Enzymatic transesterification of palm olein in organic solvent was studied.
The enzyme was first immobilised to celite, lyophilised for 4 h and then added to a
reaction medium composed of water-saturated hexane containing of 10% (w/v) palm
olein. The catalytic performance of the enzyme was evaluated by determining
changes in the triglycerides (TG) composition and concentration by reverse-phase
high performance liquid chromatography (RP-HPLC) and the formation of free fatty
acids (FF A) by titration, respectively. For Candida rugosa lipase, the optimal water
content was controlled by lyophilisation of the lipase preparation for 4 h. The
addition of water to the dried immobilised preparation shifted the reaction
equilibrium to favour net hydrolysis. Of the commercially available lipases that were
investigated, lipases from Pseudomonas sp. and the lipase from Rhizomucor miehei resulted in the highest extent of transesterification. Besides palm olein, palm kernel
olein and coconut oil showed some changes in the triglyceride composition after
transesterification process. Changes in the palm olein concentration in the range 5-
1 00% increased the degree of transesterification of the immobilised Pseudomonas sp.
and declined with the R. miehei lipase. The maximum enzyme activity was reached at
an enzyme loading of 0.40% (w/w). The optimum temperature for trans esterification
by immobilised Pseudomonas sp. lipase was 48°C. Hexane, cyclohexane and
isooctane were found to be particularly useful organic solvents in the
transesterification process. Water-saturated hexane system can be replaced by either
dimethysulfoxide- or dimethylformamide-saturated hexane. Methanol was not
suitable for the transesterification process. In all cases, the transesterification
process resulted in the formation of PPP (tripalmitin), a trisaturated triglyceride
initially undetected in the oil, and minor increases in the concentration of 000,
OOL, OLL, SOS, where P, 0, L and S are palmitic, oleic, linoleic and stearic acid,
respectively thus increasing the slip melting point of the final product