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Ionising radiation for food decontamination

Identification

Key words Gamma ray, X-ray, ionisation, DNA, decontamination, electron beam, ionising radiation, RNA
Latest version 2010/12/20
Completed by IRTA

How does it work?

Primary objective This technology is designed for decontamination of foodstuff and food products.
Working principle Ionising radiation occurs when one or more electrons are removed from the electronic orbital of the atom. It can be produced by three different techniques; gamma ray processing, high energy electron (called e-beam) and X-ray processing. When the radioactive source hits a material, the energy is absorbed by the inner shells of the atoms thus temporary modifying the electron arrangements. For living organisms, these modifications of molecular bonds induce an alteration of the microbial DNA structure and RNA synthesis. The final result is the death of the microbial cells.

Gamma rays are mainly produced by a source of radio-nuclides such as Cobalt 60 (60Co) with a half life of 5.27 years and Cesium 137 (Cs-137) with a half life of 30.19 years. In the industry, the majority of facilities uses the Cobalt 60 because of the higher energy delivery and because it is not soluble in water. Electron beams are produced by commercial electron accelerators with the advantage that they can be switched off. X-ray can be produced by an electron beam, when the electrons strike any material. If a target of tantalum or platinum is used, strong X-ray with an energy superior to 1 MeV can be produced.

Raw products as well as packaged products are placed in front of the irradiation source for a few minutes until the appropriate dose is reached. Due to biological hazard all product movements are automatic. In most countries a maximum dose level of 10 kGy applies, which corresponds to 10 kJ/kg. For sterilisation of special diet food a level of 50 kGy applies.

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Additional effects Besides inactivation of microorganisms, disinfestation and sprouting inhibition can be obtained. These applications are used for storage and export of crops and fruits.
Important process parameters pH, temperature
Important product parameters adsorbed dose (Grays -Gy), Sensitivity (D-value) of the microorganism (moulds and Gram-positive vegetative bacteria are more resistant than Gram-negative), fat content, salt content, additives.

What can it be used for?

Products Liquid or solid foods, also in a frozen state.

The list of products depends strongly on legislation and may vary from one country to another (see FAO in the Codex Alimentarius in 2003, European Parliament and of the Council, 1999a, 1999b). On a European level the irradiation of herbs and spices is allowed in all member countries.

Operations Decontamination, sterilization
Solutions for short comings Ionisation radiation has the advantage to be a non thermal decontamination technique and can be applied on package products or on whole food boxes. Thus reducing the impact of the technology to nutritional and sensorial qualities.

What can it NOT be used for?

Products Restriction is related with the legislation in vigour (Official journal of EU 2009/C 283/02) and with the approval of national safety agency. For a defined product, irradiation treatment can induce sensorial, and colour modification as well as lipid oxidation, generation of free radicals and 2-alkylcyclobutanes.
Operations Irradiation technology requires a high investment and maintenance cost. Facilities have to be designed in order to ensure the control of the radiological hazard for the personal and the environment. Operations is restricted to limited facilities and facilities must be approved by national authorities to process food products. EU commission has a list of facilities approved available on the web site of the commission: http://ec.europa.eu/food/food/biosafety/irradiation/index_en.htm.

In Europe, equipments are limited to 10 MeV for an e-beam equipment and 5 MeV for an X-ray one.

Other limitations Products treated with this technology must be labelled with different words and symbols depending of the country. The Radura Logo is one of them:
2 1 1 radura logo ionising radiation 1.JPG
2 1 1 radura logo ionising radiation 2.JPG
Risks or hazards The risks are associated with the ionising energy for the operators of the irradiated plant and the biological shield to protect them and the environment. The ionised radiation does not convert the atoms of food product in radio-nuclides.

Implementation

Maturity The technology is mature and used in some European countries (19 facilities in 12 countries). In addition it is used in the US, India and other countries and approved in 60 countries worldwide.
Modularity /Implementation A special facility has to be designed with specific conditions related with a Radioactive plant. This facility has a high cost of several millions Euro.
Consumer aspects In Europe most of the consumers have rejected the technology.
Legal aspects
  • Framework Directive (1999/2/EC)
  • Implementing Directive (1999/3/EC)
  • European Commission Communication 2001 (Official Journal, C 241, 6-11)
  • ISO 14470:2011—Food irradiation: Requirements for the development, validation, and routine control of the process of irradiation using ionizing radiation for the treatment of food
Environmental aspects Ionised energy has to be confined in the ionised chambers treatment in order to avoid the presence of ionised energy in the environment. Special concrete walls and lead walls have to be set up in order to comply with this.

Further Information

Institutes Institute of Applied Radiation Chemistry, Institute of Nuclear Chemistry and Technology, Texas A&M University
Companies Sterigene, Bioster, Gamma-Service, Ionisos, Aragogamma, Synergy Health, BGS Beta-Gamma-Service
References 1. Ahn, D. U., Nam, K. C., Du, M. & Jo, C. (2001). Volatile production in irradiated normal, pale soft exudative (PSE) and dark firm dry (DFD) pork under different packaging and storage conditions. Meat Science, 57, 419-426

2. Ahn, D., Lee, E. J. & Mendonca, A. (2006b). Meat decontamination by irradiation. In L. M. L. Nollet & F. Toldra (Eds.), Advances Technologies for Meat Processing (pp. 483 pages). NY: Taylor & Francis Group.

3. Aymerich T., Picouet P.A., Monfort J.M. (2008), Decontamination technologies for meat products, Meat Science 78 , 114–129

4. Borsa, J. (2006). Introduction: food irradiation in moving on. In C. H. Sommers & X. Fan (Eds.), Food Irradiation Research and Technology (pp. 317 pages). USA: Blackwell Publishing Professional Ames.

5. European Parliament and of the Council. (1999a). Directive 1999/3/EC on the establishment of a community list of foods and food ingredients treated with ionising radiation. Official Journal, L 66, 24-25

6. European Parliament and of the Council. (1999b). Directive 1999/2/EC on the approximation of the laws of the member state concerning foods and food ingredients treated with ionising radiation. Official Journal, L 66, 16-22

7. European Commission. (2001). Communication from the Commission on foods and food ingredients authorized for treatment with ionising radiation in the Community (Text with EEA relevance). Official Journal, C 241, 6-11

8. Sommers, C., Fan, X., Niemira, B. & Rajkowski, K. (2004). Irradiation of ready-to-eat foods at USADA. Radiation Physics and Chemistry, 71, 509-512

9. Sommers, C. & Boyd, G. (2006). Variations in the radiation sensitivity of foodborne pathogens associated with complex ready-to-eat food products. Radiation Physics and Chemistry, 75, 773-778



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Created by Hte irta on 9 February 2012, at 08:55