MICROWAVE AND ULTRASOUND ASSISTED EXTRACTION OF SOYBEAN OIL

摘要

The effect of ultrasound and microwave assistance in enhancing extraction oil yields from soybeans when different solvents are used for extraction was investigated in two separate experiments. Each study involved a three-factor factorial following a completely randomized design that was replicated three times. Treatment factors investigated in the microwave processing study were microwave pretreatment time (0, 0.5, 1, and 2 min), solvent (isopropanol, hexane, and 3:2 hexane-iso-propanol mixture), and extraction time (0.5, 1, 1.5, 2, and 3 h). Ultrasonic intensity (0, 16.4, 20.9, and 47.6 W/cm{sup}2) was substituted as a treatment factor in the sonication study. Solvent extraction was accomplished by immersion of ground soybeans in a given volume of solvent at ambient temperature. While oil yields did not approach the 19.2% analyzed oil content of the TN 96-58 used as the test material, they were found to increase with both intensity of the process assistance and extraction time under the conditions of the studies, particularly with hexane and the mixed solvent. The highest yield result of 12.21 gfrom 100 g soybeans was obtained with the mixed solvent under 47.6 W/cm{sup}2 sonication. The results obtained with the mixed solvent with both microwave pretreatment and ultrasound assistance are difficult to explain in terms of physical chemistry. The results with isopropanol indicate that the efficiency of the extraction process depends greatly on the molecular affinity between solvent and solute and that process assistance tested in this study cannot overcome inherent deficiencies in solvent-solute interactions.