Comparison of effects of ultra-high pressure and heat sterilization on qualities of freshly-squeezed pineapple juice

Sensory quality, nutrient components and physicochemical properties of pineapple juice were studied, based on achievement of commercial sterilization requirements by ultra-high pressure (UHP) treatment and heat treatment separately. The results showed that total number of bacteria declined with the increase of pressure (300-500 MPa) and arrived commercial asepsis at 400 MPa for 10min. Besides, the sterilization was at the same level by heat treatment (85℃ for 5 min); pH value, total acid, total sugar, soluble solid content of pineapple juice had no significant change in both UHP treatment and heat treatment (P>0.05); the system of juice was stable by UHP treatment; the color of juice by UHP was better than that of heat treatment, while the value of L*, a* and b* changed significantly (P<0.05) after UHP treatment; the retention of antitype ascorbic acid appeared to be 94.92%, which was much higher than that of the heat treatment; the results of quantitative descriptive analysis (QDA) showed that the pineapple juice after UHP treatment was more closer to control sample than that under heat treatment in color, flavor and taste. It is concluded that UHP treatment can effectively inactivate the microbe and maintain the flavor and quality of pineapple juice.