Irradiation As A Means Of Preservation In The Food Industry

Project and Seminar Material for Food Science and Technology (FST)

Abstract

Food irradiation is a food preservation method which involves the process of exposing foodstuffs to a source of energy capable of stripping electrons from individual atoms in the targeted material (ionizing radiation). This method of food preservation can be referred to as a more advanced form of food preservation. Some school of thought criticize the use of irradiation for food preservation because of the negative impressions of the nuclear industry, and this has made irradiation one the most investigated forms of food preservation. Food irradiation has being endorsed by the World Health Organization (WHO), and is currently being used in over 40 countries and approximately 500,000 tons of food items are irradiated yearly all over the world. This work has highlighted some problems associated with the use of food irradiation technology in Nigeria, and has also proffered solutions that can help tackle the said problems. This work has also discussed the process of food irradiation, the recommended sources and the dose range required for effective irradiation of food products.

Chapter One

1.1 Introduction

Food Irradiation is the process of exposing food to ionizing radiation to disinfect, sanitize, sterilize, preserve food or to provide insect disinfestation. (wikipedia.org)

Food irradiation is sometimes referred to as cold pasteurization or electronic pasteurization to emphasize its similarity to the process of pasteurization. Like pasteurization of milk and pressure cooking of canned foods, treating food with ionizing radiation can kill bacteria and parasites that would otherwise cause food borne diseases. (wikipedia.org; www.cdc.gov)

By irradiating food, depending on the dose, some or all of the microbes, fungi, viruses or insects present are killed. This prolongs the life of the food in cases where microbial spoilage is the limiting factor in shelf life. Some foods (e.g. herbs and spices) are irradiated at such high doses (5kGy or more) that they show microbial counts reduced by several orders of magnitude. It has also been shown that irradiation can delay the ripening or sprouting of fruits and vegetables and replace the need for pesticides.

Studies have shown that when Irradiation is used as approved on foods:

Disease-causing germs are reduced or eliminated.
The food does not become radioactive
Dangerous substances do not appear in foods
The nutritional value of the food is essentially unchanged. (www.cdc.gov)

In the food industries, specific types of radiation treatments are used, they are Radurization, Radicidation, and Radappertization. However, in the actual process of irradiation, three different irradiation technologies are used namely; gamma irradiation, electron-beam irradiation and x-ray radiation. (www.cdc.gov)

The dose of irradiation is usually measured in a unit called the Gray, abbreviated (Gy). This is a measure of the amount of energy transferred to food, microbes or other substances being irradiated. To measure the amount of irradiation something is exposed to, photographic film is exposed to irradiation at the same time.

The killing effect of irradiation on microbes is measured in D-values. One D-value is the amount of irradiation to kill 90% of that organism. For example, it takes 0.3kGy to kill 90% of Escherichia Coli, so the D-value of E.coli is 0.3 kGy. (www.cdc.gov).

A distinctive logo has been developed for use on food packaging, in order to identify a product as irradiated. This symbol is called the “radura” and is used internationally to mean that the food in the package has been irradiated. (www.cdc.gov)

1.2 Food Irradiation Developments

There is a widening gap in the less developed countries (LDC’s) of Africa, Asia and Latin America between the growth rates of population and food production. Yet, in LDC’s over a quarter of the harvested food is lost due to wastage and spoilage. In Nigeria, very high losses of foods, especially highly perishable foods such as fish, fruits, vegetable and some dietary staples such as yam, maize, millet and sorghum occur in the time lag between harvest and consumption and during storage. There is, therefore, the need for greater utilization of the available appropriate technologies of food preservation in these countries (Aworh, 1986).

In the last three decades a new technology, food irradiation, has been developed which has the potential of reducing food losses in LDC’s (Aworh, 1986).

Research on Food irradiation dates back to the turn of the 20th century. The first US and British patents were issued for use of ionizing radiation to kill bacteria in foods in 1905. Food irradiation gained significant momentum in 1947 when researchers found that meat and other foods could be sterilized by high energy and the process was seen to have potential to preserve food for military troops in the field. To establish the safety and effectiveness of the irradiation process, the U.S. Army began a series of experiments with fruits, vegetables, dairy products, fish and meat in the early 1950’s. (www.ccr.uc davis.edu).

In 1958, Congress gave the FDA authority over the food irradiation process under the 1958 Food Additive Amendment to the Food, Drug and Cosmetic Act. The FDA has approved food irradiation process for wheat, potatoes, pork, spices, poultry, fruits, vegetables and red meat (www.ccr.uc davis.edu).

