Purpose: The objective of this research was to explore the potential application of high pressure processing (HPP) to reduce or eliminate inoculated Salmonella enterica and Listeria monocytogenes in fresh cantaloupe puree (CP). Effects of HPP on background microbial loads were also examined.
Methods: Freshly prepared CP containing no and 0.1% ascorbic acid (AA) was inoculated with a bacterial cocktail composed of three serotype mixture of S. enterica (S. Poona, S. Newport H1275 and S. Stanley H0558) and a mixture of three strains of L. monocytogenes (Scott A, 43256 and 51742) to a population of ca. 107 CFU/g. Inoculated CP (ca. 5 g) was placed in individual sterile stomacher bags, double sealed and double bagged. Samples were pressure treated at 300, 400 and 500 MPa at 8°C and 15°C (initial temperatures) for 5 min. Treated samples were stored at 4°C and subjected to various analyses.
Results: Data indicated increased inactivation of both Salmonella and Listeria with higher pressure. Log reduction (LR) for samples containing 0.1% AA at 300 MPa, 8°C was 3.4 ± 0.6 and 1.2 ± 0.15 log CFU/g for Salmonella and Listeria, respectively, which was significantly lower (P < 0.05) compared to LR values of 6.6 ± 0.4 and 6.2 ± 0.2 log CFU/g for Salmonella and Listeria, respectively, at 500 MPa, 8°C. Initial sample temperatures had minor influence on LR values. Listeria exhibited higher resistance to HPP than Salmonella.
Significance: Study highlighted a method to enhance the safety and quality of cantaloupe puree. Results from this work suggest efficacious treatment strategy for CP indicating 6 or higher log reduction for pathogens with minimal impact on quality.