Optimization of Biocatalytic Rhododendrol Production from Biogenic Rhododendrol Glycosides

An enzyme-catalyzed synthesis of rhododendrol, an intermediate in the production of raspberry ketone, was investigated. The approach involves the enzymatic hydrolysis of rhododendrol glycosides into rhododendrol and a glycosidic residue. Rhododendrol glycosides, which are naturally derived from the inner bark of birch trees-a renewable resource-vary considerably in composition depending on the origin of the plants. In this study, mixtures of betuloside and apiosylrhododendrin from natural resources were used in different proportions. An in-depth study was conducted to assess the feasibility of the process. A mathematical model was developed based on studies of the kinetics and operational stability of the enzyme. The model for betuloside hydrolysis catalyzed by β-glucosidase was validated in batch, repetitive batch, and ultrafiltration membrane reactors. The highest productivity, ranging from 83.9 to 94.5 g L^-1 day^-1, was achieved in the latter. After screening nearly 50 enzymes, RAPIDASE emerged as a solution for the hydrolysis of apiosylrhododendrin, and the model was validated in a batch reactor. Model-based optimization enabled the prediction of input parameters for different compositions of biogenic rhododendrol glycosides to obtain consistent process output metrics.