Combined effect of high pressure carbon dioxide and mild heat treatment on overall quality parameters of watermelon juice

The aim of this study was to investigate the combined effect of high pressure carbon dioxide (HPCD) and mild heat treatment on the overall quality of watermelon juice. The residual activity of polyphenoloxidase (PPO), peroxidase (POD), and pectin methylesterase (PME) decreased with pressure and treatment time after HPCD and heat treatment. The total color difference (△E) value was greater than 3.5, suggesting the significant change of color. Browning degree (BD) decreased with pressure and treatment time; pH and lycopene content of HPCD-treated juice slightly decreased; cloudiness and titratable acidity (TA) increased; and viscosity of 10 and 20 MPa treated juice at 31.62 1 s− 1 did not change. While after control treatment, the residual activity of enzymes and BD decreased slightly; cloudiness decreased greatly; pH, TA, lycopene content, and color were stable. HPCD and mild heat treatment inactivated enzyme activities drastically which affected the shelf life and quality of watermelon juice greatly during storage. And it increased cloudy stability that was the important parameter to influence appearance of juice. Overall, HPCD treatment has greater advantages to maintain the quality of watermelon juice.Industrial relevanceThe application of high pressure carbon dioxide (HPCD) processing on several food products has already been proven to be successful for pasteurization. HPCD processing to inactivate endogenous enzymes and retain quality of food needs to be further studied. Studies dealing with the combination effect of pressure and mild heat conditions on enzyme activities and quality parameters are relevant to understand the prospects for watermelon juice processing.

► We applied high pressure carbon dioxide (HPCD) on watermelon juice.
► We studied the quality parameters of watermelon juice after HPCD treatment systematically and evaluated the impact on juice.
► We found the different trend of polyphenol oxidase and peroxidase activity of watermelon juice after HPCD treatment with previous studies.