Kinetic studies on the multi-enzyme solution produced via solid state fermentation of waste bread by <i>Aspergillus awamori</i>

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Date

2013

Authors

Melikoğlu, Mehmet
Lin, Carol Sze Ki
Webb, Colin

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Elsevier Science Bv

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Energy Systems Engineering
(2009)
The Department of Energy Systems Engineering admitted its first students and started education in the academic year of 2009-2010 under Atılım University School of Engineering. In this Department, all kinds of energy are presented in modules (conventional energy, renewable energy, hydrogen energy, bio-energy, nuclear energy, energy planning and management) from their detection, production and procession; to their transfer and distribution. A need is to arise for a surge of energy systems engineers to ensure energy supply security and solve environmental issues as the most important problems of the fifty years to come. In addition, Energy Systems Engineering is becoming among the most important professions required in our country and worldwide, especially within the framework of the European Union harmonization process, and within the free market economy.

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Abstract

The aim of this study was kinetic analysis of the multi-enzyme solution produced from waste bread via solid state fermentation by Aspergillus awamori. It was found that at normal temperature for hydrolysis reactions, 60 degrees C, the activation energies for denaturation of A. awamori glucoamylase, 176.2 kJ/mol, and protease, 149.9 kJ/mol, are much higher than those for catalysis of bread starch, 46.3 kJ/mol, and protein, 36.8 kJ/mol. Kinetic studies showed that glucoamylase and protease in the multi-enzyme solution should have at least two conformations under the two temperature ranges: 30-55 degrees C and 60-70 degrees C. Thermodynamic analysis showed that, deactivation of glucoamylase and protease in the multi-enzyme solution can be reversible between 30 degrees C and 55 degrees C, since Delta S is negative and Delta H is positive. On the other hand, for glucoamylase and protease, both Delta S and Delta H are positive between 60 degrees C and 70 degrees C. This means that the deactivation of both enzymes in the multi-enzyme solution is spontaneous in this temperature range. It was also found that the glucoamylase produced in the solid state fermentation of waste bread is more thermally stable than the protease in the mixture. Consequently, the protease had little or no effect on the stability of the glucoamylase. Furthermore, the half-life of the glucoamylase produced from waste bread pieces was much higher than that produced from wheat flour. This is an important finding because the mode of production, via solid state fermentation, appears to have increased the thermostability of the enzyme significantly. (C) 2013 Elsevier B.V. All rights reserved.

Description

Webb, Colin/0000-0002-4094-2524; Lin, Carol Sze Ki/0000-0002-8493-4307

Keywords

Enzyme kinetics, Glucoamylase, Thermal deactivation, Protease, Waste bread

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Citation

55

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Q2

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Q2

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Volume

80

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Start Page

76

End Page

82

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