The Journal of Supercritical Fluids vol:55 issue:1 pages:77-85
High-pressure carbon dioxide (HPCD) treatment is currently considered as an attractive non-thermal process for preserving food. Since the first level of interaction between HPCD and the bacterial cells is lowering of the pH, knowledge of the pH of a food product in contact with CO2 at high-pressure conditions is essential for a better understanding of the inactivation mechanism of HPCD. Therefore, a mathematical model was developed to predict the pH in complex aqueous food systems in contact with CO2 at high-pressure conditions as function of pressure, temperature and buffer capacity. In addition, a spectrofluorometric method using calcein as fluorescent pH indicator was designed for the in situ measurement of the pH of complex aqueous systems in contact with pressurized CO2 as function of pressure (10.5-18.0 MPa), temperature (25-35 degrees C), initial pH (4.0-8.0), working volume ratio (41.6-70.0%) and broth composition (0.1 M citrate buffer, 0.1 M phosphate buffer and 10% whey protein). To mimic a complex matrix, the bacterial Brain Heart Infusion (BHI) broth was used.