Basics of Disinfection

Liquid cleaning products can contain disinfection agents.

While many bacteria are harmless, some cause diseases in humans. These bacteria can be destroyed by disinfection. Disinfection differs from the similar process of sterilization, because sterilization processes kill all biological organisms, while disinfection may leave some organisms unharmed. This means that disinfection is not as safe as sterilization as a disease-prevention process.

Pasteurization

Pasteurization uses heat to destroy harmful bacteria. The milk and fruit juice industries use flash pasteurization, or heating the liquid product to a high temperature for a short period, typically between three and 15 seconds, to kill harmful bacteria. Another type of pasteurization, steam pasteurization, uses pressurized steam to heat the surface of a product, such as a beef carcass, in order to disinfect it. The item is steamed at temperatures of up to 200 degrees Fahrenheit for six to eight seconds. Poultry, fruits, vegetables and red meat products may be disinfected through a process known as irradiation pasteurization. Gamma radiation used in this process kills the harmful bacteria.

Ultraviolet Disinfection

Water treatment plants in the United States use ultraviolet light to disinfect water. Ultraviolet light penetrates the cell walls of harmful bacteria in the water and prevents them from reproducing. Ultraviolet disinfection uses a lamp emitting radiation in the form of light at a wavelength of between 250 and 270 nanometers to disinfect water and other food products. Bottled water producers also use ultraviolet light to disinfect their products, as do some fish and meat processing companies. Ultraviolet light disinfects these products without contaminating them with chemicals.

Washer and Flushing Disinfection

Medical institutions use flushing and washing machines to disinfect equipment and objects such as bedpans and reusable surgical equipment. Closed washing machines flush objects with warm water, typically mixed with a detergent. Then, flushing with hot water or steam disinfects them. Machines used to disinfect surgical equipment run for 20 to 30 minutes and use water heated to a temperature of 90 degrees Celsius.

Chemical Disinfection

Joseph Lister, the surgeon who revolutionized surgical hygiene, used phenol or carbolic acid as a disinfectant. Derivatives of phenol penetrate the cell walls of bacteria and destroy them by causing enzyme systems to shut down. The breach in the cell wall also allows essential cellular material to leak out. Peracetic acid and hydrogen peroxide are also used as chemical disinfectants. In combination they can render all bacteria that they contact inactive within 20 minutes. Peracetic acid and hydrogen peroxide do not, however, destroy bacterial spores.

References

• Centers For Disease Control: Glossary
• Food Safety Site at Clemson University: Describe Pasteurization
• West Virginia University: Ultraviolet Disinfection
• Centers For Disease Control: Guideline For Disinfection and Sterilization in Healthcare Facilities, 2008
• Centers For Disease Control: Guideline For Disinfection and Sterilization in Healthcare Facilities, 2008: Peracetic Acid and Hydrogen Peroxide
• Food Processing Technology: UV Disinfection for Meat and Fish, Hanovia, United Kingdom

Resources

• Centers For Disease Control: Home