Silver lining for food processing

In a world where there is increasing concern over the safety of food and how it is processed, packaged and stored, health experts are turning increasingly to silver-based biocides. The biocides are chemical agents capable of destroying living organisms.

Sales of silver for use in biocides are still small (less than 10,000 oz. worldwide, and mostly in Japan and Europe), but major growth is expected.

Silver, because of its antibacterial qualities, offers greater hygiene, control of odour, and prevention of discolouration and structural damage in processing areas. Use of silver-based biocides also offers reduced downtime, because there is less need to take processing equipment off-line for cleaning. Additional uses are in specialty packaging, occupational clothing worn by food processing workers, prevention of pathogen build-up in climate control systems, and on floors, walls and ceilings of food processing and storage facilities.

Hygiene needs are greatest for meat and poultry processing because of the danger of potentially deadly microbes such as salmonella and listeria. Dairy and bakery products can also be a large potential market for control of pathogens in processing areas. Ice-making and beverage preparation also make use of silver biocide coated parts in processing machinery. So far, there has not been any use or need for the processing and packaging of fresh fruits and vegetables as the pathogen danger is relatively low.

Silver-based biocides in packaging can also help keep the foods inside fresh for longer periods of time, yet they are generally too expensive to be used on throw-away items.

More and more, meat and poultry processors are taking steps to minimize any possible build-up of particularly virulent pathogens such as E. coli and listeria.

Current steps include welding of metals and other components of machinery so that no biofilms suitable for supporting pathogens can form in small or narrow spaces. Stainless steel surfaces, especially for meat and poultry, are widely used and traditionally have not posed problems. Meat and poultry processors also use other well-established processes, such as washing and bleaching, high-energy irradiation, and organic antimicrobial treated parts and surfaces. The American Meat and Poultry Institute (AMPI) has published a pamphlet on the principles of sanitary design for meat and poultry processing plants. The AMPI is aware of the possible beneficial effects of silver for meat and poultry processing and packaging, and the Silver Institute is consulting with the AMPI in order to develop further potential uses of silver-based biocides.

Different government and non-government entities are involved in keeping foods safe. In the U.S., for example, the Food and Drug Administration (FDA) oversees food contact applications, and the Environmental Protection Agency oversees non-food contact surfaces, such as walls, floors, ceilings and climate-control ducting. The National Sanitation Foundation of Ann Arbor, Mich., a non-government organization, sets industry standards often adopted by government regulators worldwide for silver-coated contacting parts in ice and potable water processing machinery. The U.S. Department of Agriculture only rarely gets called in for meat and poultry inspections.

Use of biocides in food processing in the U.S. is likely to undergo more detailed scrutiny by the FDA. The agency is starting to look more carefully at health effects of both one-time and cumulative biocide intake resulting from the use of these chemicals. It must be remembered that although food and beverages can come into contact with biocide-treated surfaces, these biocides must not become food or beverage ingredients. Consequently, it must be demonstrated that all biocides remain bound to the surface and do not leach into the food.

Most food processors in North America are just beginning to be acquainted with products containing silver-based biocides.

Experience in Japan and Europe indicates that adoption in U.S.-based food- processing facilities remains likely.

— The preceding is from Silver News, a quarterly publication of the Washington, D.C.-based Silver Institute.