Food irradiation was recognised by the United Nations which established the Joint Expert Committee on Food Irradiation. Their first meeting was in 1964. The committee concluded in 1980 that “irradiation of foods up to the dose of 10kGy introduces no special nutritional or microbiological problems”. (www.ccr.uc davis.edu).

In 1999, the World Health Organisation determined the dose limitation at very high dose is palatability etc. Irradiation should be considered parallel to cooking in all aspects of safety. (www.ccr.uc davis.edu).

Tremendous progress has been made, in the past few decades, in the design and construction of safe radiation facilities and chances of radiation accidents are now very remote provided that personnel have been properly trained in the operation of radiation facilities (Aworh, 1986).

1.2 Statement of Problem

Food, being the most important and only substance that is universally consumed by all humans and animals to stay alive, need to be handled or safe guarded properly because contamination anywhere along the food chain can have far reaching effects and sometimes fatal consequences. Food borne illnesses is a burden in terms of incapacitating people, causing discomfort, cost of pain, grief and suffering, disruption to industry and commerce and strain on the health service

A great proportion of diseases can be attributed to contamination of food and drinking water. Globally, food contamination creates an enormous social and economic burden on communities and their health systems. Nigeria, diseases caused by major food pathogens are estimated to cost up to 35 billion naira annually in medical cost and lost productivity.

This research work seeks to analyze the practice of food irradiation as a means of food preservation in Nigeria. Consequences and prospects.

1.3 Objectives of Study

To assess food irradiation technology usage in Nigeria.
To identify the poroblems of food irradiation practice in noigeria
To identify the prospects of food irradiation.

1.4 Methodology

Materials and Methods

Food Material

In the study the variety of cobalt-60 and cesium-137 emit from the experimental orchards of El Menzah of the INRA, in 1998 were used. These food had not undergone any previous treatment for conservation. Food materials received in bulk lots were sorted out to eliminate the damaged food and divided into 10 Kg lots for different treatments.

Irradiation Treatment

In both the studies, fruits were irradiated to doses of 125, 250, 375 and 500 Gy along with unirradiated control. The choice of these doses was based on an earlier study during the agricultural campaign of 1997, which established the optimal dose ranges for this variety without affecting the fruit quality. The results of these studies using doses of 0, 250, 500, 750 and 1000 Gy showed evidence of a faster decomposition of fruits after three weeks of storage when irradiated to 750 and 1000 Gy, whereas samples irradiated to 250 and 500 Gy could be stored for 45 to 60 days.

Therefore, for the present study doses up to 500 Gy were employed. Following irradiation fruits were stored at ambient temperature and 10oC, and the control samples at 0oC.

Before irradiating the experimental samples, dose mapping was carried out to determine the dose distribution in samples. Different devices were used for irradiation of the samples in the study.

Chapter Five

Conclusions and Recommendation

5.1 Recommendations

If food irradiation technology is to gain widespread usage in Nigeria, then the problems highlighted in the previous chapter needs to be addressed. This section will attempt to proffer possible solutions to the problems highlighted in the previous chapter.

A. Lack of Adequate Equipments

The fact that Nigeria has just one functional irradiation facility is a setback. If Nigeria has to measure up with other developed countries as regards the use of irradiation technology for the preservation of food and other materials commercially, then she will need to begin setting up more irradiation facilities at strategic locations, so as to enhance easy accessibility from all parts of the country. To address the above issues properly, a system must be put in place that brings public and private sectors together for active interaction. A cue could be taken from the Food Corporation of India, which has played a significant role in transforming the Indian food economy. It operates through a countrywide network of institutions and infrastructures at zonal, regional and district level (Oyewole and Oloko, 2006). Active co-operation between the relevant government agencies and the private sector will in more ways than one hasten the creation or construction of more irradiation facilities at strategic geo-political zones and locations in the country, in order to make this technology accessible to potential users.

Once these structures are put in place, it will also go a long way to address the issue of transportation. Once GIFs are available at strategic geo-political zones and locations in the country, places where production is high, then the constraint of moving food produce over long distances will be considerably minimized.

B. Cost Arising From the Actual Service

There is also need for production incentives in terms of favorable pricing linked with efficient marketing facilities, if losses are to be reduced. In Nigeria, however, incentives are generally minimal or non-existent. There is no provision for cushioning farmers against periods of sharp price fluctuations. The issue of price assurance must be addressed so that the farmer can increase production to levels that will ensure stability of supplies to meet both normal and emergency requirements.

