Download to read offline
More Related Content
Similar to FOOD IRRADIATION - INTRODUCTION, PRINCIPLE, INSTRUMENT
FOOD IRRADIATION - INTRODUCTION, PRINCIPLE, INSTRUMENT
- 1. FOOD IRRADIATION Sree NandanaS Food Science & Technology KUFOS
- 2. INTRODUCTION • Food Irradiation– Process of exposing food and food packaging to ionizing radiations without direct contact to the food product. • Ionizing radiation – γ rays, x rays or electron beams. • Improves food safety. • Extend product shelf life. • Reduce the risk of foodborne illness. • Delay or eliminate sprouting or ripening. • Control insects and invasive pests.
- 3. DOSE & DOSIMETRY •Radiation dose - Quantity of energy absorbed during exposure. • Earlier measured in rad (radiation absorbed dose). • Recently measured in Gray (Gy). • 1 Gray = 100 rad. • 1 Gy represents 1 J of energy absorbed per kilogram of irradiated product. • Different levels of dose are required to achieve desired results for the products. • Dosimetry is the science of measuring and calculating radiation doses.
- 4. PRINCIPLE • Destroy microorganismsby cold sterilization. • Cold sterilization - Killing of micro-organisms in foods with electromagnetic radiations without raising temperature. • Ionizing radiations ionize molecules on their path. • Ionizing ability – Ability of radiations to break chemical bonds to cause ionization when absorbed. • Cause several changes in the molecular structure of organic matter. • Cause ejection of an orbital electron from atoms/molecules due to high energy.
- 5. • Products ofionization may be electrically charged (ions) or neutral (free radicals). • Ionization radiation ionize molecules by creating positive and negative ions by transferring energy. • They dislodge electrons from atoms and molecules and convert them to electrically charged particles called ions. • Radicals are short lived (less than10ˉ sec) but can destroy bacterial cells. ⁵ • Cause direct or indirect effects on biological materials. • Direct effect - Chemical events occur due to energy deposition by the radiation on the target molecule.
- 6. • Indirect effects- Due to reactive free radicals formed such as hydroxyl radical, hydrogen radical, H2O2, and hydrogen. • In foods with high moisture content, water is ionized by radiations. • H2O2 - A strong oxidizing agent. A poison to the biological systems. • Hydroxyl radical - A strong oxidizing agent. Hydrogen radical - A strong reducing agent. • Radiolysis – secondary changes caused by ions & free radicals in an irradiated material. • Radiolysis cause the destruction of micro-organisms, insects and parasites .
- 7. INSTRUMENT • Irradiation equipmentconsists of:- 1. A high-energy isotope source to produce γ-rays, or 2. A machine source to produce a high-energy electron beam. • γ-radiation from Co-60 or Cs-137 used in most commercial plants. • Co-60 emits γ -rays at two wavelengths with energies of 1.17 MeV and 1.33 MeV. • Residence time of food determined by dose required and power output of source. • An isotope source cannot be switched off. • Shielded within a pool of water below the process area.
- 8. • Openings inthe shielding, for entry of products or personnel, must be carefully constructed to prevent leakage of radiation. • Co-60 has a half-life of 5.26 years and therefore requires the replacement of 12.3% of the activity each year to retain the rated output of the plant. • Machine sources are electron accelerators which consist of:- 1. A heated cathode to supply electrons. 2. An evacuated tube where electrons are accelerated by a high-voltage electrostatic field. • Either the electrons are used directly on the food, or a suitable target material is bombarded to produce X-rays.
- 9. 1. Can beswitched off. 2. Electron beams can be directed over the packaged food to ensure an even dose distribution. 3. Radiation contained within the processing area by use of thick concrete walls and lead shielding. 4. Not using radioactive materials eliminate the need for the disposal and management of spent isotopes. 5. Unlike isotope sources which decay over time, machine sources provide consistent performance. ADVANTAGES OF MACHINE SOURCES
- 11. • Radiation source(Cobalt) is shielded under water in an underground tank when not in use. • When the cobalt is in the water, people can safely enter the irradiation room. • Radiation shield (Concrete walls) prevent gamma rays from escaping into the environment. • Packaged food is loaded onto a conveyer belt for treatment. • Treatment is controlled by a control console by controlling the speed of the conveyer belt. • Fence keeps treated and untreated food separate.
