Hydrostatic High Pressure versus Thermal Pasteurization on Strawberry Puree: Microbiological and Color Analysis

The objective of this research was to examine the effect of hydrostatic high pressure (HHP) treatment on the stability of strawberry (Fragaria xananassa) puree in comparison to conventional pasteurization. Shelf-life and color were measured. The puree was packaged in 200 g flexible vacuum pouches. These packages are suitable for hydrostatic high pressure treatment. Two processing conditions were applied on industrial hydrostatic high pressure equipment: 400 MPa/3 min and 600 MPa/3 min. In order to compare the results to the standard process, pasteurization treatment was applied by full water immersion 85 degrees C/10 min. The samples were stored 30 days at 5 degrees C. The purees (not treated and treated by HHP and pasteurization) were analyzed 24 h after the treatment and after 30 days storage conditions to test the effect of the process. Tritratable acidity, pH, degrees Brix, microbial count and instrumental color were measured on fresh puree. These characteristics correspond to a standard product. The results show that HHP processed strawberry puree achieve a microbial reduction in order to have an interesting shelf-life (at least 1 month), and the red color is better preserved than the pasteurized puree and it is maintained during storage conditions.