Effects of a combined process of high-pressure carbon dioxide and high hydrostatic pressure on the quality of carrot juice

A combined treatment of high-pressure carbon dioxide (HPCD) and high hydrostatic pressure (HHP) was investigated as a non-thermal processing technique to enhance the safety and shelf life of carrot juice. Aerobes were completely inactivated by a combined treatment of 4.90 MPa-HPCD and 300 MPa-HHP. A combined treatment of 4.90 MPa-HPCD and 600 MPa-HHP effectively inactivated enzymes. The residual activities of polyphenoloxidase, lipoxygenase, and pectinmethylesterase were less than 11.3%, 8.8%, and 35.1%, respectively. Cloud and color were considerably affected by HPCD, but not by HHP. Enzyme activities and the total color difference showed a strong correlation with pH, which was dependent on the pressure of carbon dioxide.