The demand of energy and the search for alternative energy sources are the reason why scientists are interested in starch hydrolysis. The aim of the work was to experimental study of the hydrolysis of starch by α–amylase from porcine pancreas with α–amylase deactivation. Based on the experiments data, the parameters of starch hydrolysis by α– amylase with deactivation of enzyme was estimated. A mathematical model of temperature impact on the activity of α–amylase from porcine pancreas was used. It has been estimated that the activation energy E_a and the deactivation energy E_d were equal to 66 ± 4 kJ/mol and 161 ± 12 kJ/mol, respectively. Additionally, specific constant of starch hydrolysis k ₀ and specific constant of α–amylase deactivation k _d0 were calculated. The optimum temperature T_opt equal to 318 ± 0.5 K was obtained from mathematical model. The obtained values of E_a, E_d, k ₀ and k _d0 parameters were used to the model starch hydrolysis by α–amylase from porcine pancreas at 310 K and 333 K.

The paper presents a comparative analysis to determine the optimal temperatures and the activation energies for various origin endo-inulinases from Aspergillus niger. The parameters were estimated based on the literature of the activity curves vs. temperature for hydrolysis of inulin. It was assumed that both the hydrolysis reaction process and the deactivation process of endo-inulinase were first-order reactions by the enzyme concentration. A mathematical model describing the effect of temperature on endo-inulinases from Aspergillus niger activity was used. Based on the comparison analysis, values of the activation energies Ea were in the range from 23:53  3:20 kJ/mol to 50:66  3:61 kJ/mol, the deactivation energies Ed were in the range from 88:42  5:03 kJ/mol to 142:87  2:75 kJ/mol and the optimum temperatures Topt were obtained in the range from 317:12  0:83 K to 332:55  0:72 for endo-inulinase A. niger.

Simplified optimization method using the MATLAB function fminbnd was adopted to determine the optimal feed temperature (OFT) for an isothermal packed-bed reactor (PBR) performing hydrogen peroxide decomposition (HPD) by immobilized Terminox Ultra catalase (TUC). The feed temperature was determined to maximize (minimize) the average reactant conversion (reactant concentration) over a fixed period time at the reactor outlet. The optimization was based on material balance and rate equation for enzyme action and decay and considered the effect of mass-transfer limitations on the system behavior. In order to highlight the relevance and applicability of the work reported here, the case of optimality under isothermal operating conditions is considered and the practical example is worked out. Optimisation method under consideration shows that inappropriate selection of the feed temperature may lead to a decrease in the bioreactor productivity.

On the basis of hydrogen peroxide decomposition process occurring in the bioreactor with fixed-bed of commercial catalase the optimal feed temperature was determined. This feed temperature was obtained by maximizing the time-average substrate conversion under constant feed flow rate and temperature constraints. In calculations, convection-diffusion-reaction immobilized enzyme fixed-bed bioreactor described by a coupled mass and energy balances as well as general kinetic equation for rate of enzyme deactivation was taken into consideration. This model is based on kinetic, hydrodynamic and mass-transfer parameters estimated in earlier work. The simulation showed that in the biotransformation with thermal deactivation of catalase optimal feed temperature is only affected by kinetic parameters for enzyme deactivation and decreases with increasing value of activation energy for deactivation. When catalase undergoes parallel deactivation the optimal feed temperature is strongly dependent on hydrogen peroxide feed concentration, feed flow rate and diffusional resistances expressed by biocatalyst effectiveness factor. It has been shown that the more significant diffusional resistances and the higher hydrogen peroxide conversions, the higher the optimal feed temperature is expected.

Optimal feed temperature was determined for a non-isothermal fixed-bed reactor performing hydrogen peroxide decomposition by immobilized Terminox Ultra catalase. This feed temperature was obtained by maximizing the average substrate conversion under constant feed flow rate and temperature constraints. In calculations, convection-diffusion-reaction immobilized enzyme fixed-bed reactor described by a set of partial differential equations was taken into account. It was based on kinetic, hydrodynamic and mass transfer parameters previously obtained in the process of H2O2 decomposition. The simulation showed the optimal feed temperature to be strongly dependent on hydrogen peroxide concentration, feed flow rate and diffusional resistances expressed by biocatalyst effectiveness factor.