Herein, we describe the use of high-pressure CO2 for the inactivation of the natural bio-burden of paprika and an evaluation of its effects on product quality. The treatments were carried out with a continuous flow Of CO2 through a bed of paprika, varying the initial moisture (<35%), pressure (60-300 bar), temperature (<95 degrees C) and exposure time (10-150 min). Comparison was made with thermal treatment at the same temperature and moisture levels to isolate the effects of the CO2. It was difficult to achieve a total elimination of the highly resistant spores due to the low water activity of the medium. The paprika did not appear to exert a protective effect. Neither the use of techniques to improve the CO2-paprika contact nor pressure cycling had any effect. The most influential parameters were the initial water content and temperature, presumably due to their contributions to the activation/germination of spores, making these microbes vulnerable to CO2 attack. However, we found that their values should be kept under 25-30% and 85-90 degrees C, respectively, to avoid a loss of product quality. Pressure could be maintained at relatively low levels (60-100 bar) because it did not significantly contribute to any of the possible CO2 sporicidal mechanisms and at higher values caused oleoresin extraction. Under these conditions, treatment times on the order of 30-45 min were sufficient to achieve the disinfection and total count reduction required by the most exigent clients. The treated paprika retained its colour category and its final humidity was within the legal levels for secure storage. Therefore, the method could be a useful alternative to traditional moist-heat treatments or hydrostatic processes. (C) 2009 Elsevier B.V. All rights reserved.