Kinetic/thermodynamic study of immobilized β-fructofuranosidase from Aspergillus tamarii URM4634 in chitosan beads and application on invert sugar production in packed bed reactor

Abstract

β-fructofuranosidase (FFase) from Aspergillus tamarii URM4634 was immobilized covalently in chitosan beads. It was characterized biochemically, studied in terms of kinetic and thermodynamic parameters, and applied on conversion of sucrose for invert sugar production in a packed bed reactor (PBR). The optimum reactional conditions were determined and obtained at pH 5.0 and 60 °C. FFase was thermostable at 50–55°C. At 50°C, the enzyme shows longer half-life (t1/2) (594.13 min) and a higher D-value (1,973.64 min). This indicates that immobilized FFase was stable at temperature commonly used in invert sugar production. The following thermodynamic parameters were obtained: activation energy (E*d = 301.57 kJ mol−1), enthalpy (298.76 ≤ ΔH*d ≤ 298.89 kJ mol−1), entropy (579.88 ≤ ΔS*d ≤ 589.27 J K−1 mol−1) and Gibbs free energy (100.29 ≤ ΔG*d ≤ 108.47 kJ mol−1). The high E*d, ΔH*d and ΔG*d values confirmed FFase thermostability. The high and positive values for ΔS*d indicate an increase in disorder due opening of the enzyme structure. The sucrose hydrolysis in PBR showed a maximum invert sugar yield (96.0%) at 15 min of operation. The hydrolysis process remained efficient up to 100 min (70.22%). The results obtained in the present study provide a good indication that immobilized FFase on chitosan beads in PBR is efficient to invert sugar production for food industry.