Control by Irradiation ◾ 511
UV Radiation
Microorganisms are especially susceptible to UV light between 200 and 280 nm. Because of low
penetration power, it has been used to inactivate microorganisms on the surface of foods (meat,
fish, and bread) as well as in air and on walls, shelves, and equipment in the food handling and
processing area. In addition, liquids, such as water and syrups, in thin layers, have been treated
with UV.
Conclusion
Irradiation, like heat, kills microbial cells and destroys their spores at a predictable rate that is basically dependent on dose level, exposure time, and microbial type. Its effectiveness on microbial
control in food has been well studied since the beginning of the 20th century. Although irradiated
foods have been found to be safe, many consumers view them as unsafe. As a result, irradiation is
used in a limited way in food. It is expected that with proper education of consumers on the safety
of irradiated food, consumers’ demand will increase and irradiation will be used to destroy many
foodborne pathogens in raw and processed foods. In recent years, several other methods that can
be used to kill microorganisms effectively have been studied and are discussed in Chapter 40.
QUESTIONS
1. Briefly discuss why irradiated foods are not commercially successful in many countries.
2. Explain the mechanisms of antimicrobial actions of irradiation by γ-ray and UV light.
3. List the factors that can reduce or increase the antimicrobial effectiveness of irradiation in
food.
Figure 39.1 (See color insert.) Logo for irradiated foods. the Codex Alimentarius, an international committee on food safety, has developed this logo to put in green color on the package of
irradiated foods. irradiated foods from the United States are labeled with this logo, along with
the words “treated with Radiation” or “treated by irradiation.”
UV Radiation
Microorganisms are especially susceptible to UV light between 200 and 280 nm. Because of low
penetration power, it has been used to inactivate microorganisms on the surface of foods (meat,
fish, and bread) as well as in air and on walls, shelves, and equipment in the food handling and
processing area. In addition, liquids, such as water and syrups, in thin layers, have been treated
with UV.
Conclusion
Irradiation, like heat, kills microbial cells and destroys their spores at a predictable rate that is basically dependent on dose level, exposure time, and microbial type. Its effectiveness on microbial
control in food has been well studied since the beginning of the 20th century. Although irradiated
foods have been found to be safe, many consumers view them as unsafe. As a result, irradiation is
used in a limited way in food. It is expected that with proper education of consumers on the safety
of irradiated food, consumers’ demand will increase and irradiation will be used to destroy many
foodborne pathogens in raw and processed foods. In recent years, several other methods that can
be used to kill microorganisms effectively have been studied and are discussed in Chapter 40.
QUESTIONS
1. Briefly discuss why irradiated foods are not commercially successful in many countries.
2. Explain the mechanisms of antimicrobial actions of irradiation by γ-ray and UV light.
3. List the factors that can reduce or increase the antimicrobial effectiveness of irradiation in
food.
Figure 39.1 (See color insert.) Logo for irradiated foods. the Codex Alimentarius, an international committee on food safety, has developed this logo to put in green color on the package of
irradiated foods. irradiated foods from the United States are labeled with this logo, along with
the words “treated with Radiation” or “treated by irradiation.”