Abstract
A naturally occurring immobilized rice bran lipase (IRB-L) prepared by a simply process of defatting for rice bran with organic solvent has been successfully developed. Low oil extraction possessed high activity of lipase was observed when the extraction ratio of acetone to rice bran was 20:1 used to defat. The hydrolytic activity of IRB-L increased from 3.87U/g to 12.8U/g at the optimum pH 10 and temperature 80℃. IRB-L retained 72% of its initial activity after 5 batch hydrolytic cycles. Broad pH tolerance and higher thermo-stable ability could be achieved for the IRB-L. After 45 days of storage at 40℃ or 4℃, the residual activity of the IRB-L was 81%. The kinetic parameters Km and Vmax for IRB-L were 36mM and 15.89 U/g. The activation energy 2.64kcal/gmole for IRB-L was observed lower than that of the other literatures reported which indicated a high affinity for the supports active site and lower sensitivity to temperature. In addition, about 80% of conversion was achieved when IRB-L used as a biocatalyst to hydrolyze the soybean oil and waste oil for 12hr and 72hr, respectively.