Food Sterilization by Combining High Pressure and Thermal Energy

High pressure processing (HPP) is an industrially tested technology that offers a more natural, environmentally friendly alternative for pasteurization or shelf life extension of a wide range of food products (Welti-Chanes et al., 2005). Commercial high pressure, low temperature methods achieve inactivation of vegetative microorganisms by subjecting vacuum-sealed food in flexible packaging to treatment at hydrostatic pressures of 600 MPa (or less) and initial temperatures lower than 40°C for one to fifteen min depending upon the product application. The use of lower temperatures has allowed better retention of sensory attributes characteristic of “fresh” or “just prepared,” as well as food nutritional components (Cano and de Ancos, 2005). As a result, HPP has become a post packaging technology convenient for foods whose quality would otherwise be altered by heat pasteurization. Among many advantages, HPP can add significant value to low-cost or heatsensitive raw materials and other prepared foods. Furthermore, similar quality levels can be reached when processing large volumes or larger samples. Different from heat penetration, hydrostatic pressurization allows “instant” pressure transmission in fluids and semisolids within the pressure vessel, thereby achieving reduced product damage from lower temperatures. Moreover, HPP can add significant shelf life to an existing refrigerated product (Hjelmqwist, 2005). In fact, it has the potential to deliver chemicalor additive-free products with minimum impact on shelf life. Like any other food preservation processes, HPP is product specific, making shelf life extension dependent on food composition, the presence of enzymes, and on the actual bacterial species/strains present in a given food factory. Another use of HPP is in texture modification of foods with high protein content. Tenderized meats and modified dairy or egg-based ingredients of varied functionality are some examples of the benefits observed in texture modification (Montero and Gómez-Guillén, 2005; Guamis et al., 2005). The US Food and Drug Administration (FDA) and Department of Agriculture (USDA) have approved HPP as a post package pasteurization technology for