Patent ID: 8133518

Claim:
A method for preparing edible plant oil comprised of unsaturated fatty acids devoid of saturated fatty acids, the method comprising: performing a transesterification reaction of the edible plant oil by mixing the edible plant oil with excessive amount of anhydrous C 1 -C 8 alkanol and a catalytic amount of C 1 -C 8 alkoxide of alkali- or alkali-earth metal and stirring the mixture until the oil/alkanol interface is disappeared to prepare alkylester of fatty acids from the edible plant oil, neutralizing the reaction mixture by the addition of equi-molar amount of C 1 -C 4 organic acid or inorganic acid to destroy catalytic activity of the alkoxide after the end of the transesterification reaction, optionally recovering the anhydrous alkanol for recycling by distillation of the neutralized reaction mixture and extracting the remaining residue with an organic solvent to obtain the mixture of alkylesters of saturated and unsaturated fatty acids; heating the obtained mixture of alkylester of saturated and unsaturated fatty acids with a C 1 -C 8 alkanol solution of urea to form a urea-fatty acid-alkylester and then eliminating a crystalline complex of urea-saturated fatty acid-alkylester complex by filtration, and obtaining an alkylester of unsaturated fatty acids by after-treatment on the filtrate; and mixing three molar amount of the obtained alkylester of unsaturated fatty acids with equimolar amount of C 1 -C 8 fatty acid-triglyceride and a catalytic amount of a C 1 -C 8 alkoxide of alkali- or alkali-earth metal to perform an interesterification reaction and treating the reaction mixture to remove the C 1 -C 8 fatty acid-alkylester produced by the interesterification, neutralizing and extracting the reaction mixture with an organic solvent after the end of the interesterification reaction, and then concentrating the reaction mixture to prepare the edible plant oil comprised of unsaturated fatty acids devoid of saturated fatty acids.