Inactivation of E.coli using a continuous flow ultrasound-assisted supercritical CO2 system

Autores UPV
CONGRESO Inactivation of E.coli using a continuous flow ultrasound-assisted supercritical CO2 system


Supercritical carbon dioxide (SC-CO2) inactivation technology represents a promising non-thermal processing method, as it promotes minimum impact on the nutritional food properties. However, in some cases high pressures or temperatures and too long treatment times are required to guarantee the food¿s safety. In order to obtain the required lethality at shorter processing times, a combination of SC-CO2 with high power ultrasound (HPU) has been studied. The results showed that the combination of both techniques in a batch system accelerated the death of E. coli compared with the use of only SC-CO2. The objective of this work was to study the combined effect of SC-CO2 and HPU on E. coli inoculated in commercial apple juice, approximately 108 CFU and treated in a continuous system. The influence of the pressure, temperature and retention time on the inactivation process was evaluated. Experiments were performed at different temperatures (31, 36 and 41 °C), pressures (100-200 bar) and retention times (1.72, 2.58 and 5.44 min).The application of HPU significantly (p<0.05) influenced the inactivation rate. Using SC-CO2 (100 bar, 31 ºC) for 2.58 min was required to achieve 3.29 log-cycles of reduction while using SC-CO2+HPU (100 bar, 31 ºC, 2.58 min), a reduction of 7.42 log-cycles was obtained. The inactivation rate of E. coli increased as pressure and retention time increased during the SC-CO2 +HPU treatments, at 31 ºC and 100 bar a reduction of 8 log-cycles was achieved at 5.44 min compared with only 4.4 logcycles obtained at 1.79 min. No significant (p<0.05) effect of temperature was found at the different process conditions. The results demonstrated the potential of the continuous SC-CO2 +HPU inactivation technique, the use of mild process conditions could lead to an increase in the quality of the product treated under this technique.