Comparison of high hydrostatic pressure and thermal processing on physicochemical and antioxidant properties of Maoberry (Antidesma thwaitesianum Muell. Arg.) juice

The alteration of microbiological, physicochemical and antioxidant properties of Maoberry (Antidesma thwaitesianum Muell. Arg.) juices after pressurization (400 or 600 MPa/25 degrees C/10 min) and pasteurization (90 degrees C/1 min), and their storage stability at 4 degrees C for 4 weeks were determined. It was found that pressurization and pasteurization were satisfactory eliminated the general microbes in Maoberry juice, also both processed juices exhibited a better microbiological stability throughout the refrigerated storage period. A significant change of pH in low pressure treated juice (400 MPa) during storage could be due primarily to the increase of general microbes. Both processing had no effect on the dynamic viscosity of Maoberry juice, but the reductions of the viscosity in all processed juices were observed after storage for 4 weeks. Considering the color parameters, the reddish (a*) of pressurized juices were similar to the fresh juice, suggesting that high pressure could preserve the anthocyanins (red-purple pigments) in the juice better than thermal treatment. The polyphenol oxidase (PPO) activity was completely destroyed after pasteurization, whilst this enzyme still remained in pressurized juices at 400 and 600 MPa up to 79% and 53% respectively. Upon the storage, all pressurized juices showed a gradually decrease in the residual PPO activity when the storage was extended. This study also displayed that the retentions of ascorbic acid, phenols and anthocyanins as well as antioxidant capacity (DHHP and FRAP assays) in pressurized juices were significantly higher than that the pasteurized juice during the entire storage. (C) All Rights Reserved