Front Matter

mmHg gave 0.5 kg of distillate (acid value, 176) and 1.5 kg of residue (acid value, 4;

GLA content, 56 wt%). The first and second distillations recovered 89 % and 94 %

of glycerides, respectively. This result showed that the film distillation was very

effective for removal of FFA in the large-scale production of PUFA-rich oil.

8.2.5 Reaction kinetics of selective hydrolysis

The glycerides obtained by selective hydrolyses of PUFA-containing oils contained

more than 80 wt% of triglycerides, in spite of over 50 % hydrolysis. To clarify this

phenomenon, we investigated the reactions occurring concomitantly with hydroly-

sis. The results showed that PUFAs were esterified not with glycerol but PUFA par-

tial glycerides even in a mixture containing 50 % water, and that interesterification

between partial glycerides also occurred. In addition, hydrolysis activities on PUFA

glycerides were in the order of mono-PUFA>di-PUFA>tri-PUFA, and hydrolyses

of PUFA partial glycerides generated tri-PUFA. On the basis of these results, we

concluded that selective hydrolysis proceeded as follows: (i) The ester bonds of

fatty acids other than PUFA were hydrolyzed in the early stage of reaction, and

PUFA-containing partial glycerides were generated. (ii) Parallel to the hydrolysis

of the resulting partial glycerides, esterification occurred between partial glycerides

and FFAs including PUFAs, and interesterification also occurred between partial

glycerides. (iii) The hydrolysis of esters of non-PUFAs was faster than those of

8.2 Production of PUFA-rich oils by selective hydrolysis 133

Table 2.Large-scale purification of GLA-rich oil from reaction mixture obtained by selective hydrolysis
of borage oil withCandidalipase.

Amount of GLA GLA

Procedure Weight Acid value glycerides^1 Content^2 Recovery^2
(kg) (kg) (wt%) (%)

Original oil 7.00 n.d. 7.00 22.2 100

Hydrolysis (1) 6.29 122 2.45 45.7 71.8

Film distillation

Distillate 1–1 3.26 197 0.05 n.t. –

Distillate 1–2 0.67 147 0.18 n.t. –

Residue 1–2 2.28 10 2.17 46.4 64.8

Hydrolysis (2) 2.12 49 1.60 55.3 56.9