Isoglucose production from raw starchy materials based on a two-stage enzymatic system

• Published in: Polish journal of microbiology 2008, Vol.57 (2), p.141-148
• Main Authors: Gromada, Anna, Fiedurek, Jan, Szczodrak, Janusz
• Format: Article
• Language: English
• Subjects: Aldose-Ketose Isomerases - metabolism; alpha-Amylases - metabolism; Aspergillus niger; Aspergillus niger - enzymology; Aspergillus niger - metabolism; Culture Media; Enzymes, Immobilized - metabolism; Fermentation; Food Microbiology; Fructose - metabolism; Glucan 1,4-alpha-Glucosidase - metabolism; Glucose - metabolism; Hydrolysis; Solanum tuberosum; Starch - metabolism; Triticum aestivum
• ISSN: 1733-1331; 2544-4646

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.