Food irradiation

Food irradiation, sometimes called cold pasteurization or food ionization, is a treatment that can be given to certain foods using ionizing radiation, generally high-energy electrons or electromagnetic waves produced by radioactive elements. (X or gamma radiation). The process involves exposing food to controlled amounts of that radiation to achieve certain objectives.

The process is usually used to prevent the reproduction of microorganisms such as bacteria and fungi that cause food spoilage, changing their molecular structure and preventing their proliferation or some diseases caused by pathogenic bacteria. It can also reduce the speed of ripening or regrowth of certain fruits and vegetables by modifying or altering the physiological processes of their tissues without major alterations in their nutritional or organoleptic or physical properties.

Food irradiation is permitted in more than 60 countries, and about 500,000 metric tons of food are processed worldwide each year. Regulations on which foods can be irradiated vary greatly from country to country. In some countries such as Germany and Austria, only dried herbs, spices and seasonings can be processed with irradiation, and only at a specific dose, while in Brazil all foods are allowed at any dose.

Description of the radioactive process

The types of radiation used to process food are: gamma radiation, X-rays and accelerated electrons. These types of radiation are also called ionizing radiation and are accepted by international organizations such as the FAO, the WHO and the IAEA.

The gamma radiation-emitting radioisotopes normally used for food processing are cobalt 60 (⁶⁰Co) and cesium 137 (¹³⁷Cs).

The electron accelerators used have a maximum energy of 10 MeV and the X-ray equipment a maximum energy of 5 MeV. These energy levels are too low to induce radioactivity in materials, including food.

To treat food, it is exposed to a radioactive source for a certain period of time to achieve the desired dose. Radiation can be emitted by a radioactive substance or by x-ray and electron accelerators. Special precautions are taken to ensure that food never comes into contact with radioactive substances and that staff and the environment are protected from radiation exposure. Irradiation treatments are usually classified by dose (high, medium and low). Food irradiation is sometimes called "cold pasteurization" or "electronic pasteurization" because by ionizing the food it is not heated to high temperatures during the process, and the effect is similar to that of heat pasteurization. The term "cold pasteurization" It is controversial because it can be used to hide the fact that the food has been irradiated. Pasteurization and irradiation are fundamentally different processes.

Applications of food irradiation

Food irradiation offers several benefits to the food industry and consumers. From a practical point of view, the following classifications can be proposed:

Depending on the dose applied

The applications of this process can be grouped into three categories, depending on the doses applied to foods, such as:

Low dose irradiation

It is considered Low dose irradiation when a dose of up to 1 kGy is applied. It produces sprout inhibition, fruit disinfestation and inactivation of parasites and pests.

Medium dose irradiation

It is considered Medium dose irradiation when a dose of between 1 and 10 kGy is applied. It produces a reduction in the content of harmful microorganisms and pathogens, reducing the possibility of food-borne illnesses due to bacterial contamination...

Large dose irradiation

It is considered Irradiation at large doses when doses greater than 10 kGy are applied. It achieves a reduction in the content of microorganisms up to sterility.

According to the objectives

The applications of food irradiation, grouped by their objectives, can be classified as:

Reduction of pathogenic microorganisms

Among which can be mentioned: Escherichia coli O157:H7, Salmonella, Campylobacter jejuni, Listeria monocytogenes and Vibrio spp., known pathogens that are associated with meat, fresh produce, water and seafood..

Decontamination of spices, herbs and vegetable seasonings

These are frequently contaminated with microorganisms due to the environmental and processing conditions in which they are produced, which is why they require irradiation to reduce their bacterial count and make them viable for human consumption. Furthermore, the irradiation process allows these products to retain their original aromas and flavors.

Shelf life extension

Applicable to fruits, vegetables, beef, chicken, fish and seafood. Its shelf life can be considerably prolonged with a combined treatment of low-dose irradiation and refrigeration, without altering its flavor or texture. This effect has also become relevant in products with a short life or that must be transported over long distances.

