Food irradiation is the controlled process that is a physical treatment of food with high‐energy ionising radiation. The use of irradiation is limited in many countries. If irradiation is used, it must be an authorised activity in the country where it takes place. Irradiation is a process by the manufacturer that must be identified on the packaging and documentation accompanying the designated batch in line with legislative requirements in the country where the operation takes place and the countries to which the product may be exported.
49.1 Irradiation must present no health risk and must not be used as an alternative to good sanitary conditions in the food supply chain, or to replace the elements of good manufacturing practice (GMP) defined in this Guide. Irradiation may be used to prevent germination and sprouting of vegetables such as onions, garlic or potatoes, to slow down the ripening, ageing and senescence of fruit and vegetables, and to destroy pathogenic or spoilage bacteria, moulds, viruses or insects and by doing so prolong the shelf life of food and minimise the likelihood of foodborne illness and food poisoning. The foods and food ingredients authorised for irradiation in the European Union (EU) are identified in a given list (see https://ec.europa.eu/food/safety/biosafety/irradiation/legislation_en). The national authorisations that are deemed valid are identified by the EU as well as the standardised analytical methods for the detection of irradiated foods which have also been adopted by Codex Alimentarius.1 The EU List of Approved Premises for Irradiation was last updated in 2015.2
49.2 Directive 1999/2/EC – Irradiation of Food and Food Ingredients lays down general provisions and the rules governing approval and control of irradiation and changes the rules on the labelling of foodstuffs that have been treated with ionising radiation. Directive 1999/3/EC establishes an initial positive list of foodstuffs that can be treated and freely traded within the EC. Document 2002/840/EC identifies the list of approved facilities in third countries for the irradiation of food as amended by 2004/691/EC, 2007/802/EC and 2010/172/EC and Commission Implementing Decision 2012/277/EU.
49.3 In the United Kingdom (UK) The Food Irradiation (England) Regulations 20093 or its equivalent implementing EU Directive 1999/2/EC and 1999/3/EC, as amended by the Commission Decisions above, contains mandatory labelling requirements on irradiated food sold. The Food Irradiation (England) (Amendment) Regulations 2010 made further amendments to the legislation and updated the list of approved food irradiation facilities.4 The overall average dose calculation is defined in the Food Irradiation (England) Regulations 2009, but it should be noted that while the dose can be readily determined for homogenous products, it is more difficult in a heterogeneous product where particulate size or density varies. In some cases, the mean value of the average values of the minimum dose measured in the product (Dmin) and the maximum dose (Dmax) will be a good estimate of the overall average dose. In this instance, the overall average dose is (Dmax + Dmin)/2. The ratio of Dmax/Dmin (dose uniformity ratio) must not exceed 3 and the maximum absorbed dose must not exceed 150% of the overall average dose.
49.4 The following types of ionising radiation are allowed by UK legislation:
- gamma rays from the radionuclides cobalt‐60 or caesium‐137;
- X‐rays generated from machine sources at or below an energy level of 5 million electron‐volts (MeV); and
- electrons generated from machine sources at or below an energy level of 10 MeV.
49.5 The food is passed through a field of ionising energy and the ionising radiation passes through the food, generating large numbers of short‐lived free radicals. These can kill micro‐organisms, such as Salmonella, and inhibit the processes described in 49.1. At no time during the irradiation process does the food come into contact with the radiation source and, by using cobalt‐60 or electron beams up to 10 MeV, it is not possible to induce radioactivity in the food. The length of time the food is exposed to the ionising energy and the strength of the source determine the irradiation dose, measured in kilograys (kGy), the food receives.
49.6 In the UK, only foods that fall within the following classes can be considered for irradiation:
Maximum overall average dose in kilograys (kGy)5
Fruit (including fungi, tomatoes, rhubarb) 2 Vegetables (including pulses) 1 Cereals 1 Bulbs and tubers (potatoes, yams, onions, shallots, garlic) 0.2 Dried aromatic herbs, spices and vegetable seasonings 10 Fish and shellfish 3 Poultry 7
These categories of food can first be irradiated and then used as ingredients in other food products. A mixture of foods from the same class, for example a blend of herbs and spices, can be irradiated. A composite food product is not permitted for irradiation treatment unless minor ingredients (including additives) together comprise no more than 2% by weight, excluding any added water from the calculation.
Supplier approval of ingredients should pay particular attention to whether spices have been irradiated at source not only to ensure appropriate labelling of the finished product but also as part of raw material risk assessment. Salmonella contamination of foods has been linked to ingredients such as ground black pepper.
Facilities and Control of the Process
49.7 Irradiation treatment of foods must be carried out in facilities licensed and registered for this purpose by the appropriate authority. Irradiation procedures must be fully validated and records retained to demonstrate their efficacy and their compliance with legislation. Revalidation is required whenever the product, its geometry or the irradiation conditions are changed. This revalidation process must be formally recorded.
During the process, routine dose measurements are carried out in order to ensure that the dose limits are not exceeded. Measurements should be carried out by placing dosimeters at the positions of the maximum or minimum dose, or at a reference position. The dose at the reference position must be quantitatively linked to the maximum and minimum dose. The reference position should be located at a convenient point in or on the product, where dose variations are low.
Routine dose measurements must be carried out on each batch and at regular intervals during production. In cases where flowing, non‐packaged goods are irradiated, the locations of the minimum and maximum doses cannot be determined. In such a case, it is preferable to use random dosimeter sampling to ascertain the values of these dose extremes. Dose measurements should be carried out by using recognised dosimetry systems, and the measurements should be traceable to primary standards.
