Studies On The Purification And Modification Of α-linolenic Acid

α-linolenic acid is a kind ofω-3 polyunsaturated fatty acids with 3 double bonds, indispensable to human being, effectively lowering plasma fat and cholesterol concentration, accelerating the fat metabolization and the liver cell regeneration. The technology concentrating a-linolenic acid from faxseed oil was studied systematically, and a mathematical model concentrating a-linolenic acid using urea complextion was set up. The antioxidative of natural antioxidants, including the natural vitamin E, ellagic acid, tea polyphenols, bamboo-leaves flavonids, effecting onα-ethyl linolenate were studied to reduce its oxidention and prolong the shelf time. In order to expand the useness of a-linolenic acid and exert its efficacy, the modification of a-linolenic acid was studied, and the ester derived from phytosterol was synthesized by using microwave method.1 the purification of a-linolenic acidA universal rotable design and SAS analyse were used to optimize of process parameters. The importance sequence of parameters was that: the quality ratio of urea to fatty acid＞complextion temperature＞complextion time; The optimization parameters were as follows: the quality ratio of urea to fatty acid 4.4, complextion temperature-11.1℃, complextion time 14.9h. Then the purity degree of a-linolenic acid was 79.4%; a regressing model was established by SAS analysis: y=34.76+14.18×x₁-0.72×x₂+1.28×x₃-1.50×x²-0.02×x²-0.04×x₃², x₁=the ratio of urea to fatty acids, X₂=complextion temperature, and X₃=complextion time.2 the antioxiannt of a-linolenic acidThe antioxidative of natural antioxidants, such as vitamin E, ellagic acid, tea polyphenols, bamboo-leaves flavonids, effecting onα-ethyl linolenate was evaluated by schaal-oven method and Rancimat inductive time accelerating oxidation process in this paper. The results showed that antioxidantive effects of natural antioxidants on a-ethyl linolenate were as follows: 90% tea polyphenols＞82% ellagic acid＞50% tea polyphenols＞bamboo-leaves flavonids. and a-ethyl linolenate could be stable by adding 0.05% natural antioxidants. Compared with schaal-oven method, accelerating oxidation process is faster, more convenient and easier.3 the modification of a-linolenic acidA microwave method was used to modify a-linolenic acid, and factors synthesizing phytosterol esters of a-linolenic acid were studied, such as mol ratio, catalyzer quantity, microwave power, and reaction time. Thin layer chromatography, UV spectrum, and IR spectrum were used to determine the nature the phytosterol and phytosterol ester ofα-linolenic acid. And the GC method was used to determine the yield of esterification. Through orthogonal experiments, the optical synthetic conditions were as follows: a-linolenic acid to phytosterol mol ratio was 3.5:1, miacrowave power was 660w, heating time was 30min (heating 8times, 4min/time), the quantity of catalyzer added was 0.75%. and the yield of ester was 60.8%. The purity of product was about 90.2% through recrystallization method.