on NR yield, purity and quality at a range of base concentrations and temperatures was not tested. In this study, TK roots (after inulin extraction) were pretreated at sodium hydroxide loading rates of 0, 33, 66 and 132 mg NaOH/g and temperatures of 25, 70, 125 and 160 degrees C. Treatment with pectinase and cellulase enzymes was used to solubilize root structural carbohydrates and liberate NR. Rubber quality and impurities were then characterized. Results showed that increasing NaOH loading rate and temperature significantly improved rubber yield, but reduced rubber molecular weight and rubber gel content. Rubber purity and thermal properties were largely unaffected by pretreatment conditions. FTIR and SEM analysis revealed that alkaline pretreatment primarily altered protein and other secondary components of TK NR.