Comparison of the Effects of Ultra-High Pressure and Thermal Processing on Quality Changes of Rosa roxburghii Juice during Storage

This study was undertaken to compare the effects of ultra-high pressure processing (UHP, 500 MPa/10 min) and traditional thermal sterilization (90 ℃/15 min) on microbial and physicochemical properties, color and active ingredients of Rosa roxburghii juice during storage at 4 ℃ for up to 30 days. The results showed that after UHP and heat treatments, the total number of bacterial colonies was reduced to below 1.0 (lg (CFU/mL)). At the end of storage, the total number of bacterial colonies in UHP- and heat-treated juice were 1.83 and 2.60 (lg (CFU/mL)), respectively. Both treatments significantly increased (P < 0.05) the L^* value of Rose roxburghii juice; the browning degree of Rose roxburghii juice after heat treatment was significantly higher than that after UHP treatment (P < 0.05), indicating that the color of Rose roxburghii juice could be maintained better after UHP treatment. During storage, the b^* value showed a downward trend. Compared with heat treatment, UHP treatment could better maintain the total phenol, vitamin C (VC) and superoxide dismutase (SOD) activity in Rose roxburghii juice. At the end of storage, the retention rates of total phenol, VC, SOD and antioxidant activity in Rose roxburghii juice treated with UHP were 93.32%, 52.80%, 64.49% and 93.96% compared to 81.68%, 28.35%, 41.65% and 93.30% with heat treatment, respectively. In conclusion, UHP treatment is advantageous over traditional heat treatment in maintaining the quality characteristics and antioxidant components of Rose roxburghii juice. Therefore, it can be used as a new processing technology for Rose roxburghii juice.