Developments in high-pressure food processing

This chapter reports the developments made in the processing of foods using high pressure which over the past two decades. Consumers these days generally expect the food to be of a high quality, minimally processed, natural, additive-free, high in nutritional value as well as safe to eat. High Pressure processing is an alternative to thermal processing which can destroy harmful microorganisms rendering the food safe to eat. As a way of minimally processing food, it has the potential to preserve the quality of foods in many cases and even be responsible for producing new textures and properties. The effect of high pressure on the molecular structure of food proteins is to change their functional properties in surprising and often useful ways. A pressure of ten thousand times greater than atmospheric is capable of coagulating the albumin of egg without the use of heat. The purpose of using high pressure instead of heat is to preserve and even improve food quality in terms of taste, flavour, texture and colour. The molecular structure of many food components including sugars, oils, vitamins, lipids and pigments are able to resist the effects of high pressures. Pressure is capable of affecting only the weaker bonds and forces sufficient to alter the delicate molecular structures, as in the case of proteins. There have been some excellent examples worldwide of commercially applying high pressure in the processing of fruits, fish and shellfish, meat and dairy products. Research continues to understand fully the remarkable effects of high pressure on the constituents of food. In general, this has been in the areas of food safety with the destruction of micro-organisms, the activation and deactivation of enzymes; the functional properties of foods components to form foams, gels and emulsions; thermodynamics with the control of phase change. The most important of these has been to establish the sterilisation properties of high pressure food processing. Many harmful microorganisms differ significantly in their ability to withstand pressure while bacteria, yeasts and moulds are readily killed with spores being only inactivated by pressure after germination.