Preservation of Food through Radiation

Many advanced methods of preserving foods have been developed, but all have limitations. With the possible exception of freezing and refrigeration, most processes limit  the usefulness of a food or alter its characteristics undesirably. Under radiation processing, the food is subjected to radiation by exposing it to a source of ionising radiation.  IRRADIATION PROCESSING is Exposing food to gamma rays, x-rays or electrons to improve shelf life and safety.This ionising radiation usually is in the form of gamma rays from a source of cobalt-60 or from a non-radio active source like electron beam generated from electricity. The irradiation process involves passing of food through a radiation field allowing the food to absorb desired radiation energy. The food itself never comes in contact with the radioactive material.

The technologies used are:

·        Gamma rays have been used routinely for more than 30 years to sterilize medical, dental, and household products. They are also used for radiation treatment of cancer.

·        Electron beams (E-beams) are propelled out of an electron gun that is a larger version of the part of a TV tube that propels electrons into the TV screen, making it light up.

·        X-ray irradiation. The X-ray machine is a more powerful version of the machines used in many hospitals and dental offices to take X-ray pictures. X-rays can pass through thick foods. They require heavy shielding for safety.

The irradiation process has been approved by the Food and Agriculture Organisation (FAO), the World Health Organisation (WHO), the International Atomic Energy Agency (IAEA) and the Codex Alimentarius Commission. About 100 countries have approved the process for application in more than 100 items of food. India first approved them in 1994. All packaging materials currently used in food industry are suitable for irradiation. Many packaging materials including laminated plastic films with aluminium foil used for packaging of foods are routinely sterilized by irradiation. Thermoluminescence measurement and electron spin resonance spectroscopy can be used for detecting radiation processed spices and meat containing bone tissue.

Radiation processed food cannot be recognized by sight, smell, taste or touch. Irradiation is a cold process and can be used to pasteurize and sterilize foods without causing changes in freshness and texture of food unlike heat. Unlike chemical fumigants, irradiation does not leave any harmful toxic residues in food and is more effective. It is efficient and can be used to treat prepacked commodities.

IRRADIATION PROCESSING improve shelf life and safety. .Irradiation breaks chemical bonds killing microorganisms, insects.no heat generated. used in canning industry , equivalent to pasteurization of milk. In comparison with heat or chemical treatment, irradiation is considered a more effective and appropriate technology to destroy food borne pathogens.

Irradiation produces very little chemical changes in food. None of the changes known to occur have been found to be harmful. The radiolytic products and free radicals produced are identical to those present in foods subjected to treatment such as cooking, canning etc.

BY RATNIKA SRIVASTAVA