Selection Of A New Type Solvent For Vegetable Oil Extraction

Recently, the current extraction solvent for vegetable oil, n-hexane, for its hazard to human being health and environment, has been incessantly questioned by expert and scholar. So choosing a new extraction solvent, decreasing the loss of solvent, and developing the new extraction process, have been the focuses of oil industrial technology innovation. In this paper, based on the leaching rate, the quanlity of the crude oil and meal, the desolventization of crude oil and meal, the extraction conditions of five solvents (n-pentane, n-heptane, cyclohexane, ethanol and isopropylal alcohol (IPA)), have been studied systematically around the central target that screening a new type solvent for vegetable oil extraction. And, the extraction conditions of n-pentane were optimized. The production of low-temperature meal was attemptted.Using six solvents to extract the soybeen oil, the extraction efficiency was reflected by the residual oil in meal. In a given condition, the residual oil in meal.is: n-pentane(0.87%), n-heaxan (0.98%), n-heptane (1.33%), IPA (1.49%), ethanol (1.95%), cyclohexane (2.55%). The result showed that the extraction efficiency of n-pentane was similar with that of n-hexane. The optimum conditions for the extraction of the soybean flakes using n-pentane were: the flakes thickness 0.231mm, the moisture content 6.63%, the extracting times 3, the extracting temperature 26℃.In these conditions, the residual oil in meal was 0.97%.Through the quanlity analysis of the crude oil, which extracted at different temperature, thickness of flakes, and the moisture of flakes, the acid value and the phosphatide content of different miscellas were: n-hexane (1.87mgKOH/g, 3.54%), cyclohexane (2.39mgKOH/g, 3.04%), n-pentane (3.84mgKOH/g, 4.27%), n-heptane (3.53mgKOH/g, 4.10%), ethanol (2.97mgKOH/g, 3.94%), IPA (3.42mgKOH/g, 4.52%). The quanlity of miscella which extracted with n-pentane was better, and similar to the quanlity of miscella which extracted with cyclohexane. Desolventizing at given temperature and vacuum degree, which was 78.47kPa, the residual solvent in the miscellas were: n-pentane (6.77mg/Kg), n-hexane (11.30mg/Kg), n-heptane (35.02mg/Kg), cyclohexane (38.55mg/Kg), IPA (62.36mg/Kg), ethanol (103.66mg/Kg). N-hexane and n-pentane were easy to desolventize.Desolventizing at given temperatures and vacuum degree of 78.47kPa, the content of residual solvent and NSI in the different meals were: n-pentane (0.33mg/Kg, 69.5%), n-hexane (5.56mg/Kg, 55.56%), n-heptane (36.70mg/Kg, 46.84%), cyclohexane (51.31mg/Kg, 49.55%), IPA (22.36mg/Kg, 43.1%), ethanol (11.66mg/Kg, 41.5%). The NSI quickly decreased when extracted with ethanol and IPA. The NSI of meal defatted with n-pentane was excellent. And the urease activity of the different meals were similar. After desolventizing for 30min at 40℃, the NSI of the meal was 81.4%, and the residual solvent was 142.3mg/Kg. The quantity of the meal was accorded with national standard.Comprehensive surveys about the six solvents showed the miscella extracted with cyclohexane was better, but the solvent was hard to remove. The miscellas extracted with n-heptane and the alcoholic solvents were poorer and hard to desolventize. N-pentane had a good desolventizing performance, a better extraction efficiency, and a low desolventizing temperature. So, n-pentane had a good application prospect, when used for low-temperature meal production,...