Many objectives may be achieved by exposing a pumpable substance to high pressure. For example, high pressure processing may be used to render a desired physical change in a substance by pressurizing the substance to a selected pressure for a selected period of time. High pressure processing may be used to chemically or physically modify chemical or biological substances, including food products. High pressure may be used to improve the quality of existing products, and to generate new products.
In brief, pressure-processing may be achieved by loading a substance into a pressure vessel, where it is pressurized to a selected pressure for a selected amount of time, commonly referred to as the "dwell time," to achieve the desired physical change in the substance. The vessel is then depressurized, and the contents unloaded. The pressure vessel is then reloaded with a volume of unprocessed substance, and the process is repeated.
Although current systems produce desirable results, issues of product contamination can arise. Contamination is an important issue in certain applications, particularly those involving pressure-processing of food substances. Contamination may potentially come from the outside environment, or may potentially result from exposure of the pressure-processed product to the unprocessed substance.