THE INFLUENCE of pH ON the KINETICS of ACID HYDROLYSIS of SUCROSE

Abstract

Sucrose acid hydrolysis was studied as a potential chemical time‐temperature integrator to use under pasteurization conditions. A nonisothermal method was used to determine the kinetic parameters of this reaction at different pH values in the range of 0.8 to 2.5 and covering the range of temperatures from 50 to 90G. the nonisothermal method was first validated with the classical two‐step isothermal method at pH 2.5. Kinetic parameters showed to be highly collinear (correlation of 0.99), but it was concluded that the activation energy can be assumed independent of pH and equal to 99 kJ/mole with the preexponential factor being proportional to the H+ concentration. Results are favorable for the future application of this system in the evaluation of pasteurization processes. Since the activation energy was found to be independent of the pH, this system is useful as a TTI for validation of mathematical models, but not so much for monitoring quality factors, except those with an equal activation energy.

Application of the acid hydrolysis of sucrose as a temperature indicator in continuous thermal processes

“…Sixteen non-isothermal experiments were conducted in the range of pH from 0.8 to 1.5, because the lowest value tested in the literature was 2.5. The experiments were conducted as described by Pinheiro Torres et al (1994), although using a linear temperature increase, from 50°C to 90°C. The heating rate was selected according to pH, so that approximately 90% reduction of the disaccharide was achieved in all experiments (Fig.…”

“…In addition, Adams, Simunovic and Smith (1984) applied this TTI in continuous thermal processes, focusing on UHT temperature ranges. Acid hydrolysis of sucrose was also proposed as a TTI for lower temperature processes, namely continuous pasteurisation (Pinheiro Torres, Oliveira, Silva & Fortuna, 1994), but no validation was presented in the literature.…”

Experimental validation of models for predicting optimal surface quality sterilization temperatures

“…This result corresponds to a z value of approximately 31°C in the temperature range 100-140°C. Pinheiro Torres et al (1994) concluded that this system could be used for monitoring quality factors (although only when the quality attribute kinetics has the same activation energy, as previously mentioned).…”

“…From an exhaustive study on the dependence of kinetic parameters on the pH value (in the range of pH 0.8 to 2.5 and temperatures of 40 to l W C ) , Pinheiro Torres et al (1994) concluded that the activation energy was 99kJmol-'. This result corresponds to a z value of approximately 31°C in the temperature range 100-140°C.…”

“…The non-isothermal experiments were carried out with a linearly increasing temperature profile, which gives equal statistical weight to all temperatures (Pinheiro Torres et al, 1994). With this procedure, the DT,,, and z values can be calculated from only one experiment where the concentration and temperature are simultaneously recorded as a function of time.…”