Full-press oil extraction of Cuphea (PSR23) seeds

Authors: Evangelista, Roque; Cermak, Steven - Steve

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2007
Publication Date: 11/26/2007
Citation: Evangelista, R.L., Cermak, S.C. 2007. Full-press oil extraction of Cuphea (PSR23) seeds. Journal of the American Oil Chemists' Society. 84:1169-1175.

Interpretive Summary: Cuphea is a new oilseed crop that is currently being developed as a potential domestic source of saturated medium chain fatty acids (MCFAs) used in soaps, detergent, cosmetics, lubricants, and food applications. Half of the MCFAs used by the United States soap and detergent industry is obtained from coconut and palm kernel oils, while the other half is from petroleum. Cuphea PSR23 has been the subject of field studies for the past six years in west central Minnesota and central Illinois to establish the best agronomic management practices in preparation for its commercial production. Recent seed increases had provided sufficient amount of seeds to pursue an oil extraction study, at the same time, produce the much needed oil for product development and testing. This study was conducted to establish the processing conditions for optimum press performance and oil quality when extracting oil using a screw press. The results showed that full pressing can be easily accomplished with minimal seed preparation. The seeds are usually stored at around 10% moisture, hence moisture adjustment is unnecessary. Cooking and drying the flaked seeds down to 4 to 5% moisture was sufficient for good oil recovery with minimal impact in oil quality. Our findings provide the first guidelines on conditions for full-press oil extraction of Cuphea seeds that could be used by industry researchers or partners and commercial crushers who are interested in producing oil and other co-products from Cuphea.

Technical Abstract: Cuphea PSR23, a semi-domesticated, high-capric acid Cuphea hybrid, is being developed as a potential commercial alternative source of medium chain fatty acids. Recent seed increases in Cuphea had provided sufficient amounts of seeds to pursue an oil extraction study and, at the same time, produce much needed oil for product development and testing. This study evaluated the effects of initial seed moisture and final moisture of cooked flaked seed on Cuphea's pressing characteristics and the quality of the re-extracted oil. Seeds with 9 and 12% initial moisture contents (MC) were flaked and cooked at different residence times to produce cooked seeds with MC of 3.0 - 5.5%. Cooked seeds were pressed using a heavy duty laboratory screw press. Eighty and 84% oil were extracted from cooked seeds with 5.5% and 3.0% MC, respectively. The press load for seeds with 9% initial MC exhibited a lower load increase (9.1% per 1% decrease in MC) than the seeds with 12% initial MC (16.4% per 1% decrease in MC). The press rate decreased by 4% as the cooked flaked seed MC decreased. The amount of foots in the oil increased from 3% to 6.6% and chlorophyll content increased from 200 to 260 ppm as cooked flaked seed MC decreased from 5.5% to 3.0%. FFA content remained at the 2.5% level for all cooked seed MC studied. No differences in the amounts of oil extracted, foots, chlorophyll, and free fatty acid contents were observed between seeds with 9% and 12% initial MC. The phosphatide content increased as the cooked flaked seed MC decreased, but the amounts were still within the levels of water-degummed oil.