Supercritical Carbon Dioxide solubility measurement in complex solutions

The use of Supercritical Carbon Dioxide (SC-CO2) for pasteurization of food has many advantages. Compared to the conventional thermal treatments it allows to work at milder temperature conditions (35-45°C). This helps preserve the organoleptic properties and nutritional attributes, usually lost during thermal treatments. Even if the microbial inactivation mechanism of SC-CO2 has yet to be completely understood, several studies proved that the efficiency of this treatment depends on the solubility of CO2 within the food matrix. During the treatment, dissolved SC-CO2 diffuses in the extracellular environment and reaches microbial cells. Understanding the behaviour of solubility would allow the optimization of this technique, as this aspect has not been fully explored yet. The scope of this project is to investigate the solubility of Supercritical Carbon Dioxide in water and complex solutions, resembling fruit juice composition, at different pressures and temperatures. The final objective is a description, through a mathematical model, of the behaviour of solubility of Carbon Dioxide. The study will be divided into two parts. In the first part, a method to measure CO2 solubility is set up and validated using pure water. Results will be compared to literature data to validate the method. In the second part, the method will be applied to measure CO2 solubility on different complex solutions containing glucose, sodium chloride, and citric acid. The experimental plan is arranged using a half factorial Design of Experiments (DoE) procedure. This allows to plan experimental tests and assess the linear influence of each of the factors considered (pressure, temperature and solutes) and their interactions on the response (solubility). The results are analysed through a response surface methodology which allows to obtain a mathematical model. The model then will be validated using new experimental data inside and outside the range of the factors in which the model was created.