Quarantine treatment of fresh fruits and vegetables

Citrus fruits, mangoes and papayas. It prevents infection by fruit flies such as the Mediterranean, Eastern, Mexican or Caribbean fruit flies, in areas that are considered free of these pests and allows international trade in these products without the risk of their proliferation.

Inhibition of sprouting in tubers and bulbs

By using irradiation, a constant supply of these products can be maintained and must be stored for several months. This process can be applied to potatoes, garlic, onions, ginger and chestnuts, among others, and leaves no residue, allowing it to be stored at temperatures between 10 and 15°C.

Countries where it applies

Several countries, including Bangladesh, Uruguay, China, Hungary, Japan, Korea and Thailand, commercially irradiate one or more foods, such as grain, potatoes, spices, dried fish, onions, garlic, etc., to control their losses.

In countries such as Belgium, France and the Netherlands, considerable quantities of frozen seafood and frog legs, as well as some dry feed ingredients, are irradiated to control bacterial contamination.

In several countries, including the United States, Argentina, Belgium, Brazil, Canada, China, Denmark, Finland, France, Holland, Hungary, Indonesia, Israel, Mexico, Norway, Korea, the United Kingdom and South Africa, some spices are irradiated, instead of being fumigated. The volume of dried spices and vegetable seasonings that are treated by radiation has increased significantly worldwide, reaching 60,000 tons in 1997. In the United States alone, 30,000 tons of these products were irradiated in 1997, compared to 4,500 tons in 1993.

History

Food irradiation is gaining greater attention over traditional methods of food processing and preservation. Although some people and institutions believe it is a new technology, research on this process dates back to the beginning of the 20th century, where the first patents for the use of ionizing radiation to kill bacteria in foods in the United States and Great Britain were granted in 1905.

Currently, health and radiation protection authorities in more than 40 countries have approved irradiation for around 60 different products, from spices, grain, boneless chicken and beef to fruits and vegetables.

In August 1999, there were approximately 60 facilities for food irradiation, being used in 30 countries on a commercial level. There are also several facilities under construction or in plans.

The decision of many countries to approve the irradiation of foods has been influenced by the adoption of a global standard on irradiated foods in 1983, by the Codex Alimentarius Commission, a body formed by the FAO (Organization of the Food and Agriculture of the United Nations) and the WHO (World Health Organization). The objective of this Commission is to recommend standards for food and its processing to protect the health of consumers and facilitate the practice of free trade in food.

Regulation

The general standard of the Codex Alimentarius is based on the research of an international committee of experts on food irradiation of FAO, WHO and the International Atomic Energy Agency (IAEA) and concludes that irradiation of any food up to a total average dose of 10 kGy does not present toxicological risks and does not require any additional testing, since it does not introduce special microbiological or nutritional problems.

However, in September 1977, another group of scientists from these same organizations was formed to evaluate the quality of foods irradiated with doses greater than 10 kGy, concluding that there is no scientific evidence to limit the dose. supplied to food at that value. This dose value of 10 kGy recommended by that Commission is equivalent to the heat energy required to increase the temperature of water by 2.4 °C, which is why food irradiation is called cold pasteurization.

Motivation

Interest in food irradiation has increased due to food losses worldwide, caused by infection, contamination and degradation during transportation from production centers to consumption centers. Also, the concern about diseases caused by foods contaminated by bacteria and the growing international trade in food products, which must comply with very strict quality and quarantine standards.

Food irradiation has been shown to offer benefits when integrated into an established system of safe food handling and distribution.

In addition, some regulations on the use of fumigants to control insects and bacteria in food are becoming increasingly stricter, even being banned, mainly because they leave some dangerous residues in food and damage the ozone layer. Therefore, irradiation is an alternative to protect food against damage caused by insects and as a treatment for fresh products.

The FAO estimates that food losses after being harvested worldwide are 25%, due to insects, bacteria and rodents. Using food irradiation as the only conservation technique will not solve all these problems but it can play a relevant role in reducing them, as well as reducing dependence on some fumigants.

