Irradiation

Principle

Exposing food to ionizing radiation

Ionizing radiation or irradiation is used as a method to destroy enzymes and micro-organisms in food; kill mould; delay ripening of fruits and vegetables; inhibit sprouting in bulbs and tubers; remove insects from grain, cereal products, fresh and dried fruits, and vegetables; and destroy bacteria in fresh meats, all with minimal effect on the nutritive value of food.

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Irradiated foods are not radioactive

a. Radiant energy disappears from the food once it is removed from the source of ionizing radiation because the food itself never comes into direct contact with the radiation source.

b. There is no radiation hazard from consuming irradiated foods

　

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Type of radiation used for food preservation is ionizing radiation

a. Wavelengths of 2000 Angstroms (Å) (10^-10) or less

b. Includes gamma rays, x-rays, and electrons

1. Gamma rays: radiation emitted from the excited nucleus of radioactive elements, such as cobalt-60 and cesium-137

2. X-rays: produced by bombardment of heavy-metal targets with high-velocity electrons

3. Electrons: produced by linear accelerators

　

The three basic techniques for radiation processing; interactions of electrons, X rays, and gamma rays in the medium

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Effect on nutritional quality

• Nutritional losses resulting from irradiation are considerably less than with other food processing techniques

• The chemical reactions associated with food irradiation do, in fact, produce very small amounts of new compounds called radiolytic products

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Disadvantage

If irradiated food becomes contaminated, new pathogens have little competition and can multiply more rapidly. Therefore, strict sanitation and cooking standards, and limits on the amount of bacteria allowed in food, remain essential to ensure safe irradiated food.

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Commercially available irradiated foods must be clearly labeled

The international symbol used to label irradiated foods is called the radura

There are three components of the radura symbol

1. The solid circle represents the energy source

2. The clam shell figure represents the food

3. The five openings in the outer circle represent rays from the energy source

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Examples: Some fruit (peaches, strawberries, tomatoes ), mushrooms, vegetables and potatoes (prevents sprouting)

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