ISSN:
0178-515X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract In this work different aspects of the glucose-fructose enzymatic isomerization, using immobilized glucose isomerase, are studied and quantified. Reaction temperatures range from 40 °C to 60 °C. Intra-particle effective diffusivities (D e), determined after uptake experiments, are between 1.20 × 10−6 cm2/s, at 40 °C, and 2.52 × 10−6 cm2/s, at 60 °C. The estimated energy of activation for diffusion (E aD) is 7.71 kcal/mol. No significant adsorption of the sugars on the support gel matrix is observed. Crushed particles (φ = 150–350 μ) are used during kinetic experiments. For this range of particle diameters, inherent kinetics is approached. A reversible Michaelis–Menten rate equation is fitted to the data, providing the following parameters at pH = 7.0: k 0 = 2.15 × 10−6 g/IU/s; E a/R = 8998 K. Glucose (K G) and fructose (K F) affinity constants are essentially the same, ranging from 0.190 M, at 40 °C to 0.305 M, at 60 °C. The thermodynamic equilibrium constant is determined for the three temperatures, and the heat of reaction, estimated from a Van't Hoff plot, is ΔH = 1682 cal/mol. Independent experiments, where the reaction occurs in the presence of significant intra-particle mass transfer resistance, are used as validation tests.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004499900142
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