In the United States, although the number of illnesses caused by contaminated food is not known precisely, it was estimated in 1994 that cases could have been between 6.5 and 33 million and that deaths caused by this problem could reach 9,000. people annually.

The United States Department of Agriculture (USDA) estimated that illnesses caused by the bacteria E. coli O157:H7 due to consumption of undercooked beef resulted in productivity losses and medical expenses of between 200 and 440 million dollars annually.

In developing countries, diseases caused by parasites such as Taenia solium and Trichinella spiralis constitute a serious health problem and, together with diseases due to contamination of food by bacteria, result in hundreds of millions of cases per year.

Trade

The exchange of food products is the main factor in regional and international trade and continues to grow. The lack of capacity of some countries to meet public health standards is the main barrier to this exchange, for example, not all countries allow the import of fruits treated with chemicals. On the other hand, some countries with large import capacity, such as the United States and Japan, have prohibited the use of certain fumigants or the import of products treated with them, since they have been considered dangerous to the health of their consumers.

In 1996, USDA reported that it would allow the importation of fresh fruits and vegetables treated with radiation against fruit flies. The problem is greater for developing countries whose economies are largely based on agricultural production and the profits generated from its export. Food irradiation offers these countries an alternative.

Recently, this authorization was extended to fresh products, such as Iceberg lettuce and spinach, which may be treated with radiation to reduce their content of pathogenic bacteria up to a dose of 4 kGy.

Every year hundreds of thousands of tons of food products are irradiated around the world. However, this amount is small compared to the total volumes of food that are processed and only some of these irradiated food products enter international trade.

One factor influencing how quickly food irradiation is being adopted is the public's understanding and acceptance of this process. Contrary to initial estimates, it has been shown that when irradiated foods are offered to consumers, they end up purchasing them due to their satisfaction with the quality and safety of these products.

Public perception and impact

Irradiation has been approved by the FDA for more than 50 years, but the most important area of its use has been the irradiation of fruits and vegetables for human consumption. In the early 2000s in the United States, irradiation was most popular in commercial food stores, but due to lack of consumer demand it is no longer common. The low demand for irradiated foods, added to a reduction in product deterioration between the producer and the consumer, reducing the risk of diseases, meant that producers did not currently include irradiation processes.

Negative consumer perception of foods treated with irradiation over other processes is widespread, although some industry studies indicate that the number of consumers concerned about the safety of irradiated foods has decreased in the last 10 years. at levels comparable to those of people concerned about preservatives and food additives.

Health risks

Irradiation treatments consist of subjecting food to doses of ionizing radiation, but this treatment destroys or degrades the DNA or proteins of pathogenic bacteria.

Irradiation appears to be safe for food, in the sense that it does not cause toxic alterations in its compounds. Peculiar byproducts do occur, but they have not been shown to cause harmful effects on our health. 2-alkyl-cyclobutanone, a byproduct derived from a fatty acid, was suspected of causing cancer-causing cell mutations, but research leads us to think otherwise.

Food irradiation can result in nutrient loss, for example, vitamin E levels can be reduced by 25% after irradiation and vitamin C by 5-10%. This is compounded by the longer storage times of irradiated foods and by the loss of nutrients during cooking. which can result in the food that the consumer finally consumes containing little more than "empty calories". This is potentially detrimental to the short- and long-term health of consumers, particularly for sectors of society that are no longer obtaining adequate nutrition.

When foods are exposed to high doses of ionizing radiation, the chemical composition and nutritional content of the food can change. Radiolytic byproducts often form in irradiated foods. Very few of these chemicals have been adequately studied for toxicity. One of these chemicals - 2-DCB - can cause DNA damage in rat colon cells at high doses.

Food irradiation does not inactivate dangerous toxins that have already been produced by bacteria before irradiation. In some cases, such as C. botulinum, it is the toxin produced by the bacteria, rather than the bacteria itself, that poses a health hazard. The extension of the EU list of foods permitted for irradiation could mean that in the future a significant part of consumers' diet will consist of irradiated foods. The long-term health impacts of this are unknown. Much more research is required before exposing populations. to such a diet.

