UV rays are used in food preservation to control microorganisms. UV light has poor penetration so it is only effective on surface microbes. The most effective wavelength is 260nm which is absorbed by nucleic acids in microbes. UV light is used to tenderize meat, cure and wrap cheese, prevent mold on bakery products, purify air in processing, treat water, and disinfect equipment. The mechanism is that UV light causes photochemical changes and mutations in nucleic acids that can lead to cell death.

1. Basura J Jayasundara 1
PHYSICAL METHODS OF FOOD PRESERVATION
Use of Light Energy in Food Preservation
UV rays are nonionizing radiation and it is widely used in the food industry to control
microorganisms by the use of UV lamps. Poor penetrative power of the UV light limits its use to
surface application. The most effective wavelength against microorganism is around 260 nm
which correspond to a strong absorption by nucleic acid bases. Few applications of UV light in
food industry as follows.
 Tenderization or aging of meat
 Curing and wrapping of chees
 Prevention of surface mold growth on bakery products
 Air purification in food processing industry
 Water treatment
 Disinfection of equipment, glassware
Figure : Use of UV light in food industry
Mode of action
Due to the low penetrating power of the UV rays, lethal action against microbes is confined to
organisms on or near the surface of the materials. It is absorbed by proteins and nucleic acids, in
which photochemical changes are produced that may lead to cell death. The mechanism of UV
death in the bacterial cell is the production of lethal mutations as a result of action on cell nucleic
acids. On the other hand degradation of the bacterial cell walls also can cause the germicidal
effect.

2. Basura J Jayasundara 2
REFERENCES
 Adams, M.R., and Moss, M, O., 2008. Food Microbiology, third edition. RSC publishing,
UK.
 Ray, B., Fundamental Food Microbiology, third edition, 2004. CRC press.
 Jay, J.M., Loessner, M.J., and Golden, D.A., Modern Food Microbiology, seventh edition,
2005. Springer.
 Rahman, M.S., Handbook of Food Preservation, second edition, 2007. CRC press.
 www.fda.gov/Food/ResourcesForYou/Consumers/ucm261680.htm