title: Isoglucose production from raw starchy materials based on a two-stage enzymatic system.
abstract: A new low-cost glucoamylase preparation for liquefaction and saccharification of starchy raw materials in a one-stage system was developed and characterized. A non-purified biocatalyst with a glucoamylase activity of 3.11 U/mg, an alpha-amylase activity of 0.12 WU/mg and a protein content of 0.04 mg protein/mg was obtained from a shaken-flask culture of the strain Aspergillus niger C-IV-4. Factors influencing the enzymatic hydrolysis of starchy materials such as reaction time, temperature and enzyme and substrate concentration were standardized to maximize the yield of glucose syrup. Thus, a 90% conversion of 5% starch, a 67.5% conversion of 5% potato flour and a 55% conversion of 5% wheat flour to sweet syrups containing up to 87% glucose was reached in 3 h using 1.24 glucoamylase U/mg hydrolyzed substrate. The application of such glucoamylase preparation and a commercially immobilized glucose isomerase for the production of glucose-fructose syrup in a two-stage system resulted in high production of stable glucose/fructose blends with a fructose content of 50%. A high concentration of fructose in obtained sweet syrups was achieved when isomerization was performed both in a batch and repeated batch process.
authors.affiliation: Faculty of Biology and Earth Sciences, Institute of Microbiology and Biotechnology, Department of Industrial Microbiology, Maria Curie-Skłodowska University, Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Gromada
authors.forename: Jan
authors.initials: J
authors.lastname: Fiedurek
authors.forename: Janusz
authors.initials: J
authors.lastname: Szczodrak
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000378:metabolism; D001234:Aspergillus niger / Q000201:enzymology* / Q000378:metabolism; D003470:Culture Media; D004800:Enzymes, Immobilized / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D005632:Fructose / Q000378:metabolism; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006868:Hydrolysis; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D003470:Culture Media; D004800:Enzymes, Immobilized; D005632:Fructose; D013213:Starch; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D005947:Glucose