Effects of High Hydrostatic Pressure Treatment on Microbe and Quality of Mixed Apple Puree

In this study,apple,kiwi and carrot were used as raw materials to prepare apple puree. Sensory evaluation was carried out on different proportions of samples to determine the best ratio,the effects of high hydrostatic pressure(HHP)processing parameters(treatment pressure,holding time)on sample biology and quality were studied.According to sensory evaluation,the optimal ratio of apple:kiwi:carrot was 6:2:1,and the high hydrostatic pressure sterilization parameters were determined by screening as 400 MPa/2 min and 500 MPa/2 min. According to the results,there was no significant difference in soluble solids,dietary fiber,total carotenoids and β-carotene content between the HHP samples and heat treatment samples(P>0.05). The color of the HHP samples were better and the HHP samples had higher ascorbic acid content and antioxidant capacity.The ascorbic acid content was between 0.75 and 0.83 mg/100 g,while the heat treatment samples were only 0.55 mg/100 g. At the same time,the HHP samples' viscosity were higher and average surface area were smaller. The high hydrostatic pressure treatment samples had weaker passivation ability to polyphenol oxidase(PPO)and pectin methylesterase(PME)than heat treatment.Residual enzyme activity of the HHP samples were 56.70%~65.54% and 82.08%~86.91%,the heat treatment samples were 38.04% and 81.89%.Therefore,the high hydrostatic pressure treatment can better ensure the physical and chemical characteristics and nutritional quality of mixed apple puree,but the ability to passivate enzymes is not strong.