Silver News

By Jeffrey R. Ellis, Technical Consultant to the Silver Institute

In a world where there is increasing concern over the safety of food and how it is processed, packaged and stored, silver-based biocides are being evaluated for many different purposes. Sales of silver for such purposes are still small, less than 10,000 ounces world wide, and mostly in Japan and in Europe, but major growth is expected.

Silver, because of its antibacterial qualities, offers greater hygiene, control of odor, and prevention of discoloration and structural damage in processing areas. Use of silver-based biocides also offers reduced downtime because there is less need to take processing equipment offline 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 lower. Silver-based biocides in packaging can also help keep the foods inside fresh for longer periods of time, but are generally too expensive to be used on throw-away items. For cost-effective adoption, a minimum of a 1,000 fold decrease in pathogen count is necessary and often a 100,000 fold decrease is necessary to really

Meat and poultry processors are taking increasingly more steps to minimize any possible build up of particularly virulent pathogens such as E. Coli H157:O7 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 have traditionally not had 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 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 in the process of contacting 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 United States, for example, the FDA oversees food contact applications, and the EPA oversees non-food contact surfaces such as walls, floors, ceilings, and climate control ducting. The National Sanitation Foundation of Ann Arbor, Michigan, a nongovernment organization, sets industry standards often codified by government regulators worldwide for silver coated contacting parts in ice and potable water processing machinery. The US 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 and success is likely.

Silver News - Fourth Quarter 2004