Modelling of the inactivation kinetics of Escherichia coli, Saccharomyces cerevisiae and pectin methylesterase in orange juice treated with ultrasonic-assisted supercritical carbon dioxide

• HPU enhanced the SC-CO2 inactivation of microorganisms and enzymes in orange juice.
• The effect of HPU depended on the type of microorganism and the nature of the medium.
• The effect of increasing pressure or temperature depended on the nature of the medium.
• The combined SC-CO2 and HPU process permits the use of mild process conditions.
• SC-CO2 + HPU allows using shorter process times for a given inactivation level.

The combined effect of supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) on the inactivation kinetics of Escherichia coli, Saccharomyces cerevisiae and pectin-methyl esterase (PME) in orange juice was studied in order to select models that can predict their inactivation behaviour based on process parameters. Experiments were performed at different temperatures (31–41 °C, 225 bar) and pressures (100–350 bar, 36 °C). The inactivation rate of E. coli, S. cerevisiae and PME increased with pressure and temperature during SC-CO2 + HPU treatments. The SC-CO2 + HPU inactivation kinetics of E. coli, S. cerevisiae and PME were represented by models that included temperature, pressure and treatment time as variables, based on the Biphasic, the Peleg Type B, and the fractional models, respectively. The HPU-assisted SC-CO2 batch system permits the use of mild process conditions and treatment times that can be even shorter than those of continuous SC-CO2 systems.

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