Kinetic Analysis of a Crude Enzyme Extract Produced via Solid State Fermentation of Bakery Waste

In this study, glucoamylase extract was produced from various bakery wastes under solid state fermentation by Aspergillus awamori and Aspergillus oryzae. The highest glucoamylase activities obtained from bread and cake waste with A. awamori were 240.7 U/g of bread (db) and 134.9 U/g of cake (db), respectively, and 83.3 U/g of pastry (db) using A. oryzae. Kinetic studies showed that glucoamylase obtained from bakery wastes should have at least two conformations under the two temperature ranges of 30-55 degrees C and 60-70 degrees C. Thermodynamics stated that the range 30-55 degrees C was considered to be the optimal temperature for glucoamylase activity and subsequent food waste hydrolysis. The crude enzyme extracts were then used in the hydrolysis of restaurant food waste to produce a glucose-rich hydrolysate. It was found that using combined crude glucoamylase (produced from A. awamori and A. oryzae) could achieve higher glucose production (0.515 g of glucose/g of food waste) than using glucoamylase alone (produced from A. awamori). Results obtained from this study demonstrate that the proposed bioprocess could be successfully applied for the bioconversion of food waste into value-added products in a sustainable way.