Process Study on Enzymatic Hydrolysis of Crambe Oil for Erucic Acid Isolation

Abstract

High erucic acid (HEA) seed oils can be processed enzymatically to produce biodiesel and erucic acid (EA), a valuable industrial feedstock. This study aimed to conduct a research on an effective reaction pathway to isolate EA from other fatty acids in HEA oils utilizing appropriate lipase specificities. Crambe oil was chosen as the model working feedstock. Rhizomucor miehei lipase was chosen to selectively hydrolyze crambe oil to liberate EA from the HEA oil directly into free EA. The effects of reaction parameters, including water content, lipase concentration, mixing intensity, and reaction temperature, were studied. Experimental results of an orthogonal design showed that the effect of process parameters was significant for the reaction rate, but insignificant for the reaction selectivity. Further statistical analysis revealed that lipase concentration had the most significant effect on the reaction rate, while water content showed a negative effect on the hydrolysis. Individual effects of aqueous phase ratio, initial lipase concentration, and mixing intensity were further investigated separately at the optimal lipase activity temperature. Results showed that water played a role mainly in affecting the specific interfacial area in the heterogeneous process of crambe oil hydrolysis. The interfacial reaction rate increased with the increase in initial lipase concentration, but was limited by a critical value. Mixing intensity affected the hydrolysis to a certain extent and then leveled off due to the lack of further size reduction of the discrete phase.