Abstract: In this study, the effect of high pressure carbon dioxide (HPCD) on the microbial indexes and flavor of fresh watermelon juice was investigated. The total bacteria, mold and yeast count, and typical flavor compounds of watermelon juice after treated with HPCD for 60 min at 30 MPa were analyzed and compared to those of samples thermally treated at 95 ℃ for 1 min. Microbial analysis was carried out on watermelon juice during 30 days of storage at 4 ℃.The results showed that better sterilization results were achieved by the thermal treatment than the HPCD treatment. The microbial indexes of watermelon juice samples sterilized by the different treatment methods were in line with the requirement of the national standard Hygienic Standard for Fruit and Vegetable Juice and could meet consumer demands for fresh watermelon juice within the shelf life. The HPCD treatment had little impact on typical flavor compounds of watermelon juice and little changes were observed during storage. In general, HPCD treatment is more suitable than heat treatment for fresh watermelon juice production.

Key words: high pressure carbon dioxide (HPCD), watermelon juice, sterilization, flavor