It was attempted to prepare
cis-9,
trans-11 conjugated linoleic acid (
c9,
t11-CLA) and
t10,
c12-CLA concentrates that can be used as foods. A free fatty acid mixture (FFA-CLA) containing almost equal amounts of
c9,
t11- and
t10,
c12-CLAs was esterified with glycerol using immobilized
Rhizomucor miehei lipase, and the resulting acylglycerols (Gly-CLA) were purified by molecular distillation. Contents of
c9,
t11- and
t10,
c12-CLAs in Gly-CLA were the same as those in FFA-CLA:
c9,
t11-CLA, 33.7 wt%;
t10,
c12-CLA, 34.5 wt%. Gly-CLA was first hydrolyzed with an equal weight of water and 1.0 U/g-mixture of
Candida rugosa lipase, and
c9,
t11-CLA-rich FFAs were prepared by molecular distillation: purity of
c9,
t11-CLA based on the total content of
c9,
t11- and
t10,
c12-CLAs, 72.9%. Meanwhile, purity of
t10,
c12-CLA in acylglycerols was 65.0%. To further increase the purity, the acylglycerols were hydrolyzed again with 15 U/g-mixture of
C. rugosa lipase, resulting in enrichment of
t10,
c12-CLA in acylglycerols (purity of
t10,
c12-CLA, 80.4%). Non-selective hydrolysis of
t10,
c12-CLA-rich acylglycerols with 200 U/g-mixture of
C. rugosa lipase produced
t10,
c12-CLA-rich FFAs (purity of
t10,
c12-CLA, 81.5%). In addition,
c9,
t11-CLA-rich FFAs were successfully esterified with glycerol using immobilized R. miehei lipase, and
c9,
t11-CLA-rich acylglycerols can be synthesized (purity of
c9,
t11-CLA, 73.0%). The process was composed of reactions with
C. rugosa and
R. miehei lipases, which can be used for production of foods, and molecular distillation. Hence, the
c9,
t11- and
t10,
c12-CLA concentrates can be used as foods.
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