Study On The Chinese Pricklyash Seed Oil And The Purification Of α-Linolenic Acid From It

The component of Chinese pricklyash seed, the separation of Chinese pricklyash seed oil and its physical and chemical characters are studied in this paper. And I used Chinese pricklyash seed oil as material. After knowing its major physical and chemical characters and its fatty acid compositions, I got reseach in the separation and purification ofα—linolenic acid in it. The reseach results are showed as follows:(1) The main components of Chinese pricklyash seed and Chinese pricklyash seed without crust were analysied at first. The content of the main components are different between them. In the Chinese pricklyash seed, the moisture content is 16.8%, crude fat 5.3%, crude protein 5.5%, ash 7.3% and crude fiber is 61.3%. But after peeling the crust of it, the moisture content is 8.3%, crude fat 41.2%, crude protein 30.7%, ash and crude fiber are 4.0% and 13.5%.As the Chinese pricklyash peel, the Chinese pricklyash seed peel also contain volatile components, which makes seeds with the aroma. There are more than 30 kinds of volatile components in it. And P-linalool is the highest concentration which contains up to 60.4%. It plays a major role in aroma components of Chinese pricklyash seed.(2) I respectively used the methods of Soxhlet extraction and solvent extraction to separate and extract the Chinese pricklyash seed oil.Soxhlet extraction: in order to extract better, the petroleum ether is for good, and extraction time for 7 hours is appropriate, then the extraction rate can reach to 92.76%.Solvent extraction:to ues petroleum ether and ether extraction were both good, but taking into account the cost of ethyl ether and petroleum ether factors, extraction should be based on petroleum ether as solvent. And soak 3～5 hours for the best, then the extraction rate can be up to 73.31%.(3) The physical and chemical properties of Chinese pricklyash seed oil and its fatty acid composition:As Chinese pricklyash seed oil is rich in polyunsaturated fatty acids, when compared with other vegetable oils, it has high iodine and its acid value and peroxide value are also high.The buying Chinese pricklyash seed oil is obtained after special treatment and squeeze. It is in liquid state at room temperature and not under the turbid at the-10℃-storage. It shows light yellow color, clean and transparent. The oil extracted from the whole Chinese pricklyash seed has a lot of impurities and wax content which make the oil show brown color. And it is not clear but a little black. But the oil from Chinese pricklyash seed without crust has little impurities and it looks clear.The fatty acid compositions of Chinese pricklyash seed oil were six types of fatty acids mainly. They are Palmitic acid 1.54%, Palmitoleic acid 10.54%, Stearic acid 1.46%, Oleic acid 25.36%, Linoleic acid 26.84% and a-Linolenic acid 34.48%.(4) The preparation of free fatty acid (FFA)The optimal conditions of the hydrolysis of Chinese pricklyash seed oil during saponification were showed as follows: the hydrolysis temperature was 80℃and the time was 60min for the best. The most appropriate concentration of NaOH with ethanol was 4%. And the ratio of Chinese pricklyash seed oil and the solution of NaOH with ethanol was 1:3. Under this condition, the acid value of free fatty acids which obtained after hydrolyzing was 176.74 mgKOH/g.(5) The purification of a-linolenic acid from Chinese pricklyash seed oilThe methods of freezing acetone and molecular distillation were both used.The free fatty acid of Chinese pricklyash seed oil (FFA) was soluted in acetone at the ratio of 6:1 (acetone/FFA), kept at-30℃in the low-temperature refrigerator for 5 hours. And the solvent purity of acetone was 4%. Separated crystallization from solution by filtration, recycled the fatty acid in the filtrate at last and attained the low-temperature crystallization sample. With the gas chromatography analysis, the content of ALA in the sample reached to 61.5% from 33.3%.The technology of enriching ALA from Chinese pricklyash seed oil by molecular distillation has been studied. The influence of distillation pressure, distillation temperature, feed rate and agitating speed on the purity of ALA were analyzed by the orthogonal test. The optimum operating conditions were determined, which is distillation pressure of 0.2—0.3Pa or 5.0—8.0Pa, distillation temperature of 120℃, feed rate of 30d/min and agitating speed of 200 r/min. Under this condition, the purity of a-linolenic acid in Chinese pricklyash seed oil increased from 33.3% to 63.9%.