Front Matter

9.4 Examples of syntheses of pure sTAG containing

PUFA

Among a number of reactions to produce sTAGs, only reactions involving PUFA

biotransformations are discussed here. These are classified into two types: (i) reac-

tions involving natural edible oils (vegetable oil or fish oil); and (ii) reactions be-

tween chemically defined pure TAG and pure FA or FA esters. Reports dealing with

the former are summarized in Table 4. In the following only reactions between che-

mically defined pure TAG and pure FA or FA esters are discussed.

9.4.1 AAB-type sTAG

Hanet al.have recently studied the reaction in a solvent-free system (Han et al.,

1999a,b; Han and Yamane, 1999) [Equation (6)]:

EPAEE + C 8 C 8 C 8 R(EPA)C 8 C 8 [and/or C 8 C 8 (EPA)] + C 8 EE (6)

Three microbial lipases (fungal, yeast and bacterial) were tested for the formation of

the pure targeted product (Han et al., 1999a), and a fungal lipase (Rhizomucor mie-

hei) was proven to give almost pure AAB type sTAG. An investigation of the molar

ratio of EPAEE to tricaprylin in the range of 1 : 1 to 1 : 5, the ratio of 1 : 3 gave the

highest yield (ca. 90 %). The influence of the temperature was also studied and

showed that the selectivity of the lipase seemed to decrease slightly at higher tem-

peratures. Also, the initial awaffected the yield significantly. A vacuum was applied

to shift the reaction equilibrium toward synthesis reaction by removing C 8 EE. While

applying vacuum, the water level of the reaction system was controlled to the optimal

level by addition of suitable amounts of water at predetermined time intervals. Inter-

mittent periodical addition of suitable amounts of water made the reaction faster and

enabled a higher final yield (Figure 5) (Han and Yamane, 1999). Using awcontrol, the

yield of the targeted sTAG reached 90 % after 16 h.

9.4 Examples of syntheses of pure sTAG containing PUFA 163

Table 4.Synthesis of sTAG containing PUFA from natural edible oils.

Substrates Enzyme source Immobilization Reference

Tuna oil + caprylic acid Rhizopus delemar Ceramic carrier Shimada et al., 1996a

Borage oil + caprylic acid Rhizopus delemar Ceramic carrier Shimada et al., 1999

Single cell oil + caprylic
acid

Rhizomucor miehei Macroporous

ionic resin

Iwasaki et al., 1999

Fish oil + tricaprylin Candida antarctica? Lee and Akoh, 1998