Experiment on inhibition of watermelon juice browning by high pressure carbon dioxide

In order to study the inactivation of peroxidase (POD) from watermelon juice by non-thermal technology, the effects of high pressure carbon dioxide (HPCD) treatment on POD activity, color, browning degree, lycopene content, and total polyphenol content of watermelon juice were investigated. In this study, HPCD treatment was performed at 50℃ under 8, 15, 22, and 30 MPa, and the treatment time of 2.5, 5, 10, 20, 30 min was applied at each pressure compared to thermal treatment of 50℃. Results showed that HPCD treatment not only inactivated POD activity, but also reduced browning degree of watermelon juice. After HPCD treatment, the content of lycopene reduced slightly (P＜0.05), total phenol remained constant (P＞0.05). Moreover, the correlation analysis presented that browning degree of watermelon juice showed positive relation with its POD residual rate, and negative relation with its L* value. And HPCD treatment of 50 ℃, 30 MPa, and 30 min was the better production condition of watermelon juice. Hence, HPCD treatment could inhibit browning of watermelon juice by inactivating POD activity in production. .