What are the differences and similarities between irradiation and pasteurisation of food?

Ana Cardoso, Australia

Pasteurisation and irradiation are methods for preserving food. They both kill micro-organisms but they work different:

Pasteurization is the process of heating food for the purpose of killing harmful organisms such as bacteria, viruses, protozoa, moulds, and yeasts. The process was named after its inventor, French scientist Louis Pasteur. Unlike sterilization, pasteurization is not intended to kill all micro-organisms in the food. Instead, pasteurization aims to achieve a reduction in the number of viable organisms, reducing their number so they are unlikely to cause disease -assuming the pasteurized product is refrigerated and consumed before its expiration date.

Pasteurization is typically associated with milk. Milk simply labeled "pasteurized" means the milk was hold at a temperature of 72 degrees for at least 15 seconds.

Irradiation is a physical treatment of food with high-energy, ionising radiation. It can be used to prolong the shelf life of food products and/or to reduce health hazards associated with certain products due to the presence of pathogenic micro-organisms. The treatment may be applied for different purposes, such as:

• Prevention of germination and sprouting of potatoes, onions and garlic
• Disinfestation by killing or sterilising insects which infest grains, dried fruit, vegetables or nuts
• Retardation of ripening and ageing of fruit and vegetables
• Prolongation of the shelf life and prevention of food-borne diseases by reducing the number of viable micro-organisms in meat, poultry and seafood
• Reduction of micro-organisms in spices and herbs

In practice, the use of this technique is rather limited although it is authorised in many countries. Labelling laws differ from country to country. Irradiated foods may be labelled with a number of euphemistic terms used not to alarm consumers by such as cold pasteurization and electronically pasteurized.
http://europa.eu.int/comm/food/food/biosafety/irradiation/index_en.htm

Read this answer about UV-light and irradiation:
http://www.foodexperts.net/technology-production/index.php?action=showqa&id=173