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Food Irradiation

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  1. The invention of television or a succession of discoveries
    1. The discoveries that introduced the invention of television
    2. The birth of the term "television"
    3. From the mechanical television (1925-1931) to the electric television (1932-1945)
  2. Television in the footsteps of players like the radio
    1. The FCC and Congress: state control
    2. The networks: diffusion
    3. U.S. companies: financing
  3. Television and the American public
    1. Television proved to the Americans
    2. The placing of television sets on the market
    3. Programs
  4. Conclusion

Food irradiation is the process of exposing food to ionizing radiation of radioactive isotopes of cobalt, cesium and accelerators which produce controlled amounts of beta rays or ?-rays on foods. We will study the characteristics of radiation and their effects, on the physical, chemical and biological levels. Then, we will focus on its use in the food industry to improve the processes of food preservation. Finally, we will discuss the most delicate point of demonstrating that a food has been irradiated in order to ensure trust and safety of consumers. We will also study the different methods of detection.

Research studies conducted in the last 40 years have shown that food irradiation can be used to destroy insects and parasites in cereal grains, dried beans and fruits, vegetables, meat and seafood. Further application includes sprout inhibition in crops like potatoes and onions, to delay the ripening of fruits and vegetables and to reduce the number of micro-organisms in the food. The radiation processing of food is done in order to increase their shelf life or improve their hygienic quality, while preserving the best of their organoleptic characteristics, health and nutrition.

The two methods used for irradiation are:
? Electron beams:
? Electromagnetic radiation

Ionization that is applied to food irradiation has three objectives:
1 - A low dose, harm the reproductive organs of insects so controls their proliferation
2 - A higher dose reaching the biochemical mechanisms of microorganisms (bacteria, yeasts and molds), reduces their proliferation and eventual revival of spores
3 - A very low dose reduces the activity of apical meristems of living organisms.

In all three cases, the intensity of the effects depends on the degree of ionization.

Comparison between beta rays and gamma rays:
Since these are the two types of radiation that are used in the most developed of food industries, it is interesting to compare some of their characteristics:

Origin:

Beta radiation is produced electrically, with electron accelerators. The source, therefore, depends on the electric current and can be started or stopped on command.
Gamma radiation is produced by nuclear power and emits radiation continuously.

The ability to penetrate:

Beta rays: The dose to be deposited is defined fairly precisely and must be as homogeneous as possible throughout the treated volume. The desired effects would not be achieved at points that receive a dose that is too low. Side effects appear at the irradiated points.Penetration depends only on the amount of material that is traversed. It is inversely proportional to the product density. It is 3.4 in water and would be 3.4 / D in a food density of D.
However, two-sided treatment increases the penetration (8 / D) and encourages a better homogeneity of the dose.

Gamma rays:
Each unit of thickness of the material is encountered by the radiation. The material absorbs the same amount of energy that is received. This is an exponential decrease. When the power of penetration is higher, it ensures uniformity in the treatment of large volumes and high thicknesses.

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