An effective method to reduce the wax content in sunflower-seed oil

CRAPISTE, GUILLERMO; BAÜMLER, ERICA; CARELLI, AMALIA

Madrid

Congreso; Euro Fed Lipid Congress. Fats, Oils and Lipids for a Healthier Future; 2006

Euro Fed Lipid

Waxes are natural components of sunflower seeds, mainly long-chain fatty esters, that pass to the oil in the extraction process, and they are partially removed during oil refining. The objective of this study was to investigate the effect of washing the sunflower seed with a solvent on both the extracted-oil wax content and the  seeddehulling ability. Wax distribution in sunflower seeds as well as wax  composition in sunflower oils obtained from washed seeds and in solvent extracts were determined by capillary-gas chromatography. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and wax distribution was observed by scanning-electron microscopy. Most of the crystallized waxes (> C44) were superficially located in the seed hull, being its contribution to the wax content in the oil around 80 %, when only this fraction was considered. The seeds were superficially washed with hexane and ethanol under different temperatures (20-40 ºC) and contact times (20-40 s), being hexane the most effective. The washing procedure preferentially removed the C44-C48 wax fraction, while the loss of seed oil was practically negligible. The use of hexane at 40ºC during 20s extracted approximately 37% of the total-wax content, reaching values of 80% with respect to the C44-C48 fraction. The removal material consisted mainly of crystallized waxes with the following typical composition: C40: 0.7%, C41: 0.1%, C42: 7.8%, C43: 0.7%, C44: 28.8%, C45: 1.8%, C46: 29.9%, C47: 1.1%, C48: 14.3%, C49: 0.6%, C50:7.2%, C51: 0.5%, C52: 4.4%, C53: 0.3%, and C54:1.9%. In addition, the seed washing positively affected the dehulling ability. In conclusion, a previous seed washing with hexane at environment temperatures during short times could diminish the wax oil content and improve the seed dehulling efficiency, reducing the processing losses and the refining costs. Moreover, this methodology would allow the recuperation of sunflower waxes as a by-product for commercial use.