Glucoamylase Immobilization in Corncob Powder: Assessment of Enzymatic Hydrolysis of Starch in the Production of Glucose

Abstract

Purpose: Amylases are environmentally attractive enzymes and are employed in food processing technology; for example, the starch hydrolysis process is used for glucose syrup production. The use of biocatalysts attached to a support promotes greater stabilization of the enzyme and allows its reuse, this being interesting for industrial applications. The choice of the support for enzyme immobilization must be made according to the process costs, therefore, the employment of agro-industrial byproducts is an alternative. We evaluated the immobilization of commercial glucoamylase in corncob powder (CCP) and the application of the immobilized enzyme (CCP-glucoamylase) in response to starch hydrolysis process Results: The yield of glucoamylase immobilization in CCP was 95%. Soluble glucoamylase and CCP-glucoamylase presented maximum activity temperatures at 50 °C and 60 °C, respectively. Both biocatalysts showed a maximum activity at pH 5. Soluble glucoamylase and CCP-glucoamylase exhibited a good thermal stability at 50 °C, resulting in half-lives of 33 h and 46 h, respectively. Soluble glucoamylase and CCP-glucoamylase reached starch conversion into glucose of 75% and 16%, respectively, after 12 h of reaction, with an enzymatic load of 30 U per gram of starch. However, after an increase in the enzymatic load of CCP-glucoamylase, starch conversion was equivalent Conclusion: CCP-glucoamylase has the potential to hydrolyze starch into glucose and can be reused, thus becoming an enhanced value-added bioproduct and an alternative for industrial applications. A strategy for future industrial application would be the hydrolysis of starch using CCP-glucoamylase in a fixed bed reactor operated continuously. Graphic Abstract: [Figure not available: see fulltext.]