Inactivation of pectinesterase in valencia orange juice by micro-bubble supercritical carbon dioxide method

For the purpose of inactivation of pectinesterase (PE), Valencia orange juice was treated by micro-bubble supercritical carbon dioxide (SC CO₂) method. Three cylindrical micro-pore filters (2, 7 and 10 μm pore size) were tested for efficiency of the treatment. Among them, the filter (10 μm pore size) could yield the highest CO₂ concentration (0.92 mol/l at starting time) in a sample solution, so that the efficiency of inactivation was greatly improved. After the treatment at 25 MPa and 35°C for 30 min, residual activity of PE decreased from 43.1% (without the filter) to 6.1% (with the filter). The following results were obtained with the filter. At each treatment temperature of 35, 45 and 55°C, higher pressure and/or prolonged treatment time caused greater decrease of PE activity. Especially, the large inactivation was observed at 35°C. The residual activity-CO₂ density profile showed the abrupt decrease of the activity when the CO₂ density was above 0.79 g/cm³.