Food Irradiation Technologies

Concepts, Applications and Outcomes

Isabel C F R Ferreira, Amilcar L Antonio, Sandra Cabo Verde, Isabel C F R Ferreira, Amilcar L Antonio, Sandra Cabo Verde

• Editorial: Royal Society of Chemistry
• Año: 2017
• ISBN:
  9781788013925
• Edición: 1
• Categoría: Technology & Engineering
• Categoría: Food Science

Food preservation by irradiation is gaining recognition as a technology that is more environmentally benign than other current processes such as post-harvest chemical fumigation, it has less impact on thermally sensitive compounds than thermal decontamination technologies such as hot water or steam, and the technology is more accessible and cheaper. As the technical and economic feasibility, as well as the level of consumer acceptance, have increased its use has been growing fast. International organizations including the Food and Agriculture Organization of the United Nations (FAO), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) have coordinated and worked with others to develop norms and review the safety and efficacy of irradiated foods. Commended in the Foreword by Carl Blackburn, Food Irradiation Specialist, Joint FAO / IAEA Division of Nuclear Techniques in Food and Agriculture, this book makes a strong case for the use of this overwhelmingly safe food processing technique.

This comprehensive book is a useful reference for food technologists, analytical chemists and food processing professionals, covering all aspects of gamma, electron beam and X-ray food irradiation, its impact on food matrices and microorganisms, legislation and market aspects. It is the first book to cover control and structural analysis in food irradiation and, being written by leading experts in the field, addresses the current global best practices. It contains updated information about the commercial application of food irradiation technology, especially regarding the type of radiation based on food classes and covers dosimetry, radiation chemistry, food decontamination, food quarantine, food processing and food sterilization.

CHAPTER 1

Introduction

AMILCAR L. ANTONIO^a, SANDRA CABO VERDE^b AND ISABEL C. F. R. FERREIRA^a

^a Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 1172, 5300-253 Bragança, Portugal

^b Centro de Ciências e Tecnologias Nucleares, C2TN. Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 ao km 139, 72695-066 Bobadela LRS, Portugal

*Email: [email protected]

1.1 Almost the Beginning

For newcomers, food irradiation is a promising innovative food processing technology. However, those that have spent their lives working in this field since its first industrial use, around the 1950s, may consider that everything has already been done. In fact, the application of ionizing radiation for food preservation started immediately after its discovery. In 1895, W. R. Röntgen observed the existence of non-visible radiation, as disclosed by the famous picture of the first radiography of his wife's hand, where her bones and wedding ring could be discerned. The following year, H. Becquerel discovered the radioactivity of atoms, and the first patents on the use of ionizing radiation for food preservation were claimed in 1905.

Experiments with ionizing radiation have continued until the present day. Its use at industrial scale proliferated after the 1960s. In the US, ionizing radiation was first applied to develop sterile meat products to substitute canned and frozen military rations.

US astronauts have been using irradiated food since 1972. Also in 1972, the Japanese government allowed the irradiation of potatoes for sprout inhibition. With the progress of the technology, certain countries started to authorize its use at higher doses and application to other food items, contributing to the marketing of this technology (see Chapter 17).

Gamma rays, accelerated electrons (e-beam), and X-rays have been successfully tested for food processing, insect disinfestation (see Chapter 9), microbial decontamination (see Chapter 10), or to extend the shelf life of food (see Chapter 12). Their use is regulated (see Chapter 2), with all three types of irradiation processing (see Chapters 3 and 4) having enough energy to ionize atoms and break molecules without interfering with the nucleus, consequently not inducing radioactivity in food, the main concern of non-informed consumers (see Chapters 17 and 20).

In parallel, several materials have been tested in order to irradiate packed food (see Chapter 8), one of the main advantages of this technology, contributing to guarantee that a product meets the high standards of safety and quality, which, together with irradiation processing, is an essential tool to prevent food outbreaks with invaluable costs for the industry and, sometimes, also in terms of human lives (see Chapter 10). The industrial use of irradiation for food processing also follows a strict protocol under the qualification and certification of irradiation facilities (see Chapter 19).

