Effects of High Pressure on Vegetative Microorganisms

Increasing consumer demand for minimally processed, additive-free, shelf-stable products prompted food scientists to explore other physical preservation methods as alternatives to traditional heat treatments. Ultra high pressure is one of the most promising of these techniques. Ideally, the pressure treatment should result in microbiologically safe and stable foods over as wide a range of conditions as possible. Thus, there is a strong need for pressure treatments that inactivate not only vegetative cells but also bacterial spores. The application of high pressure as a sporicidal treatment is still in an exploratory state. However, pressure treatment has been known as a preservation technique for more than a century, since Hite (1899) demonstrated that microbial spoilage of milk could be delayed by the application of high pressure. Currently, a number of pressure-treated products are commercially available. Generally these are relatively acidic foods, such as fruit juices, which are pressure treated to reduce the number of vegetative bacteria, molds, and yeasts. Many other potential applications involving meat and dairy products are now being investigated.