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Large‐scale purification of γ‐linolenic acid by selective esterification using Rhizopus delemar lipase
Author(s) -
Shimada Yuji,
Sakai Norihito,
Sugihara Akio,
Fujita Hiroyuki,
Honda Yo,
Tominaga Yoshio
Publication year - 1998
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-998-0091-y
Subject(s) - chemistry , lipase , chromatography , hydrolysis , fractionation , triacylglycerol lipase , fraction (chemistry) , distillation , vacuum distillation , organic chemistry , sunflower oil , fatty acid , extraction (chemistry) , enzyme , biochemistry
γ‐Linolenic acid (GLA) is a physiologically valuable fatty acid, and is desired as a medicine, but a useful method available for industrial purification has not been established. Thus, large‐scale purification was attempted by a combination of enzymatic reactions and distillation. An oil containing 45% GLA (GLA45 oil) produced by selective hydrolysis of borage oil was used as a starting material. GLA45 oil was hydrolyzed at 35°C in a mixture containing 33% water and 250 U/g‐reaction mixture of Pseudomonas sp. lipase; 91.5% hydrolysis was attained after 24 h. Film distillation of the dehydrated reaction mixture separated free fatty acids (FFA; acid value 199) with a recovery of 94.5%. The FFA were selectively esterified at 30°C for 16 h with two molar equivalents of lauryl alcohol and 50 U/g of Rhizopus delemar lipase in a mixture containing 20% water. The esterification extent was 52%, and the GLA content in the FFA fraction was raised to 89.5%. FFA and lauryl esters were not separated by film distillation, but the FFA‐rich fraction contaminated with 18% lauryl esters was recovered by simple distillation. To further increase the GLA content, the FFA‐rich fraction was selectively esterified again under similar conditions. As a result, the GLA content in the FFA fraction was raised to 97.3% at 15.2% esterification. After simple distillation of the reaction mixture, lauryl esters contaminating the FFA‐rich fraction were completely eliminated by urea adduct fractionation. When 10 kg of GLA45 oil was used as a starting material, 2.07 kg of FFA with 98.6% GLA was obtained with a recovery of 49.4% of the initial content.