Lipids of Leaves and Seeds Part III

Enzymatic Hydrolysis of Rice Bran Lipids

Abstract

Lipase activity increased in rice bran stored at higher humidity. Its complete inhibition was impossible even when stored at -20°C. There was an increase in lipase activity of bran from rice grain on long storage.
A purified lipase preparation was obtained from rice bran and it hydrolyzed rice bran lipids at pH optimums of 5.6 and 6.6 to 7.0. The activity was stable at 40°C, but declined rapidly at temperatures over 40°C. Calcium ion accelerated the hydrolysis at lower concentrations. Addition of ovalbumin to the incubation mixture activated the hydrolysis, whereas the inhibition was observed when phytin was added. The enzyme had no positional specificity for ester bonds of rice bran triglycerides and seemed to hydrolyze them accompanying acyl migration and re-esterification to some extent.