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.