Cane Pretreatment by Deep Eutectic Solvents to Increase its Reactivity During Enzymatic Hydrolysis with Cellulases

Cane was pretreated with a number of deep eutectic solvents (DESs) based on choline chloride (ChCl) as a hydrogen bond acceptor. Among hydrogen bond donors, lactic (LA) and oxalic (OA) acids were the most effective. Substrate pretreatment conditions (ratio of DES-components, temperature and exposure time) were optimized, which resulted in the highest yield of reducing sugars (RS) and glucose during subsequent enzymatic hydrolysis with cellulase preparation based on Penicillium verruculosum. It was established that in the case of a mixture of ChCl with LA (the molar ratio of components was 1 : 5) pretreatment should be carried out at 80°C for 24 hours, and in the case of a mixture of ChCl with OA (1 : 1), optimal conditions were 80°C and 6 hours. The degree of conversion of the pretreated substrate after 48 hours of hydrolysis in the presence of the enzyme preparation (EP) B537 was 80 and 86% by absolutely dry substances for selected mixtures of ChCl/LA and ChCl/OA, respectively.