INTERESTERIFICATION OF PALM MIDFRACTION AND STEARIC ACID WITH RHIZOPUS ARRHIZUS LIPASE UNDER CONTROLLED WATER ACTIVITY

摘要

The interesterification of palm oil midfraction (POMF) and stearic acid with Rhizopus arrhizus lipase immobilized on Celite was carried out in n-hexane. The water activity of the system was controlled by equilibrating the immobilized enzyme and substrate solution, separately, with a saturated salt solution of known water activity for at least 24 hours. The effects of water activity and enzyme loading on the interesterification reaction between POME and stearic acid were investigated. It was found that a combination of water activity=0.432, enzyme loading=10.33 U/mg Celite yields optimal interesterification activity. The effects of molar ratio of stearic acid to POMF and substrate concentration on the interesterification reaction were also examined. The half-life of the storage stability at 4 degrees C was 26 days. [References: 12]