抄録
Triglyceride docosahexanoic acid (DHA) was produced by the hydrolysis of natural marine lipids containing triacylglycerols. Marine lipids, which contain poly-unsaturated fatty acids (PUFA) such as docosahexanoic acid can potentially be used as nutritional additives for human consumption. These compounds have been shown to be useful for preventing several diseases. Lipase was effective as a biocatalyst, facilitating the hydrolysis of triglycerides and subsequent production of DHA. Candida rugosa type lipase was used in our reaction system. Ester-bonded DHAs in the triglycerides were not hydrolyzed by the lipases used in our experiments, because of steric hindrance of the substrate. In contrast, the mono unsaturated fatty acids in triglyceride were easily hydrolyzed, and were efficiently separated during the lipase reaction. Using this system of lipase-catalyzed hydrolysis, triglyceride-DHA can be produced efficiently and with a high yield. The W/O microemulsion system described here, employing soybean lecithin as an amphiphile, was used as a biocompatible reaction medium. Phosphate buffer (6.0≤pH≤7.5) was used as the aqueous phase, and 2-2-4 trimethylpentane (isooctane) was used as the organic solvent. The initial reaction rate, which provided an indicator of lipase reactivity, increased dramatically with increasing water content over the range from 5≤W0≤10, and then reached a maximum level at a W0 value of 10. The molar ratio of water to lecithin (W0)was also used as a measure of water content. The optimal lecithin concentration was found to be 12mM. The results of this study suggest that lecithin was superior to AOT since higher initial reaction rates were achieved. The optimal temperature for the reaction was found to be 316K (43°C). The activation energy for the reaction was measured at 135kJ/mol.
