8.3.3 Production of a structured lipid containing DHA and CA
Tuna oil was acidolyzed with CA to produce a MLM-type structured lipid containing
DHA (Shimada et al., 1996a). Several factors affecting the acidolysis were inves-
tigated, and the reaction conditions determined as follows: a reaction mixture of tuna
oil/CA (1 : 2, w/w) and 4 % immobilizedRhizopuslipase was incubated at 30 8 C with
shaking. Figure 4 shows a typical time course of the reaction. The contents of pal-
mitic and oleic acids in triglycerides rapidly decreased, and attained a constant value
after 20 h. The EPA content gradually decreased and reached a constant value after
40 h. The DHA content scarcely changed during the reaction. The change of the fatty
acid contents in glycerides showed that the reaction proceeded according to the fatty
acid specificity ofRhizopuslipase. Furthermore, the decrease in these fatty acid
contents corresponded to the increase in the CA content, showing that the fatty acids
in tuna oil were exchanged for CA.
Rhizopuslipase acted on DHA only very weakly in acidolysis of tuna oil, acted on
it weakly in esterification of FFAs originating from tuna oil with long-chain fatty
136 8 Production of Functional Lipids Containing Polyunsaturated Fatty Acids with Lipase
Table 3.Activation of immobilizedRhizopuslipase on acidolysis of tuna oil with caprylic acid (CA).
Incorporation Glyceride composition (wt%)
Reaction of CA
cycle (mol %) Triglyceride Diglyceride Monoglyceride
First 31.1 82 15 3
Second 35.8 96 3 1
Third 36.8 99 1 n.d.
Fourth 35.9 99 1 n.d.
n.d., not determined.
Figure 4. Time course of acidolysis of tuna oil with CA using immobilizedRhizopus delemarlipase.
, CA;, palmitic acid;&, oleic acid;&,EPA;^, DHA.