Techniques and Equipment used in HPP

High-pressure technology of foods in similar to conventional heat processing, using two main types of industrial equipment. One is a batch system for processing packed foods.  A typical high pressure system consists of a pressure vessel and pressure generating device. Food packages are loaded into the vessel and to top closed. The pressure medium, usually water containing a small amount of soluble oil, is pumped into the vessel from the bottom. Once the desired pressure can be maintained without further need for energy input. The process is isostatic, so pressure is transmitted rapidly and uniformly throughout both the pressure medium and the food with little or no heating. It is equal from all sides so there is no ‘squashing’ effect and product is not affected. Pressure in the range of 300, 700 MPa are used for foods (500 MPa is equivalent to 20 family cars bearing down on an area the size of postage stamp). These pressures, maintained for approximately 15 minutes, can cause more than a 10,000 fold reduction in numbers of food poisoning bacteria such as Salmonella, Compylobacter and Listeria in milk and poultry meat.