Highly efficient glucose production from raw non-pretreated Chinese medicinal herbal residues via the synergism of cellulase and amylolytic enzymes

•The four investigated CMHRs contained varied starch content.•Combined cellulase and amylolytic enzymes significantly improved CMHR hydrolysis.•Pretreatments by solvent, ultrasound and acid decreased glucan conversion.•Alkaline pretreatment increased glucan conversion but incurred additional costs.•Hydrolysis of raw CMHRs with combined enzymes seemed to be a preferred option.