In this study, we evaluated the influence of CO2 volume ratio (%) and its synergic effect with the pressure (MPa), temperature (degrees C) and process time (min) on the inactivation of Lactobacillus casei cells inoculated in apple juice (10(7) CFU/mL). The effects of process variables on the logarithmic reduction of L. casei cell counts were estimated by a two-level Plackett-Burman factorial design. A Box-Behnken design was subsequently employed to evaluate the interaction between the different factors on the supercritical microbial inactivation. The results showed that the process intensification led to a higher logarithmic reduction. Operating at 15 MPa, 55 degrees C, 30 min and a 70% CO2 volume ratio, the process was able to reduce L. casei cell counts by more than 6 log cycles. In addition, this work reports the validation of an experimental apparatus assembled by our research group for food processing by employing supercritical carbon dioxide.