1.2 Opening Frontiers

Due to public misconceptions about ionizing radiation and the strong uproar of anti-science movements, some countries have reversed or halted the progress in this area, as is the case with the European Union (see Chapter 2).¹ In the EU, a white list of irradiated products was established, with only one type of products in the list, spices and dried herbs. However, some countries have their own list, authorized by the EU, allowing the irradiation of several food products, such as vegetables, fish, or meat (see Chapters 2 and 20). Currently, its potential contribution to food processing is not fully exploited to reduce or eliminate the use of chemicals for postharvest food processing, which could be a driven force for the technology, so as to reduce the obvious adverse effects of some chemicals on the environment and humans. In addition, irradiation could be a feasible alternative for postharvest processing, such as hot water or steam treatments, with less impact on the food properties.

Although there are several qualified and certified gamma and e-beam irradiation facilities for food irradiation processing (see Chapters 2 and 19), some technical limitations still exist. Not all food products can be processed by this technology, as high doses would be needed to achieve the desired effect, potentially compromising the quality and shelf life of the product. Namely, foods with high fat content may be oxidized and doses above 5 kGy may also change certain organoleptic properties of fruits (see Chapter 11).

1.3 Still in Progress

Ionizing radiation applications for food preservation are more than a century old and its industrial use has been around for more than half a century. However, the interaction of ionizing radiation (gamma, e-beam, and X-rays) with natural matrices is a complex phenomenon, not as easily interpreted as the interaction with inorganic and single molecule materials, depending also on the irradiation conditions (dose rate, product temperature, and moisture content) (see Chapter 11).

The food product type (fruit, vegetable, fish, or meat), size (physical dimensions), state (solid or liquid), temperature (ambient or frozen), and irradiation conditions (dose rate or modified atmosphere) can be optimized to minimize the irradiation effects and improve its application for the desired purpose. These parameters, along with new trends in packaging materials (see Chapter 8), are the object of current research, maintaining the scientific community alive and working in this field so as to validate processes and study their effect on several natural matrices and under different irradiation conditions and technologies. This research is also contributing to maintaining the focus on the safety of this promising technology (see Chapter 16), albeit underused and still not fully accepted due to ignorance and/or misconceptions, as discussed above.

1.4 Has Everything Been Already Done?

The dose ranges for a variety of purposes are more or less well established: for sprout inhibition, less than 0.5 kGy; for insect disinfestation, up to 0.5 kGy; for shelf-life extension, 1 to 2 kGy; for microbial decontamination, up to 5 kGy; and for food sterilization, more than 5 kGy. With such food processes already under control by several methods (see Chapters 13, 14, and 15) and the technological applications so well defined, has everything been done?

In fact, this is not the case. As discussed in the previous section, the interaction of ionizing radiation with natural products is multifactorial, where some molecules may protect others from ionizing radiation effects, requiring case-by-case studies. The referred dose ranges should not be assumed to be universal for all food products. Even at low doses, such as those recommended for fresh fruit or vegetable preservation (about 1 or 2 kGy), certain adverse effects have been observed, such as organoleptic changes, compromising the use of this technology in such particular cases. Its combination with other technologies or processes could overcome these side effects, allowing its application for food preservation (see Chapter 12).

1.5 What Next?

To fully understand the impact of ionizing radiation in products where radiosensitive molecules are present, the combination with molecules able to protect the former from radiation effects and to increase the extractability of natural compounds with added value is still an open field. Not only the interaction of radiation with natural matrices needs to be studied, but also the technology for food irradiation is continually under development to make it more economically feasible (see Chapter 18). There is also a current tendency to test X-ray processing, limited in some countries to energies below 5 MeV, with ongoing research aimed at extending its use to higher energies (7.5 MeV), as authorized in the US but not in the EU. Recently, in 2015, the IAEA started a Collaborative Research Project (CRP) involving 13 countries with the objective of developing new technological solutions and simultaneously validating their application for different food items.

There is still room to continue research in this field, namely to optimize the irradiation conditions using the output of reliable dosimetry systems (see Chapter 5), to assess other beam energies to lower the cost of the processes, and to use mobile systems that may be applied in close proximity to the food production station (see Chapters 3 and 4).

Let's go through the book, chapter by chapter, contributing to the comprehension and recognition of such a global technology, able to foster and/or open new markets to guarantee the safety and quality of food.

