The Preparation of High-purity Crystalline Glucose and Soluble Dietary Fiber through Enzymolysis of Sweet Potato Residue

A practical method for preparing high-purity crystalline glucose through enzymolysis of sweet potato residue was developed. Freshly prepared sweet potato residue, mixed with water of equal volume, was first treated with 20 U/g thermostable α-amylase at 90 ℃ for 60 min and then with 300 U/g glucoamylase at 60 ℃ for 6 h. The hydrolyzed glucose solution was treated with 1% macroporous resin to remove the impurities, vacuum-concentrated to glucose content of 70%, and crystallized at 4 ℃ for 48 h. After being washed twice with 95% ethanol and vacuum-dried, crystallized glucose with purity higher than 99% was obtained. After hydrolysis, the remaining sweet potato residue was mixed with 150 U/g cellulase and reacted at pH 5.5 and 40 ℃ for 180 min. The yield of soluble dietary fiber increased from 2% to 20%. This research provides a simple and practical method for efficient utilization of sweet potato residue and reduction of resource waste and ecological pollution.