Introduction

The preservation of food is an ancient practice. Man used fire, sun-drying, salting and fermentation to keep his food longer. Today, sophisticated techniques of dehydration, freezing, heat and chemical treatments are established and accepted. Food irradiation is a relatively new revolutionary process with essentially the same objectives as those of the traditional methods of food preservation i.e., extending shelf-life and reducing the incidence of food-borne disease. Obviously, not all methods of preservation are applicable to all foods. Heat treatment, for example, cannot be used to preserve "fresh fruit." Other factors, e.g., cost, complexity, packaging and transportation must be considered in the choice of an appropriate method. Radiation-preservation is intended not to replace but to compliment the existing more conventional methods. It provides a remarkable technological versatility with far reaching implications to the important issues of world hunger, health and disease, and political unrest.

The irradiation treatment involves exposure of the food, under controlled conditions, to high speed electrons or x-rays from machine sources or to radiant energy from gamma rays. The amount of energy absorbed (dose) has been usually measured in rads (1 rad = 100 ergs absorbed per gram of matter). The rad is, however, superseded by the Gray (Gy) in the International System of Units (1 Gy = 1 joule/Kg = 100 rad). Chemical change resulting from radiation can be expressed in terms of the amounts of substrate change or new products formed. The G-value is used to express the number of molecules formed or destroyed per 100 electron volts (ev) of energy absorbed.

Although extensive research over several decades has provided ample evidence for the efficacy and the safety of this process, its widespread acceptance has been hampered by concerns based on emotions, misconceptions and erroneous association with the issues of nuclear reactors, nuclear weapons and radioactivity. It is hoped that the forces of education, public forums and media communications, can join in overcoming this problem. This article is an effort to provide a brief account of the various aspects involved in this new process.

2. ADVANTAGES

The irradiation treatment is a "cold" process because there is at most only a few degrees temperature rise in foods from the radiation energy absorbed, even at the higher doses used for sterilization. Consequently, radiation treatment causes minimal changes in appearance and provides good nutrition retention. It leaves no chemical residue and thus can replace chemical fumigation and reduce the need for chemical additives. It allows the treatment of products of a wide range of sizes and shapes, e.g., a truckload of produce, large carcasses, thin slices of meat. Food irradiated in flexible packages can be more easily stored and/or transported.

3. APPLICATIONS

As mentioned above, the two major objectives of food irradiation are elimination of pathogenic microorganisms and extension of shelf life. In addition, food irradiation has been effective in a variety of other applications (Table 1). Figures 1-3 show examples of the remarkable effectiveness of the irradiation treatments on the quality of onions, potato and strawberries.

Table 1

Applications of Irradiation Treatment of Food

Table 1

Applications of Irradiation Treatment of Food

Application

Food

Dose (kGy)

Control of Pathogens

Poultry, Meat, Seafood

0 0

Post a comment