Separation And Purification Of Unsaturated Fatty Acids

Unsaturated fatty acids such as linoleic acid and palmitoleic acid have positive effects in preventing cancer,treating cardiovascular diseases,and delaying aging,which have been widely recognized in the fields of nutrition and health care.In order to obtain high content of linoleic acid and palmitoleic acid,the linoleic acid in safflower seed oil and palmitoleic acid in seabuckthorn fruit oil were separated and purified by different purification processes.The specific research contents are as follows:First,safflower seed oil with a linoleic acid content of about 75%was used as a raw material.The saponification reaction was carried out by using NaOH,and the acidification treatment of H₂SO₄ was carried out.Further,the influence of the amount of alkali,the amount of alcohol,the reaction temperature,the reaction time and the amount of acid in the reaction process were investigated.As a result,the optimal reaction conditions for saponification were:oil:concentration 5%ethanol aqueous solution?w/w?=1:3,NaOH equivalent was 1.1 saponification equivalent,reaction temperature was 80?,reaction time was 3 h.At this time,that saponification reaction was basically completed;the optimal reaction conditions for acidification were:H₂SO₄ was added in an amount of 1.1 times the amount of NaOH added,the acidification temperature was 80?and the acid value remained basically unchanged at 192.50 mgKOH/g.constant.After saponification and acidification of safflower seed oil,the yield of fatty acids was 85.41%.Then,the mixed fatty acids obtained by saponification and acidification of safflower seed oil were used as raw materials and separated by freeze crystallization.The effects of solvent types?methanol,ethanol,acetone?,oil solubility ratio,freezing time and freezing temperature on linoleic acid content and yield were investigated.The results showed that the mixed fatty acid:ethanol?w/w?=1:1,freezing temperature was-20°C and freezing time was 4 h,the obtained linoleic acid content was 78.81%,the yield was 91.34%.Finally,the mixed fatty acids were separated by urea encapsulation.The effects of urea dosage,solvent type?methanol,ethanol?,ethanol dosage,heating time,inclusion temperature,inclusion time and number of inclusions on the iodine value and yield of the product were investigated.The results showed that the amount of urea was the main factor affecting the purity of linoleic acid and the yield of fatty acids.The optimal process conditions for optimization were as follows:the amount of urea was 1.5 to 2 times the mass of the mixed fatty acid,the amount of solvent was 4 times that of urea,the inclusion temperature was-5°C,the inclusion time was 8 h,and the inclusion was 3 times.Under this conditions,the content of linoleic acid could be increased from 76.98%to 92.30%.Separation and purification of palm oleic acid with sea buckthorn fruit oil.The acid value of seabuckthorn fruit oil was reduced by methyl esterification,and then mixed fatty acid methyl ester was prepared by transesterification.The amount of KOH accounts for 1%of the mass fraction of oil,the amount of methanol is 30%of the mass fraction of oil,the reaction temperature is 60°C,and the reaction time is 1 h.The yield of mixed fatty acid methyl ester is 87.10%.Thereafter,under vacuum conditions of a reflux ratio of 15 and an overhead operating pressure of 40 Pa,C₁₆fatty acid methyl ester product can be obtained by vacuum distillation with the content of 98%.Among them,the content of methyl palmitate in the fatty acid methyl ester was 44.64%,and the content of methyl palmitate was 53.43%.The C₁₆ methyl ester was subjected to pressure filtration,and the effects of solvent dosage,freezing temperature,pressure and pressurization time on the purity of methyl palmitate were investigated.The optimal pressure filtration parameters were obtained:C₁₆ methyl ester:ethanol?w/w?=1:2,the crystallization temperature was 5°C,the pressure filtration pressure was 7 MPa,and the pressing time was 60 s.After three pressure filtration operations,the content of methyl palmitate is high as 92.18%.In summary,the mixed fatty acids prepared from safflower seed oil were separated and purified by freeze crystallization and urea encapsulation,and the content of linoleic acid could reach 78.81%and 92.30%respectively;the mixed fatty acid methyl ester prepared from seabuckthorn fruit oil was separated and purified by vacuum distillation and pressure filtration,and the content of palmitoleic acid could reach 92.18%.