| Corn is the second most staple crops in China after the rice. There are abundant resources. In the 20 years, further processing industry of Corn in China has been developing rapidly. And the amount of finish was more than 10 million tons. But there are also a lot of by-products. This study discussed preparative technoique of high purity Linoleic Acid. Which can make full use of the resources, and compare with the Corn germ meal used for feed after the oil was squeezed, the economic value was improved for five times.There is high content of theω-6 unsaturated fatty acids containing linoleic acid mainly and vitamin E in Corn germ oil which is known as health care oil internationally. Theω-6 unsaturated fatty has important physiological function for human body.Which affected the function of cell membrane, gene expression and cardiovascular disease prevention.In this paper, the major factors, which affected the hydrolysis reaction of Corn germ oil, was studied. The technology and influencing factors of esterification were discussed. And the suitable condition was determind. With Fatty Acid Methyl Ester as material, high purity Linoleic Acid was prepared in supercritical CO2 fluid extraction fractionation technique and urea inclusion fractionation. The main research results were as follows:1. Mix the methanol and oil as the ratio of 2:1. The amount of KOH was determined when saponification equivalent of Corn germ oil was 1.1. The hydrolysis reaction was completely in water in 80℃for 100min. And acid value was 207.85 mg KOH/g.2. With 5mL 5% H2SO4-methanol solution as a catalyst, the esterification of 1g fatty acid was reacted completely in water in 70℃for 30min. The conversion rate of fatty acid ester was highest. If taking Corn germ oil as raw materials for reaction, under the same conditions, fatty acid methyl ester conversion rate decreased by 64.73%. So esterification was suitable for fatty acid.3. With 10mL 0.8mol/L of KOH-methanol solution as a catalyst, esterification of 1g Corn germ oil was reacted completely in water in 30℃for 15min. And the conversion rate of fatty acid ester was highest. But it's only 65.24% compared with esterification with H2SO4-methanol as catalyst. If taking fatty acids as raw materials, the conversion rate of fatty acid methyl ester decreased by 91.45% under the same conditions. Therefore, alkaline esterification was suitable for oil.In contrast, the conversion rate of fatty acid methyl ester was higher with H2SO4-methanol as catalyst. So the study carried out with H2SO4-methanol as catalyst. 4. Effection of raw material volume, fractionation temperature, fractionation pressure, CO2 flow rate, extractive temperature and pressure in supercritical CO2 fluid extraction-fractionation technique were studied. The results showed that when the raw material volume was 80g, fractionation temperature was 40-50-60-70℃, fractionation pressure was 12Mpa, CO2 flow rate was 13L/h, extractive temperature was 35℃and extracting temperature increased from 15MPa to 21MPa gradually, content of linoleic acid can reach to 69.70%.5. The linoleic acid was extracted through urea inclusion fractionation. The procedure of urea inclusion fractionation was discussed. The main factors of the urea inclusion reaction was studied through single factor, which determined the optimum experimental condition. When the ratio of alcohol and urea was 4-6 mL/g, the ratio of urea and aliphatic ester was 5-7g/g, inclusion time was 12-16h and the urine inclusion temperature was 7-17℃, the content and recovery rate of linoleic acid was higher.6. Four factors three levels of orthogonal quadratic regression based on the single-factor test was designed. By response surface analysis, the quadratic polynomial model of content and recovery rate of linoleic acid was made sure. Considering the actual operation, the optimization process conditions were as follows:ratio of alcohol and urea (x1) was 5.5 mL/g, ratio of urea and aliphatic ester (x2) was 6.3 g/g, inclusion time (x3) was 14.5h, and the inclusion temperature (x4) was 14℃. After three tests, content and recovery rate of linoleic acid were 97.13±0.83%,45.53±0.65%.
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