Preservation by irradiation

IRRADIATION

1. PRESERVATION OF FOODS BY IRRADIATION: PRINCIPLES AND METHOD OF RADIATION TOPICS: Introduction Irradiation Mode of action Radiation in food preservation Electron beams , x-rays , gamma rays Units of irradiation Terminology for food treatment Radurization , Radiciation , Radappertization Benefits of food irradiation

2. Introduction: Food irradiation is a physiological process of subjecting food to shortwave radiation ,sterilization , disinfestation etc irradiation is considered as appropriate technology to destroy food borne pathogens as compared to heat or chemical preservation

3. IRRADIATION: Food irradiation is low temperature sterilizing technique as in this case sterilization can be effected at room temperature .Foods are exposed to high energy gamma rays or fast moving electrons Cobalt-60 or cesium-137 electrons producing machines are the principle sources of ionizing radiations used for food irradiation . It is also known as cold pasteurization as it kills harmful bacteria without heat.

4. MODE OF ACTION: The food is exposed to ionising radiation either from gamma rays or a high-energy electron beam or powerful x-rays . Gamma rays and x-rays are a form of radiation that shares some characteristics with microwave ,but with much higher energy and penetration. The rays pass through the food just like microwaves in a microwave oven ,but the food doesn’t heat up to any significant extent .electron beams and x-rays are produced using electricity ,which can be switched off or on ,and they do not require radioactive material.

5. RADIATION IN FOOD PRESERVATION: Ionizing radiation is the radiation with enough energy to remove electrons from atoms and molecules and convert them into charged particles called ions Three types of ionizing radiations are approved to be used for food irradiation 1.electron beams generated from the machine sources operate at maximum energy of 10MeV 2.X-Rays from machine sources operate at a max energy of 5MeV 3.Gamma rays are emitted from Co-60 or Ce-137 with respective energies of 1.33 and 0.67MeV.

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7. UNITS OF IRRADIATION: Radiation dose is the quantity of radiation energy absorbed by the food as it passes through radiation field for processing .The Gray ( Gy ) is the unit used to measure radiation 1Gy=100rad (radiations absorbed dose) 1KGy=100Gy According to good manufacturing practices (GMP’s) at any dose above 10KGy is also safe for consumption

8. TERMINOLOGY FOR RADIATION TREATMENT IN FOODS: RADURIZATION: Radurization process involves irradiation applied to obtain a substantial reduction in the number of spoilage organisms ,there by extending the shelf life of food 3-4 fold .It is applied at dosage of 0.5-10 kg.

9. . RADICIATION : Radiciation aims at reducing considerable number of nonspore forming pathogenic microorganisms and parasites . It is applied at dosage of 3.0-10KGy and improved the hygenic quality of food and reduces the risk of exposure to pathogens

10. . RADAPPERTIZATION : It also refers to irradiation applied to prepackaged enzyme inactivated foods to reduce the number and activity of microorganisms . for Ex-12D reduction in C.botulinum spores .it is applied at dosage of 25-60KGy.The process renders the food shelf stable without refregeration .

11. Benefits of food by irradiation Extended shelf life of products Less food spoilage Reduced risk of food borne diseases caused by microorganisms such as campylobacter , salmonella , e.coli and Listeria . Less need of pesticides Less need for some additives ,such as preservatives and antioxidants Lower risk of importing or exporting insect pests hidden inside the food products. Reduced need for toxic chemical treatments such as those used to kill bacteria found in some spices. Reduced sprouting in potatoes , onions and herbs

12. EFFECTS OF IRRADIATION ON FOOD: Some foods such as dairy foods and eggs cant be irradiated because it changes in flavour or texture Fruits ,vegetables , grain foods , spices and meat can be irradiated Irradiation causes minimal changes to the chemical composition of the nutrients ,however it can alter the nutrient composition of the food because it reduces the level of some of the B- group vitamins This loss is similar to those that occur when food is cooked or preserved in more traditional and accepted ways ,such as canning or blanching .

13. REFERENCE: https://www.betterhealth.vic.gov.au