- 12. Co-60, γ FACILITY •Radioactive material contained in two sealed, encapsulated stainless steel tubes called source pencils. • Placed in a rack and immersed in a water chamber underground when not in use. • Rack raised when irradiation takes place. • Gamma rays pass through the encapsulation and treat the food. ELECTRONIC BEAM FACILITY • Electron Beam Linear Accelerator concentrate and accelerate electrons to 99% of speed of light. • Produces rapid reactions in the product molecules. • Conveyer moves product under electron beam at a predetermined speed to obtain the desired dosage. • Product thickness depends on density and electron energy. X- RAY FACILITY • An electron beam accelerator targets electrons on a metal plate. • Some energy is absorbed and the rest is converted to X-rays. • X-rays can penetrate food boxes up to 15 inches thick or more. • Food can be processed in a shipping container. TYPES OF FACILITIES
- 13. NUTRITIONAL QUALITY • Irradiationis a cold process, hence no increase in temperature of the food. • Nutrient losses are less than other methods such as canning, drying, heat pasteurization. • Carbohydrates, proteins, and fats undergo little change during irradiation. • Four vitamins are highly sensitive to irradiation - B1 (Thiamine), C (ascorbic acid), A (retinol) and E (alpha-tocopherol). • Improves product recovery and higher juice yield in fruits. • Does not leave any chemical residues in foods.
- 14. APPLICATIONS • Phytosanitary insectdisinfection for grains, papayas, mangoes, avocados. • Sprouting inhibition for potatoes, onions etc. • Delaying of maturation, parasite disinfection. LOW DOSE APPLICATIONS (<1kGy) MEDIUM DOSE APPLICATIONS (1-10 kGy) • Shelf-life extension for chicken and pork, fish, seafood, strawberries, carrots, mushrooms, papayas.
- 15. • Control offood-borne pathogens for beef, fish, seafood, eggs. • Spice irradiation. HIGH DOSE APPLICATIONS (> 10 kGy) • Sterilization of foods. • Shelf-stable foods without refrigeration.
- 16. APPLICATIONS DOSE (kGy) Inhibitionof sprouting 0.03-0.12 Insect disinfestation 0.2-0.8 Parasite disinfestations 0.1-3.0 Shelf-life extension (Radurization) 0.5-3.0 Reduction of microbial population in dry food ingredients 3.0-20 Elimination of non-spore forming pathogenic bacteria (Radicidation) 1.5-7.0 Production of meat, poultry and fishery products shelf- stable at ambient temperature (Radappertization) 25-60
- 17. TYPES OF IRRADIATION RADURIZATION •Radurization is the process of pasteurization by the use of radiation. • It is primarily used to treat foods with high pH and water activity. • Organisms targeted are usually grain-negative psychrotrophs, the main spoilage organisms. • Meats and fish are the foods for which this process is mainly used. • It can also be used to target yeasts and molds in foods that are low in pH and low in water activity. • The treatment dose is approximately <1 Gy.
- 18. RADICIDATION • It isthe process of treating food product to destroy pathogenic organisms the product. • This process only kills vegetative cells and not spores. • The dose for radicidation ranges from 2.5 - 5.0 kGy. • Most vegetative cells are killed this dose. • Some strains of radiation-resistant organisms like Salmonella murium survive this treatment. • After radicidation, the product should be stored at or below 4°C to prevent any growth of spores from the Clostridium botulinum.
- 19. RADAPPERTIZATION • It refersto irradiation applied to pre-packaged, enzyme- inactivated foods to reduce the number and/or activity of microorganisms. • It is a process that is not recommended for most foods. • It involves treating the product to levels of radiation of approximately 30 - 40 kGy. • This high level of radiation kills vegetative cells and also destroys spores from organisms, such as Clostridium botulinum. • The process renders the food shelf stable without refrigeration. • Equivalent to commercial sterility of foods by canning.
- 20. ADVANTAGES • It involveslittle or no heating of the food. • There is negligible change to sensory characteristics. • Packaged and frozen foods may be treated. • Fresh foods may be preserved in a single operation. • There is no use of chemical preservatives. • Energy requirements are very low. • Processing is automatically controlled and has low operating costs. • It prevents food loss by controlling spoilage.
- 21. DISADVANTAGES • The processcould 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. • 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. • It causes loss of nutritional value.
- 22. CONCLUSION • Food irradiationis a safe and effective technology used to enhance food safety and quality. • It reduces risk of foodborne illnesses by eliminating harmful micro-organisms, and extends shelf life by delaying spoilage. • Some critics express concerns about potential nutritional changes and the long-term effects. • Research has shown that food irradiation is both safe and beneficial when properly regulated. • As consumers continue to seek safer, fresher, and longer-lasting food options, food irradiation presents a promising solution to meet these demands without compromising food quality. • Public awareness and continued research remain important for ensuring its responsible use in the food industry.