¹ The European Union has broken recently this silence. EU Directive 1999/2/EC is currently under public discussion, with the objective to revise it (October 2017).

CHAPTER 2

International Standards and Regulation on Food Irradiation

IGNACIO CARREÑO

FratiniVergano – European Lawyers, Rue de Haerne 42, B-1040 Bruxelles, Belgium

Email: [email protected]

2.1 International Standardisation and Regulation on Food Irradiation

Food irradiation has been addressed in international standards recognised by the World Trade Organization's (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (the SPS Agreement), in particular in the Food and Agriculture Organisation of the United Nations (FAO) and the World Health Organisation (WHO) Codex Alimentarius Standard for irradiated food and in standards of the International Plant Protection Convention (IPPC). National legislation on food irradiation is, however, not always in line with those international standards. This chapter analyses different legal frameworks on food irradiation and argues that current regulatory approaches, which (inter alia) authorise irradiation of certain predefined product categories and set upper dose limits, do not appear to be in line with the approach used under the relevant internationally recognised standards, which focus on the technological purpose of the treatment, the minimum absorbed dose to achieve it, and the maximum absorbed dose. In conclusion, scientifically unjustified trade barriers for irradiated foods may arise.

2.2 International Standards on Food Irradiation

A number of international standards have been established regarding food irradiation. Article 3.1 of the WTO SPS Agreement encourages WTO Members to use international standards, guidelines and recommendations of the Codex Alimentarius Commission related to food safety, the IPPC related to plant protection and quarantine, and the International Office of Epizootics (OIE) related to animal health and quarantine, where they exist.

This section looks at the relevant international standards for irradiated food, namely the relevant Codex Standard and standards of the IPPC. Organisations like the International Standardisation Organisation (ISO) have also developed standards on irradiation.¹

2.2.1 Codex Alimentarius Standard

The Codex Alimentarius is the food standard-setting body of the FAO and WHO. Based on the findings of the Joint Expert Committee on Food Irradiation (JECFI), composed of members of the FAO, the International Atomic Energy Agency (IAEA) and the WHO, the WHO published in 1981 a document titled “Wholesomeness of Irradiated Foods”.² The document concluded that no further toxicological or nutritional research is needed on foods irradiated up to an overall dose of 10 kilogray (kGy). The Codex General Standard for Irradiated Foods No. 106-1983 adopted by the Codex Alimentarius Commission endorsed the JECFI's statement that: “The irradiation of foods up to an overall average dose of 10 kGy introduces no special nutritional or microbiological problems”. The publication of this standard had a profound influence on further international developments and formed the basis of legislation in many countries. The aim of the Codex Alimentarius is not to promote food irradiation; however, it has developed standards and a code of practice to effectively apply irradiation technology to improve food safety, together with guidance on the labelling of irradiated foods. It is left to governments to determine their own approach to the use of food irradiation.³

In 1997, in response to the technological need for average doses higher than 10 kGy to ensure that certain food items, particularly meat and poultry, are rendered consistently free of pathogens, the FAO/WHO/IAEA Study Group on High-Dose Irradiation assessed the safety and nutritional adequacy of food irradiated at doses above 10 kGy. On the basis of the extensive scientific evidence reviewed, the Study Group concluded in 1999 that food irradiated at any dose appropriate to achieve the intended technological objective is both safe to consume and nutritionally adequate. It was further concluded that no upper dose limit needs be imposed, and that irradiated foods are deemed wholesome throughout the technologically useful dose range below and above 10 kGy.⁴ The guiding principles for determining the wholesomeness of irradiated foods were such that foods are deemed safe if they pose no toxicological or microbiological hazards and adequate for consumption if they pose no special nutritional problems.⁵

On the basis of this conclusion, and in consideration that the previous Codex Standard stated that the overall average dose absorbed should not exceed 10 kGy, the Codex Committee on Food Additives and Contaminants (CCFAC) reached a compromise and agreed to remove the 10 kGy limitation by defining a more practically applicable statement on dose limitation, under clause 2.2 of Standard No. 106-1983: “For the irradiation of any food, the minimum absorbed dose should be sufficient to achieve the technological purpose and the maximum absorbed dose should be less than that which would compromise consumer safety, wholesomeness, or would adversely affect structural integrity, functional properties, or sensory attributes. The maximu...