Irradiation of products such as mechanically recovered chicken meat, organ meats and egg whites could mislead consumers into thinking they are safer. Therefore, there is a risk that consumers will not take the necessary measures to avoid cross-contamination. The risk of recontamination of food after irradiation is very serious since almost sterile food is an ideal medium for the very rapid growth of reintroduced bacteria. Therefore, irradiated foods must be handled even more carefully in homes and restaurants.

Irradiation can cause mutations in bacteria and viruses leading to potentially resistant strains.

Deceiving consumers

Irradiating fruits and vegetables to extend their shelf life can mislead consumers by making "old" look "fresh". The older the fruits and vegetables, the lower their nutritional value, not to mention the effects of aging on their tastes and flavors. Consumers can be dangerously misled because irradiation also inevitably kills bacteria that produce warning odors that indicate the food is 'spoiling.'

Irradiation of some products, such as dried fruits and cereal flakes or germs, often considered healthy foods (e.g. muesli), could lead consumers to wrongly perceive them as inherently contaminated types of foods.

Misuse of technology

Food irradiation can and has been used to mask poor hygiene practices in food production. With irradiation, contamination can be sterilized. This reduces the incentive to clean up sloppy food processing operations: the industry has a "quick fix" as an alternative to dealing with the sources of the problem The consumer has the right to expect clean food, but irradiation can lead to increased production of food contaminated with dirt - 'clean' dirt.

Irradiation can be used to maintain or even worsen poor standards of animal husbandry. Overcrowding of animals during breeding and before slaughter, as well as the use of cheap but inappropriate feed, contribute to the contamination of animal products such as meat, poultry and eggs. Cleaning these products at the end of the production line removes the incentive to improve animal welfare.

There have been violations of existing labeling legislation in European countries, with the sale of unlabeled irradiated foods. Recently, a UK government screening survey found this was happening again and found that almost half of the dietary supplements sampled were illegally irradiated and unlabelled (see press). In these circumstances, consumers' right to choice is violated. Relaxing irradiation standards could make this situation worse.

If successful, continued industry efforts in the US to replace the term 'irradiation' on the labels of irradiated foods with terms such as 'cold pasteurization' could serve to confuse and deceive consumers .

Worker safety

Workers are at risk of accidental exposure to dangerous levels of radiation, particularly in irradiation plants that use radioactive sources. Using irradiation to sterilize meat at the end of the production line allows slaughter lines to operate at dangerously high speeds, as the increased contamination that occurs during high-speed butchering of carcasses can "clean" at the end of the line. This increases the risk of accidents and deaths by forcing meat packers to work faster than ever.

Socioeconomic costs

Food irradiation is not a low-cost method. Irradiation plants are expensive and could help large multinationals eliminate smaller, local producers. Requirements to improve safety measures at all facilities containing radioactive materials are likely to increase costs for irradiation plants, leading to increased prices for irradiated foods. Irradiation supports further globalization of food production and supply, threatening local farmers and food processors.

Security risks

It has been reported that numerous unrecovered losses and thefts of radioactive materials occur each year. Recent events have raised concerns about the possibility of terrorists obtaining these materials for use in 'dirty bombs'. A dirty bomb uses conventional explosives to disperse radioactive material. Such an attack could cause radiation contamination across several city blocks, but probably no radiation deaths, due to the low doses as the material disperses. Still, such an attack could spread panic and have significant economic impacts and would require lengthy cleanup operations, even though these materials are fairly easily detected.

Environmental impacts

Accidents at radioactive irradiation plants have already caused radioactive spills and contamination of surrounding land and water resources, and this could happen again.

Construction of more irradiation plants could require greater transportation of radioactive materials, which carries risks of accidents and radioactive leaks over a wider area.

Irradiation allows food to be transported over long distances, leading to increased air pollution and greenhouse gas emissions that contribute to global warming