Alongside traditional processes for preserving food, namely drying, smoking and salting, the 20th century saw the introduction of innovative techniques such as irradiation, pascalisation or high pressure processing (HPP), microfiltration and biopreservation. These processes require cutting-edge technology and are mainly used in the food industry.
A wary approach to its use
The patent for the use of ionising radiation to kill bacteria in food was issued in 1905. International studies were conducted on this subject in the 1950s and in Switzerland from the mid-1960s. No other technique for preserving food has given rise to so much basic and applied research as the technique of irradiation. Foodstuffs which have been irradiated according to specified norms are not radioactive and pose no risk to human health. The World Health Organization’s position on this subject is unequivocal. The irradiation of herbs and spices has been generally authorised in Switzerland since 1st April 2008. The irradiation of foodstuffs remains subject to authorisation and irradiated products must be labelled as such.
Preserving using high-energy rays
Preservation by irradiation is also called ionisation, whereby food is exposed to gamma rays, X-rays or electron beams. Ionising radiation penetrates the foodstuff, including the packaging, and releases energy. This energy destroys bacteria and causes reactive particles to form, which react with the food components within a fraction of a second. This process inhibits germination, slows down decay, kills pathogenic microorganisms and destroys insects and their larvae. Following the use of irradiation, other innovative preserving techniques emerged during the 20th century, such as pascalisation or high pressure processing (HPP), microfiltration and biopreservation.
Pascalisation is where food products are subjected to very high pressure of up to 6000 bar, bearing in mind that 10 km below sea level the pressure is 1000 bar. This high-pressure processing is also called cold pasteurisation. It prolongs the shelf-life of food by causing a reduction in bacterial flora. It also slightly changes the colour and taste of food, but does not alter the vitamin content at all.
Microfiltration is a technique involving the physical separation of components. It uses filter membranes with pore sizes ranging from 0.1 to 10 micrometres in diameter and is used to destroy bacteria in liquids.
The biopreservation of food involves adding microorganisms to food, generally packaged in a protective atmosphere. The microorganisms have been selected for their ability to inhibit the growth of other undesirable microorganisms. This technique seems to be a good alternative to methods which use chemical food additives.
Japan, a forerunner in the use of high pressure
The use of high pressure in the food industry started in Japan at the end of the 20th century, with the packaging of acidic products such as fruit juice and jam. The Japanese then extended high pressure processing to meat and fish, rice cakes etc. Subsequently, other countries, including France, embraced this new technology. Products having undergone such treatment can be recognised by the pascalisation
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