Pascalization

Pascalization, bridgmanization, high pressure processing (HPP) or high hydrostatic pressure (HHP) processing is a method of preserving and sterilizing food, in which a product is processed under very high pressure, leading to the inactivation of certain microorganisms and enzymes in the food. HPP has a limited effect on covalent bonds within the food product, thus maintaining both the sensory and nutritional aspects of the product. The technique was named after Blaise Pascal, a 17th century French scientist whose work included detailing the effects of pressure on fluids. During pascalization, more than 50,000 pounds per square inch (340 MPa, 3.4 kbar) may be applied for approximately fifteen minutes, leading to the inactivation of yeast, mold, vegetative bacteria, and some viruses and parasites. Pascalization is also known as bridgmanization, named for physicist Percy Williams Bridgman. Depending on temperature and pressure settings, HPP can achieve either pasteurization-equivalent log reduction or go further to achieve sterilization, which includes killing of endospores. Pasteurization-equivalent HPP can be done in chilled temperatures, while sterilization requires at least 90 °C (194 °F) under pressure. The pasteurization-equivalent is generally referred to as simply HHP (along other synonyms listed above), while the heated sterilization method is called HPT, for high pressure temperature. Synonyms for HPT include pressure-assisted thermal sterilization (PATS), pressure-enhanced sterilization (PES), high pressure thermal sterilization (HPTS), and high pressure high temperature (HPHT).