Prediction of pH in Model Systems Pressurized with Carbon Dioxide

Mathematical models were developed to predict the pH of model liquid food systems (pure water, ascorbic acid‐water, citric acid‐water, and ascorbic acid‐citric acid‐water) pressurized with carbon dioxide, as functions of pressure (0–34.50 MPa), temperature (32,37, and 42° C), and component concentrations [(0–1.107) X10−3 M for ascorbic acid, (0 to 6.080) × 10−4 M for citric acid]. For all simulation systems, predicted pH values closely followed experimentally measured pH values. In the pure water‐CO2 systems, pH was a strong function of pressure but a weak function of temperature. In ascorbic acid‐water‐CO2, citric acid‐water‐CO2, and ascorbic acid‐citric acid‐water‐CO2 systems, pH was relatively insensitive to CO2 pressure and was a strong function of acid concentrations. This method could be a first step toward predicting the pH of orange juice and other liquid food systems under pressurized CO2.