Fish Microbiology and Quality Assurance

4.4. Food preservation by radiation

Unit 4 - Food preservation techniques and microorganisms

4.4. Food preservation by use of radiation
Radiations have potential application in food preservation because of their destructive effect on microorganisms. Radiation is defined as the emission and propagation of energy through space or material medium. However, in food preservation electromagnetic radiations (EM) are important and these are self propagating eclectic or magnetic waves or vibrations of different wavelength. Generally, radiations of shorter wavelength are more damaging to microorganisms than long wavelengths.

EM radiations of importance in food preservation
The EM radiations of importance in food preservation are;

• Ultra violet rays
• X – rays
• Gamma rays
• Microwaves

In food preservation ionizing radiations of wavelength of 2000 A^o or less are important. These include beta rays; Gamma rays and X – rays. Ionizing radiations ionize molecules on their path and thus destroy microorganisms without raising temperature. Killing of microorganisms in foods using electromagnetic radiations without raising temperature is termed as cold sterilization. Ionizing radiations have high energy level to cause ejection of an orbital electron from an atom or a molecule.