Orange juice (OJ) was treated with a continuous high‐pressure carbon dioxide (HPCD) system, and the quality parameters pH, Brix, titratable acidity (TA), cloud, pectinesterase (PE) activity, color, and sensory attributes were determined. Treatment pressures were 38, 72, and 107 MPa, and CO2/juice (w/w) ratios were from 0.40 to 1.18. Residence time was kept at 10 min. Cloud increased between 446% and 846% after treatments. There were no significant changes in pH and Brix (α= 0.05). TA of the treated juice was found to be significantly different from that of control (α= 0.01). PE was not completely inactivated. There was a small, but significant increase in juice L‐value (α= 0.01) and a decrease in a‐value for color. There was no significant change in b‐values (α= 0.05). Statistical analysis for the sensory data showed no difference between fresh, frozen control juice and treated juice after 2 wk of refrigerated storage at 1.7 °C.

: A continuous high‐pressure carbon dioxide system, run at ambient conditions, was tested on its performance in reducing both natural and inoculated microbial loads. The prototype system continuously processes orange juice with carbon dioxide (CO2) at high pressures. A central composite design was originally used to examine the variables of pressure, residence time, and CO2/juice ratio. For microbial reduction, residence time was the major factor followed by pressure. The CO2/juice ratio showed no influence on microbial load, and in this equipment, was difficult to control. The unit was able to cause a 5‐log reduction of the natural flora in spoiled juice, and could attain a 5‐log decrease in numbers of pathogenic Escherichia coli O157:H7, Salmonella typhimurium, and Listeriamonocytogenes. No viable cells of E. coli O157:H7 orS. typhimurium were cultured after the treated juices were stored at room temperature (22 °C) for 14 d. Thus, non‐thermal pathogen reduction is possible with this system.