Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2014
Publication Date: 6/27/2014
Citation: Fang, X., Moreau, R.A. 2014. Extraction and demulsification of oil from wheat germ, barley germ, and rice bran using an aqueous enzymatic method. Journal of the American Oil Chemists' Society. 91:1261-1268. Interpretive Summary: Wheat germ oil is a specialty oil that is mainly used as a supplement and in cosmetic applications. Its main unique property is its high levels of Vitamin E. Although some wheat germ oil is obtained by mechanical pressing where yields are about 50%, most is obtained by hexane extraction where oil yields are about 99%. Aqueous enzymatic methods have been developed as safer and environmentally-friendly “green” processes to extract edible oil from soybeans, corn germ and other oil rich material. The current study was undertaken to try to develop an aqueous enzymatic oil extraction process to extract wheat germ oil from wheat germ. Two previous papers reported processes to produce emulsified wheat germ oil (the oil was still associated with water), but there is a need for a process that produces free wheat germ oil (a clear oil phase with no emulsion). The current paper reports an aqueous enzymatic oil extraction process that was optimized to achieve a free oil yield of about 64% from commercial wheat germ. Using the process optimized in this paper for wheat germ, about 46% free oil was obtained from barley germ and about 35% free oil was obtained from rice bran.
Technical Abstract: An aqueous enzymatic method was developed to extract oil from wheat germ. The parameters that influence oil yield were investigated, including wheat germ pretreatment, comparison of various industrial enzymes, pH, ratio of wheat germ to water, reaction time and demulsification. Pretreatment at 180ºC in a conventional oven for 4 minutes reduced the moisture to 2.20% and significantly increased the oil yield. A combination of protease (Fermgen) and cellulase (Spezyme CP) added simultaneously, resulted in a 72% yield of emulsified oil from wheat germ (both commercial and laboratory milled wheat germ). Using oil extraction conditions optimized for wheat germ, yields of 51% emulsified oil were obtained from barley germ (laboratory milled), and 39% from rice bran. Three physical demulsification methods (heating, freeze-thawing, and changing pH) and treatment with six enzymes (Protex 6L, Protex 7L, Alcalase, Fermgen, Lysomax and G-zyme 999) were compared. After demulsification with Protex 6L, free oil yields of , 63.81% were obtained from commercial wheat germ, and 59.48% from laboratory milled wheat germ, Using demulsification conditions optimized for wheat germ, yields of 45.71% free oil were obtained from barley germ and 35% from rice bran.