During irradiation, certain facility parameters must be controlled and continuously recorded. For radionuclide facilities, the parameters include product transport speed or time spent in the radiation zone and positive indication for the correct position of the source. For accelerator facilities, the parameters include product transport speed and energy level, electron current and scanner width of the facility.
49.8 The irradiation facility must be licensed for specific foods at specific doses (see 49.6).
49.9 A person seeking a licence to irradiate food should give the following details with the written application:
- the applicant’s name;
- the applicant’s address;
- the address of the facility at which the applicant proposes to irradiate food;
- details of any licence or registration under any other legislation that enables the applicant to use ionising radiation at the facility in circumstances where, but for that licence or registration, that use would be unlawful;
- a description of each food that the applicant proposes to irradiate which is sufficient to show that it falls within a permitted category of food;
- in respect of each food described pursuant to subparagraph (e):
- the purpose for which the applicant proposes to irradiate the food and how that would benefit consumers;
- the method by which the applicant will ensure that the food is in a suitably wholesome state before irradiation;
- the overall average dose, maximum dose and minimum dose of ionising radiation that the applicant proposes to apply to the food;
- the method (including instrumentation and frequency) by which the applicant proposes to measure any dose of ionising radiation and the dosimetry standard that the applicant proposes to use to calibrate the dose meters used to measure it;
- whether or not the applicant proposes to irradiate that description of food in packaging in contact with the food and, if so, the packaging that the applicant proposes to use; and
- whether or not the applicant proposes to apply temperature control to the food while irradiating it and, if so, the temperature at which the applicant proposes to keep the food during the application of temperature control.
49.10 The facilities must be designed to meet the requirements of safety, efficacy and good hygienic practices of food processing, in accordance with current statutory regulations in the UK and elsewhere and GMP. A list of licenced facilities is contained in Schedule 1 and Schedule 2 of the Food Irradiation (England) (Amendment) Regulations 2010.
49.11 Control of the process involves the food manufacturer and the operator of the irradiation facility (licence holder). Controls within the facility must include keeping records such as licence details, treatment and type of each food consignment, plus details of dose measurements. Additionally, each consignment must be accompanied throughout the processing chain by relevant documentation. Premises and records are open to inspection by the licensing authority. The licence holder is responsible for retaining records for a minimum of 5 years.
49.12 Incoming product must be kept physically separate from outgoing product.
Food Quality and Safety
49.13 The food before and after irradiation should comply with the provisions of the Codex Alimentarius Recommended International Code of Practice – General Principles of Food Hygiene and, where appropriate, with the Codex Recommended International Code of Hygienic Practice relative to the particular food.
49.14 Food intended for irradiation should be of a similar microbiological quality to that being processed by other means. For those foods irradiated to eliminate or reduce pathogenic organisms in the food, details of microbiological testing are required. EU Regulation No. 2073/2005 on microbiological criteria for foods (as amended by EU Regulation No. 1441/2007)6 ,7 complements EU food hygiene legislation already described and applies to all food businesses involved in the production and handling of food. The microbiological criteria outlined can be used to validate manufacturing, handling and distribution processes and/or verify the acceptability of foodstuffs at specific stages in the process.
49.15 In the UK, public health requirements affecting microbiological safety and nutritional adequacy of specific foods must be observed.
49.16 Irradiation must not be used to process foodstuffs that do not meet the above microbiological quality standards.
49.17 Documentation referring to microbiological quality should accompany the food consignment from the manufacturer to the irradiation plant.
Application of the Process
49.18 Irradiation should only be applied to food manufactured in accordance with GMP, and with a demonstrable need for the particular use of the process in terms of food hygiene or other technological benefit. The doses applied should be commensurate with the application and within the set limit for the overall average dose for the food. Food manufacturers should define the correct dose to be applied, which should be adhered to by the irradiation plant operator.
49.19 Temperature control during distribution, handling and irradiation processing should be similar to the control exerted on analogous but non‐irradiated foods. Irradiated food must be stored and transported with appropriate documentation that contains a statement to the effect that the food has been treated with ionising radiation.
49.20 Packaging materials should be of suitable quality and acceptable hygienic condition and be appropriate for the purpose. They should be able to withstand radiation in terms of their physical and sensory properties and in terms of migration of mobile components into the food. A full description of the materials is required. Packaging dimensions, particularly those of bulk packs, should take into consideration the nature of the irradiation source with respect to depth of penetration.
49.21 Food must not be re‐irradiated. However, the full dose needed for a specific technological purpose may be given in sequential fractionated doses.
49.22 Imports of irradiated foods into the UK are permitted only from countries that have been approved by the licensing authority. Lists of irradiation plants approved to supply specific irradiated foods and lists of countries approved to export specific irradiated food should be consulted. Appropriate documentation must accompany each consignment.
49.23 Foods irradiated for export should comply with the guidelines described in Chapter 54.
49.24 Where the importing country’s statutory requirements differ from the exporting country’s standards, it is the responsibility of the suppliers to determine that their irradiated raw material or product will comply with these.
49.25 In the UK, irradiated foods, whether prepackaged or not, must be labelled with the statement ‘irradiated’ or ‘treated with ionising radiation’. This labelling requirement includes foods sold in catering establishments. Any irradiated ingredient incorporated into a food product necessitates the use of the same labelling terms in the ingredients list (see relevant food labelling regulations).