Enzyme and surfactant-aided oil extraction

The role of enzymes in oil extraction from oilseeds is to hydrolyze the structural components of plant cells and facihtate the release of oil. Hence, enzyme selection depends on the composition of the cell wall and membrane that encapsulates oil bodies and the cytoplasmic network where oil bodies are imbedded in the oilseed. Carbohydrases such as cellulase, hemicellulase and pectinase and protease are effective in breaking up the cell 

Smaller particle size of feed material is an indication of efficient grinding, which mechanically breaks apart the cell stmcture of materials (Rosenthal et al., 1996). In addition, smaller particle size results in larger surface area, which allows better contact between oilbearing material and solvent and reduces resistance to the diffusion of oil, as well as other components, from the solid matrix to the aqueous medium. The rate of enzyme diffusion into the solid substrate is also improved with smaller particle size. Although the importance of smaller particle size has been well recognized, only a few studies have been carried out to investigate its effect on oil extraction yield. A study on enzymatic soybean oil extraction showed that the oil extraction yield increased with decreasing particle size from 12(K)(un to less than 200 pm (Rosenthal et al., 2001). 

The concentration of enzyme in the extraction medium greatly affects the enzymatic reaction rate and the oil extraction yield. It has been demonstrated that an increase in enzyme concentration from 0.2 to 2.5% (v/w) resulted in significant improvement in oil recovery, but further increase to 5% did not bring additional enhancement in rapeseed oil extraction yield (Zhang et al., 2(X)7). The amount of enzyme needed to achieve acceptable oil yields needs to be determined to optimize yield and the cost of enzyme for economic feasibility. Action of enzyme on oilseeds and mass transfer between the aqueous medium and the seed material are time dependent processes. In most cases an increase in extraction time results in an improvement in the oil extraction yield, but the improvement slows down and eventually stops as time prolongs (Sharma et al., 2002). Hence, extraction time is a variable 

---