Also, the slight increase in price for irradiated food is insignificant considering the benefits the consumers get in terms of convenience, improved hygiene of the food, quantity and availability (Frenzen et al., 2000).

C. Lack of Adequate Sensitization

To solve the issue of inadequate sensitizations, there should be a platform for extension agents to actively disseminate information on improved storage techniques to farmers in the rural areas through use of mass media (e.g. radio/television) and farmers groups. Available sources of storage technologies should also be communicated to farmers by the zonal extension service.

Also, the use of some modern storage technologies requires specialized skills and technical know-how which farmers are lacking. Farmers should be trained on the use of these improved storage methods such as storage by irradiation. Institutions, the government and other organizations should arrange regular workshop training for farmers and those who operate agricultural machinery, in a bid to educate and familiarize them with this technology, and to encourage its adoption.

D. Transport System

Also necessary, is the Construction of Feeder Roads. These must be built to convey the large amounts of farm produce now wasting away in the fields because of lack of transport facilities. This problem can also be solved setting up more irradiation facilities at strategic locations, so as to enhance easy accessibility from the farms to the facility.

5.2 Conclusion

This report has attempted to discuss the prospects and problems associated with the use of food irradiation as a food preservation method in Nigeria. Food irradiation is a food preservation method which involves the process of exposing foodstuffs to a source of energy capable of stripping electrons from individual atoms in the targeted material (ionizing radiation) (Anon, 1991). This method of food preservation can be referred to as a more advanced form of food preservation. Some school of thought criticize the use of irradiation for food preservation because of the negative impressions of the nuclear industry, and this has made irradiation one the most investigated forms of food preservation. Food irradiation has being endorsed by the World Health Organisation (WHO), and is currently being used in over 40 countries and approximately 500,000 tons of food items are irradiated yearly all over the world.

The common sources of ionizing radiation recommended by the codex general standard for use in food irradiation include;

Gamma rays produced from the radioisotopes cobalt-60 (60Co) and celsium-137 (137Cs) Machine sources generating electron beams and x-rays.

Machine sources have the advantage that no radioactive substance is involved, and it can be switched off and on with the just the push of a button.

Though food irradiation brings about some chemical changes in food, these changes are not different from those that occur when food is exposed to other forms of food processing or probably when food is cooked. However based on hundreds of scientific tests, there is a broad agreement among scientists and health agencies that these changes do not pose a human health issue.

Food can be irradiated either in its prepackaged form or its packaged form depending on the type of food product. The food products are exposed to ionizing radiation over a particular period of time, to achieve the desired and recommended dose rate. This process is carried out in specially designed and shielded facilities so as to avoid incidences of environmental pollution.

In Nigeria, food irradiation has not gone beyond the experimental stages. But with the present efforts of some relevant government agencies such as the Small and Medium Enterprise Development Agency of Nigeria (SMEDAN) and Nigeria Atomic Energy Commission (NAEC), and also some promising research from various scholars in Nigeria, there is a promising indicator that this technology will soon reach its stage of commercialization in Nigeria.
The problem of population-food imbalance, caused by food wastage and spoilage is common to most developing nations of the world including Nigeria. One of the effective strategies that can be used in solving this problem is to reduce the amount of food lost in the post-harvest system. Several investigations by Nigerian scholars have confirmed that food irradiation technology will adequately help reduce spoilage and wastage of some basic food products in Nigeria.

The Nigerian government under the directive of the NAEC also shares the same view and as such have begun to put some structures in place so as to enable meaningful research work on the usefulness of this technology on Nigerian food products and to facilitate the smooth introduction of this technology in Nigeria. It is in this light that the NAEC created six nuclear research centers among which is the Nuclear Technology Centre (NTC), Sheda Science and Technology Complex, for research and development (Agedah, 2014), which houses a 340 kCi Co-60 Gamma Irradiation Facility (GIF). This facility is currently being utilized by various researchers in the country.

Despite all these efforts, there are still some critical issues that need to be addressed for the smooth introduction of this technology in Nigeria. These problems include; lack of adequate irradiation facilities, cost of procuring this service, cost of setting up more irradiation facilities, lack of adequate sensitization etcetera.
If irradiation is to gain widespread use in, then the highlighted problems would need to be adequately tackled.