Enzymatic biosynthesis of ricinoleic acid estolides

Candida rugosa lipase has been shown to have sufficient activity to catalyse the enzymatic synthesis of ricinoleic acid estolides in a batch reactor. The water requirements of the reactor change during the reaction: at the beginning of the process a minimum amount of water is necessary but, later, the reaction mixture must be dried out to obtain an estolide with a high degree of condensation. The influence on the reaction rate of variables, such as water content, enzyme concentration and mixing devices, was established and optimised. Using an initial water content of 144,000 ppm and a lipase concentration of 13.33 mg E/g ricin, and maintaining the temperature at 40 °C by mean of hot air circulation and using a three-bladed propeller stirrer as mixing device, an estolide of ricinoleic acid with an acid number of 65 was obtained in 48 h.