High pressure processing (HPP)
As currently used commercially, HPP is a non-thermal pasteurisation process in which a food is subjected to pressures in the region of 150 MPa to around 700 MPa (1500 to 7000 bar) and held at pressure for a given period of time. Pressure generation is through mechanical pressure exerted on the fluid and 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.
Newsletter items: HPP and clean label
Case study: Exploring the potential of high–pressure processing
R&D 226: High pressure sterilisation: temperature distribution studies in a laboratory scale high pressure vessel
R&D 233: A comparative study of high pressure sterilisation and conventional thermal sterilisation: quality effects in green beans and carrots
R&D 103: High pressure acidification: a feasibility study
Poster: Survival of microorganisms in High Pressure Processing (HPP) systems and the potential for leaker spoilage.
Bulletins: 25 and 31
Publications: HPP guideline for processing
HPP Linkedin pages -
Links to manufacturers – nc hiperbaric
CHIC FresherTech Co. LTD.