Author: Toshiba
Last saved by: Saritas, Sevim (Euro Fed Lipid)
Company: CIRAD

SC-CO_2 Extraction of Lipids and Terpenics from Guayule Biomass (Parthenium argentatum) 
Teerasak Punvichai^1,2, Ali Amor^1,3, Eric Tardan^1, Serge Palu^1 and Daniel Pioch^1.
^1 UR BioWooEB - Biorefinery Team, CIRAD, 34398 Montpellier France.
^2 Prince of Songlka University, Faculty of Sciences and Industrial Technology, Thailand. 
^3 CTTM, Centre de Transfert de Technologie, 72000 Le Mans, France.
  daniel.pioch@cirad.fr 

Guayule (Parthenium argentatum), a perennial crop under semi-arid climate, synthesizes polyisoprene (Guayule rubber, GR) and resins. Hevea rubber is facing increasing price and possible shortage; GR, similar to Hevea’s, is the most probable alternative source of natural rubber. To date efforts aimed at marketing GR, while the bagasse (90%-dw, dry weight) left after water-based extraction remains underused. Recently, Guayule was successfully grown in France and in Spain (EU-Pearls project), for producing tires and allergy-free gloves. Production cost has shown that in addition to GR, the extraction of other compounds (resins) is required for reaching economic sustainability. Thus Cirad is investigating a “green” process for extracting valuable compounds including lipids. Here reported preliminary results deal with investigating the influence of operating parameters for selectively extracting lipid and terpenic classes: 
- Acetone-based extraction under pressurized conditions above boiling point (ASE-acetone, reference method)
- Under SC-CO_2, investigating parameters acting on extraction efficiency (yield, selectivity). 
	Under SC-CO2, resins extract is higher with ethanol as co-solvent (9.6%-dw; based on dry weight of initial biomass) compared to acetone (6.3%-dw) and to reference protocol ASE-acetone (5,2%-dw). The optimum temperature with SC-CO_2-ethanol is 60°C. Saponification, used for separating resins components, gives constant yield between 2 and 8h, with no effect on the composition of the saponifiable fraction: aromatic carboxylic acids (cinnamic, p-anisic) initially linked to sesquiterpenes are the major components, especially with SC-CO_2-ethanol (68.7%) compared to SC-CO_2-acetone (51.1%) which shows a lower selectivity. The minor components are lipids rich in C18:2, C16:0, C18:3, in between cotton and soybean oils, although poorer in C18:1. In these extracts the unsaponifiable fraction contains sesquiterpenes, with low dependency on extraction temperature with SC-CO_2-ethanol: guayulines, argentatines, known to be bio-actives (anti-insect properties). 
	From these trials SC-CO_2-ethanol shows a higher efficiency compared to SC-CO_2-acetone, and to ASE-acetone. In addition to terpenics, SC-CO_2-ethanol extract yields fatty acids, aromatic carboxylic acids and dibasic acids as potential industrial feed stocks. These carboxylic acids are being further investigated, with SC-CO_2-ethanol as an environmental friendly option for sequential extraction of resins components from bagasse.