- August 01, 2004, by Dr. Richard M. Podhajny, Ph.D. Contributing Editor
If you have been to the store lately, you may have noticed the number of new products that provide antimicrobial protection. It might be an air filter, a toothbrush, or a packaging material. The use of antimicrobial additives in various products is on a fast track as consumers demand more safety insurance against the harmful microbes we encounter daily at home and in the workplace.
Microbes are organic living organisms invisible to the naked eye but can be seen under a microscope. They include bacteria, fungi, algae, protozoans, and viruses. Bacteria are the oldest form of life on Earth and have been around for billions of years. Many microorganisms are necessary for human life, and only a small number are problematic. Among problematic bacteria of primary concern to the packaging industry are salmonella, E. coli, listeria, staphylococcus, and pseudomonas.
In addition, packaging products can be subjected to undesirable fungi, of which yeast and mold are the main concerns.
Microbe contamination in packaging materials typically is controlled by heat, steam, radiation, or the addition of antimicrobial additives. Antimicrobials used in packaging materials vary in chemistry, application, and effectiveness. No one antimicrobial additive can provide the necessary safety characteristics as well as extend the shelf life for the large number of packaged products in the marketplace.
Balancing antimicrobial properties and their effectiveness depends not only on the antimicrobial additive but on the substrate and the perishable food products themselves.
There are many antimicrobial products that work for selected food packaging products. These can be inorganic or organic materials as well as their salts. Antimicrobial additives come in all sizes and various chemical forms. Among the most popular antimicrobial additives are organic acids, salts, vitamins, Nisin, and inorganic materials.
The focus of this article is the use of triclosan, silver zeolites, and chlorine dioxide.
One of the oldest antimicrobials used in a variety of industries is triclosan. It is used in treating water and is found in toothpaste, soaps, cosmetics, and packaging products.
This antimicrobial, which is a chlorinated derivative of phenol, in recent years has come under scrutiny from several perspectives, including its ability to create more-resistant bacteria. Studies suggest it can produce polychlorinated dioxins and furans under UV or sun exposure. As a result, heath concerns related to its use have been expressed in the US as well as in Europe. These concerns may lead to a reduction in its use.
Chlorine dioxide use has extended from treating water to controlling microbiological growth in various industries such as dairy, beverage, fruit and vegetables, as well as in various food processing applications. More recently this chemistry is being incorporated into food packaging. Chemicals that can produce chlorine dioxide when in contact with moisture can be incorporated into the film extrusion process to produce treated films that incorporate this antimicrobial product.
Bernard Technologies offers a proprietary chlorine dioxide system called Microsphere. A paper describing the technology will be presented at the upcoming TAPPI 2004 Place Conference in Indianapolis, IN, in late August.
Another effective antimicrobial chemistry is the use of silver zeolites. Silver zeolites release silver ions that are very effective in protecting food packages from cross contamination. Unlike the chlorine dioxide, use of silver zeolite does not provide antimicrobials in the package head space but works by direct contact. Coatings formulated with silver zeolite have been shown to deliver effective and long-lasting antimicrobial characteristics.
Antimicrobial packaging is an extremely demanding science in terms of efficacy and delivery. If the antimicrobial compound migrates to the food product, it must be considered a food additive, appear on the food label as such, and have the necessary regulatory approvals. If the substrate is treated with a non-migratory antimicrobial, then it protects the package but not necessarily the food product.
Dr. Richard M. Podhajny has been in the packaging and printing industry for more than 30 years. Dr. Podhajny works at Colorcon, which will present a paper at the TAPPI 2004 Place Conference on its commercialization of silver zeolite inks and coatings. Contact him at 267/695-7717; firstname.lastname@example.org.