Application of cellulase treatment in ionic liquid based enzyme-assisted extraction in combine with in-situ hydrolysis process for obtaining genipin from Eucommia ulmoides Olive barks

A new approach for ionic liquid based enzyme-assisted extraction coupled with in-situ hydrolysis (ILEIH) of geniposide from Eucommia ulmoides Olive barks is presented, in which enzymatic hydrolysis is used in an ionic liquid aqueous medium to prepare genipin. The method relied on the use of single cellulase to the extract and hydrolyze geniposide, which is performed continuously in the same system; genipin is easy in preparation with exempting the isolation and purification of geniposide. The mechanism of ILEIH procedure was discussed in detail to illustrate the advantage of ILEIH in the extraction process. 0.5 mol/L [C6mim]Cl aqueous solution was selected as extraction solvent. The optimum conditions of 140 min treatment time, 19.81 mL/g liquid-solid ratio, 5.15 mg/mL enzyme concentration and 5.0 pH value for the ILEIH process were obtained after investigating by single factor experiments and Box-Benhnken design in terms of the genipin increment. And the first-order kinetic model based on β-glucosidase in the three reaction medium were established to study their impacts on the reaction rate. The proposed ILEIH method was validated by stability, repeatability, and recovery experiments and shows reliable data in the extraction and hydrolysis process. Therefore, this proposed approach is promising for the in-situ production of genipin and should be potentially applied to the obtaining of other active aglycons.