Enhancing Food Safety and Shelf Life through the Principle of Food Irradiation

Food irradiation is a crucial process in ensuring the safety and longevity of our food supply. By subjecting food to controlled amounts of radiant energy, this method effectively eliminates harmful bacteria and parasites, thereby reducing the risk of foodborne illnesses.

The concept of irradiation was first proposed in 1897, shortly after the discovery of X-rays by Roe¨tgens. Its potential was recognized early on, leading to its patenting in England in 1905. However, it wasn't until the 1940s to 1960s that significant research and development occurred, notably at the quartermaster laboratory of the US Army. This research aimed to provide sterilized cans for military use, highlighting the importance of food safety, particularly in challenging environments.

The pivotal moment came in 1962 with the establishment of the first food irradiation facility for the army. Subsequently, in 1963, the USDA issued the first food irradiation rules, primarily focusing on decontaminating wheat and wheat powder. This marked the formal recognition of food irradiation as a viable method for enhancing food safety.

Various sources of ionizing irradiation, such as gamma rays, X-rays, and electrons (known as Radura), are utilized in the process. When radiation interacts with food, it disrupts molecular structures, leading to the formation of ions or free radicals. These free radicals are instrumental in killing microorganisms by damaging their DNA and creating toxic reactive compounds within microbial cells, effectively neutralizing bacteria, spores, insects, and enzymes.

The advantages of food irradiation are manifold. Firstly, it results in fewer nutritional losses compared to other preservation methods. Additionally, while the chemical reactions associated with irradiation produce small amounts of radiolysis products, extensive research has shown that these compounds are harmless and pose no significant health risks to consumers.

In conclusion, food irradiation stands as a cornerstone in ensuring food safety and extending shelf life. Its historical evolution, coupled with its scientific principles and demonstrated advantages, underscores its importance in modern food processing and preservation practices.
Enhancing Food Safety and Shelf Life through the Principle of Food Irradiation

Ohmic heating process

Both irradiation and microwave heating employ radiant energies which effect foods when their energy is absorbed, whereas ohmic heating raises the temperature of foods by passing an electrical current through the food.

When electrical current flows through a conductor, the motion of charges within the material results in agitation of molecules therein. This results in increased temperature.

Within metallic conductor, the moving charges are electrons; however, within food materials, the charges are usually ions or other charged molecules such as protein, which migrate to the electrode of opposite polarity.

Because heating occurs by internal energy generation within the conductor, the method results in a remarkably even distribution of temperatures within the material. Ohmic heating is alternatively called resistance heating or direct resistance heating. This due to food system serves as an electrical resistance.
Ohmic heating process

Principle of Food Preservation

Principle of Food Preservation
The basic principles of food preservation primary involves the process of inhibiting

• The growth and activity of microorganism

• Activity of endogenous enzymes

• Chemical reactions which may deteriorate the quality of food

• Invasion and spoilage by insects and rodents

In addition, spoilage of food may be caused during mechanical handling, processing, packaging, storing and transportation. Appropriate care has to be exercised to prevent deterioration of quality of food.

Several methods are available for preservation of food based on the above principles, the method include:

• Preventing the accessibility of food to microorganism by asepsis and packaging

• Physical removal of microorganisms from food by filtration or centrifugation

• Hindering the growth and activity of microorganism by use of preservatives, use of low temperatures atmospheric control in packaging and storing of foods and decreasing water activity in foods by drying or evaporation

• Killing the microorganism by use of high temperature and ionizing radiation

• Inactivation of endogenous enzymes by moderate heating

• Inhibition of chemical reaction through the use of chemical additives

• Fermentation of foods to yield more stable or less perishable food product

Food preservation as it is practiced in the industry always involves the use of combination of methods for achieving maximum effectiveness.

Asepsis or preventing the accessibility of food to microorganisms is well exemplified in nature, the protective covering in natural foods such as skins on fruits and vegetables, shells on eggs and nuts and skins and membranes on livestock and fish prevent the attack by microorganisms and maintain the living tissues in healthy condition.

Microbial attack is facilitated only after the death of the animal or when the skin is physically damaged. Packaging of foods and food products in a variety of materials such as metal cans, plastic films pouches, bags or boxes, paper bags or cartons and glass bottles provide effective protection against microbial attack.

Filtration or centrifugation is adopted to physically remove microorganisms particularly in liquid foods such as milk, soft drinks, fruits juices and alcoholic beverages such as wine and beer.
Principle of Food Preservation