The Thai Journal of Veterinary Medicine


The prevention of human fecal contamination of food and water is an effective measure to control the transmission of foodborne disease viruses e.g. hepatitis A virus (HAV) and calicivirus found in food chains and water systems. If the prevention of virus contamination is not successful, one of the most common critical control points in the food industry is the inactivation of viruses that contaminate the food or water. The objective of inactivation is to modify the virus or make it abort in the next replicative cycle. The efficiency of inactivating agents is measured by the plots of "logarithmic scale of plaque forming units of virus" versus the "inactivating dose". The slope of the best-fit straight line is the rate of inactivation by a specific agent. Ultraviolet (UV) light and hypochlorite are used to disinfect water, food surfaces and food-contact surfaces. The most common inactivation method in food preparation and processing is heat. The virucidal wavelength of UV is 253.7 nanometers and the decimal inactivation doses of viruses are between 1-25 mWs/cm2. Depending on pH, hypochlorous acid (HOCl) inactivates viruses more effectively than the hypochlorite ion (OCl-). Thermal treatment inactivates virus at a temperature above 60oC in minutes. Some gram-positive bacteria e.g. Micrococcus luteus and Staphylococcus epidermidis enzymatically inactivate enteroviruses. HAV and feline calicivirus appears to be more resistant to inactivation than other picornaviruses and coliphages. Inactivation methods have different mechanisms of action in which the target is not mutually exclusive and may be controversial. In essence, the viral capsid is the primary target of chlorine, thermal, biodegradation, drying and formaldehyde inactivation while the primary target of UV inactivation is the viral RNA.

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