Inactivation of Alicyclobacillus acidoterrestris spores by high pressure CO2 in apple cream

Alicyclobacillus acidoterrestris (A. acidoterrestris) is a bacillus-type spore former that causes significant alterations in fruit products. It is highly resistant to typical pasteurization regimes; thus, this work explored the use of high-pressure CO2 (HPCD) for its deactivation in apple cream. The assays were conducted in a high-pressure apparatus where the cream was placed in an agitated vessel and the CO2 passed over under different operating conditions for distinct periods of time. The HPCD was able to deactivate the A. acidoterrestris spores in the apple cream by four orders of magnitude at 30 °C and 10 MPa. On the other hand, the lethal effect of HPCD was independent of the thermal effect since the application of dry heat without CO2 at the same temperature did not cause any A. acidoterrestris deactivation. The important variables in terms of improving the method were the flow regime and the way to put in contact the HPCD and the cream. Finally, the HPCD treatment did not affect the most important sensorial and rheological properties of the cream; although there was a slight reduction in the vitamin C content due to thermal degradation.