Food Irradiation Preservation Methods PDF

Irradiation  Learning Outcomes At the end of this the theory of irradiation the equipment used section, you should have an understanding of Safety features Effect on food and required...

Irradiation  Learning Outcomes At the end of this the theory of irradiation the equipment used section, you should have an understanding of Safety features Effect on food and required packaging as a preservation method  Provide energy which destroys DNA in bacteria, parasites, insects, molds Gamma Rays from radioactive SOURCE What is material Cobalt 60 Cesium 137 Food Irradiation? Accelerated electron beams X-Rays  Irradiation Ionising radiation takes It is permitted in 38 the form of gamma -rays countries to preserve from isotopes or, foods by destruction of commercially to a lesser micro-organisms or extent, from X-rays and inhibition of biochemical electrons. changes.  When radiation strikes other material, it transfers energy this can cause HEATING, as with microwave cooking or, if there is enough energy, it can Ionizing knock electrons out of Radiation of the material bombarded, breaking the molecular structure - thus leaving ions (free radicals) hence the name - Ionizing Radiation --  Theory ▪ -rays and electrons are distinguished from other forms of radiation by their ionising ability (that is they are able to break chemical bonds when absorbed by materials). ▪ It is these reactions that cause the destruction of micro- organisms, insects and parasites during food irradiation. ▪ In foods that have a high moisture content, water is ionised by radiation. The main advantages of irradiation are as follows: there is little or no fresh foods may be heating of the food and preserved in a single packaged and frozen therefore negligible operation, and without foods may be treated change to sensory the use of chemical characteristics preservatives changes in nutritional value of foods are processing is energy requirements are comparable with other automatically controlled very low methods of food and has low operating preservation costs.  the process could be used to eliminate high bacterial loads to make otherwise unacceptable foods saleable if spoilage micro-organisms are destroyed but pathogenic bacteria are not, consumers will have no indication of the unwholesomeness of a food major disadvantages there will be a health hazard if toxin- producing bacteria are destroyed after they have contaminated the food with toxins the possible development of resistance to radiation in micro-organisms loss of nutritional value  Until recently, inadequate analytical procedures for detecting whether foods have been irradiated public resistance due to fears of induced radioactivity or other reasons connected to concerns over the nuclear industry. Irradiation ▪ These concerns have been addressed by the Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food (JECFI) who concluded that the maximum average dose of 10 kGy ‘presents no toxicological hazard and no special nutritional or microbiological problems in foods’  Use on finished, packaged product Fresh or frozen E-beam penetration 2 ½ - 3 inches Uses and Limitations May have to treat both sides Source is slower Need to change source in 5 years  Drawbacks ▪ Consumer perception ▪ is food safe to eat ▪ is the environment safe ▪ nutrient loss ▪ off flavor, aroma, color  Public Concerns?? ▪ Will new potentially harmful, chemical compounds be created in irradiated foods? ▪ Would nutrients be lost if foods were irradiated? ▪ Can unscrupulous processors use irradiation to conceal contamination of spoiled foods? ▪ Will workers or others be exposed to dangerous levels of radiation?  Current Uses of IR ▪ Medical/Pharmaceutical Products ▪ Airways and tubes ▪ Alcohol wipes ▪ Bandages ▪ Blood ▪ Contact Lenses ▪ Cotton Balls ▪ Dental anchors, burrs and sponges ▪ Drug mixing/dispensing systems Consumer ▪ Adhesive bandages ▪ Disposable nurser bottles Products ▪ Animal vaccines ▪ Food packaging... ▪ Baby bottle nipples ▪ ▪ Pacifiers Pet food ▪ Contact lens ▪ Tampons cleaning solutions ▪ Cosmetics ▪ Dairy and Juice containers  Current Food Applications ▪ Spices, Herbs, Dehydrated Vegetables and Seasoning Mixtures ▪ Strawberries ▪ Papayas ▪ Mangos ▪ Poultry ▪ Mushrooms  Terms to describe energy level ▪ Dose - amount of energy transferred ▪ rad - old unit ▪ gray (Gy) - new unit ❖ very large dose = 1 million rad = 10kGy ❖ or 1kGy = 100,000 rad ▪ 1 chest X-ray =.01 rad ▪ natural background = 0.1 rad/year Applications of food irradiation  Isotope irradiation plant: 1, irradiation chamber; 2, control room; 3, infeed conveyor; 4, outlet conveyor; 5, raw food store; 6, irradiated product store; 7, concrete shielding wall  Effect on Food Effect of irradiation on water-soluble vitamins in selected foods A comparison of vitamin contents of heat sterilised and irradiated (58 kGy at 25ºC) chicken meat Effect on packaging Effect on Food The process of irradiation produces an effect in food similar to pasteurisation. Irradiation is used to: inhibit sprouting vegetables; delay ripening of fruits; kill insects and other pests; kill the micro-organisms which cause food spoilage or food poisoning.  Learning Outcomes At the end of this the theory of irradiation The equipment used section, you should have an understanding of Safety features Effect on food as a required processing method