The In-Silico Optimization of a Batch Reactor for D-Fructose Production by Using the Cetus Process with In-Situ Cofactor Quick Regeneration

Currently D-fructose (DF) is produced by enzymatic isomerization of beta-D-glucose (DG) under disadvantageous conditions (equilibrium conversion of 50%, costly fructose separation, glucose isomerase poor stability vs. impurities from preliminary starch saccharification). By contrast, the two-steps Cetus enzymatic process became a promising alternative to produce high purity DF. First, DG is oxidized to keto-glucose (kDG) using commercial pyranose 2-oxidase (P2Ox). To avoid the fast P2Ox inactivation by the in-situ produced hydrogen peroxide (H2O2), catalase is added to decompose this byproduct. The reaction is conducted at optimal pH = 6.5 and 25–35oC, with very high conversion and selectivity, leading to a product free of allergenic aldose compounds. Then, kDG is reduced to DF by using the NADPH cofactor, and aldose reductase (recombinant human - ALR), at 25oC and pH = 7. By using information from literature, this paper aims to check the continuously in-situ regeneration of NADPH cofactor by the expense of formate decomposition in the presence of formate dehydrogenase (FDH). By adopting a kinetic model from literature, this in-silico analysis determines the optimal operating conditions of a batch reactor (BR) used in the Cetus second step to maximize the DF production, by minimizing the costly [NADPH, ALR, FDH] consumption.