Food irradiation-an advanced food preservation technique

FOOD is a fundamental need of human since his creation. To preserve, save and enhance the shelf life of food was the oldest concept of human being. Currently, food preservation, food safety and food security have become more scientific and global concern. There are various agents that may cause spoilage of foods that include microbes, pathogens, insects, yeast/moulds, internal biochemical mechanism of foods, miss handling of foods after the harvest and during storage, packaging and transportation etc. Among all these, microbes and pathogens are the most widespread cause that not only spoil the foods but are also a source of causing serious diseases in humans. Food irradiation is an advanced technique of food preservation that has numerous advantages over conventional chemical preservation methods.

In many countries including Pakistan, about 25-30% of the harvested commodities are lost due to spoilage by microbes and by lack of fine handling protocols. It is noteworthy that in countries where growing population rate is very high, these post harvest losses are not affordable. It is extremely important to reduce the post harvest losses caused by infestation and contamination. This reduction approach in post harvest losses become more important for Pakistan because in hot and humid climate, the spoilage takes place at a very rapid rate and to preserve the food for even few days sometimes sufficient to save them from spoiling before they can be consumed.

Food preservation can be achieved by several techniques or combination of techniques. The most important are high temperature, use of low temperature, freezing, drying (removal of water), fermentation, canning, pasteurization and use of chemical preservatives. These days the chemical preservation is the most widely used food preservation technique. Various chemicals are being used to enhance shelf life, to put in flavor, to add color, to give body and for various other purposes. These chemicals are called “Food Additives” and they have many undesirable effects on the health of the consumer. The diseases associated with the consumption of these additives include cancer, diarrhea, allergies, brain damage, hyperactivity, asthma, diabetes, adrenal gland malfunction, chest pain, dizziness, high blood pressure, excessive weight gain, liver diseases, Aggressive and violent behaviors especially in children etc.

Food irradiation technology is one of the most effective methods to minimize the abysmal effects of chemical preservation. Food irradiation means to expose the raw foods to controlled dose of gamma radiations which kill microbes and pathogenic organisms without varying the nutritional worth of food itself. The DNA of the microorganism is damaged by energy released from the radiation. As a result, microbes are either killed or there replication ceases. The effectiveness of the irradiation also relies on the sensitivity of the microbe to irradiation, rate of DNA repair, and on the quantity of DNA in the target microbes. Food irradiation is the only technique of killing pathogens in raw and frozen food. It is also pertinent to mention that irradiation of food does not make it radioactive as the rays do not leave any residual effect on foods.

Irradiation is effective and safe to use. Many food borne diseases can be prevented through irradiation. The effects of irradiation on the food and on people consuming these foods have been studied extensively for more than 40 years. These studies concluded that through irradiation microorganisms that cause diseases are reduced or completely killed. Secondly, the nutritional value of the food is not changed and thirdly the foods do not become radioactive after the radiation is employed on it.

Health and safety authorities of more than 40 countries have approved the use of irradiation in various types of food (it includes spices, cereal grains, legumes, grain products, fruit and vegetable products and meat). By the use of irradiation we can save the people from the residual injurious effects of chemicals that are used to remove insects from dried fruit and grain, legumes, spices and other food stuffs.

Some examples of application of irradiation in food are to inhibit sprouting (in potato, onion, garlic), to kill insects and parasites (cereal grains, fresh and dried fruits) and to delay ripening (fresh fruits and vegetables). For the above mentioned purposes a low dose of up to 1 KGy is enough. To extend the shelf life and to kill pathogens in sea food, poultry, meat, a medium dose of 1-10 KGy is applied. And for the industrial sterilization and decontamination of spices, meat, seafood and poultry, a high dose (from 10-50 KGy) is recommended. Radiation is also applied on food packaging materials in order to sterilize them. Milk cartons in Netherlands are sterilized by irradiation to make cartons free from bacteria.

Although American astronauts have consumed irradiated foods in space since 1970`s. However, irradiated foods are not widely available yet. Patients with weak immune systems are sometimes recommended to take irradiated foods to reduce the risk of a fatal infection. It can be concluded that in coming years, nuclear technology application in the shape of irradiation can play a very key role for food safety, food security and in minimizing public health issues by combating infectious diseases.

The author is Principal Scientific Officer at Food Science and Product Development Institute, National Agricultural Research Centre, Islamabad. He can be reached at

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