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Title: SUPERCRITICAL FLUID EXTRACTION OF VERNONIA GALAMENSIS SEEDS

Author
item King, Jerry
item MOHAAMED, ALI - VIRGINIA STATE UNIVERSITY
item Taylor, Scott
item MEBRAHTU, T - VIRGINIA STATE UNIVERSITY
item PAUL, CLAUDIA - VIRGINIA STATE UNIVERSITY

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Vernonia is an alternative crop whose extracted oil has potential industrial use due to the presence of a unique functional fatty acid in its composition. For this reason, alternative methods of extracting and processing the oil and meal from the vernonia plant are desirable. In this study, an environmentally-benign method of oil extraction was studied using gcompressed carbon dioxide as the extraction solvent. To affect the carbon dioxide-based extraction method, higher pressures and temperatures must be applied to obtain satisfactory yields of the oil. An additional benefit of using these extraction conditions is reducing the contamination level of undesirable fatty acids in the final oil and meal. This has been partially accomplished using the above extraction method, which negates the effect of the agent in vernonia seed that causes the production of the free fatty acids. In addition, this study demonstrated that by regulation of the extraction gas density, one can produce extracts having variable and desired compositions for industrial use. Such improved processing methods can increase the quality of oil for the end users of this unique plant oil, and thereby provide a potential additional uses for this alternative crop.

Technical Abstract: Vernonia galamensis is an excellent source of a seed oil rich in vernolic acid. However, the seeds of this plant exhibit a high lipase activity in the dormant state. The activity of this enzyme is apparent as vernonia oil will undergo lipolysis when the seeds are crushed prior to extraction. In this study, supercritical fluid extraction (SFE) utilizing carbon dioxide has been examined as an alternative solvent, at different pressures, temperatures and cosolvent concentrations. The use of supercritical fluid carbon dioxide (SC-CO2) as the extraction fluid under high temperatures and pressures has the potential during the extraction to inhibit the lipolysis reaction by reducing the activity of the enzyme, and hence the production of undesired fatty acids. Vernonia seeds were ground with dry ice prior to extraction to minimize any nascent lipase activity. Selective SFE was conducted at various pressures, temperatures, modifier concentrations, and total volume of CO2 used to see if the vernolic acid content of the resultant extract could be enriched. SFE data showed that an increase in pressure and temperature significantly increased the amount of extracted oil as well as the vernolic acid content. A significant reduction in the free fatty acid content of the oil from 69 to 8 mg/g oil was observed with increasing extraction pressure. Exhaustive extraction of the oil could be attained via SFE with neat CO2 and with ethanol-modified CO2, however, regrinding the matrix after the initial extraction, followed by reextraction of the seed matrix, was necessary in these cases. The resultant oil and extracted meal were characterized with respect to free fatty acid content, phospholipids, and percent protein.