High pressure processing, as currently used commercially, is a non-thermal pasteurisation process in which a food is
subjected to pressures of about 150 to 700 MPa (1500 to 7000 bar) for a given period of time. Pressure generation is mechanical, through a fluid
(water), which is consequently transmitted to the product. There is usually a volume reduction of around 12% (resulting from the compressibility
of water) as pressure is applied, this is reversed when the pressure is released. A small temperature rise is observed as a result of compression
that is typically around 3-4°C per 100 MPa of applied pressure but can vary depending on the food product.
The high pressures used for HPP can inactivate vegetative microorganisms, yeasts, moulds and certain enzymes. The extent
of microbiological inactivation is affected by many factors including; the intrinsic properties of the food such as its pH, water activity, fat
content, protein content, mineral and sugar content, bacterial growth phase and the pressure, temperature and time combinations that are applied.
The, essentially, non-thermal nature of high-pressure pasteurisation makes it an excellent process for preserving the
´fresh–like´ characteristics of foods. Unfortunately, bacterial spores are very resistant to commercially achievable pressures. As a result,
products that are currently on the market tend to be chilled and/or contain additional preservation hurdles such as pH, water activity control
or other combinations of factors that have been demonstrated to prevent the growth of psychrotophic strains of Clostridium botulinum.
We have an EPSI High pressure system with a 700 ml capacity on site for lab scale validation and product suitability
trials. We can partner with contract processors should clients wish to explore full scale production trials.