Antimicrobial additives have been used successfully for many years as direct food additives. The literature provides evidence that some of these additives may be effective as indirect food additives incorporated into food packaging materials. Antimicrobial food packaging is directed toward the reduction of surface contamination of processed, prepared foods such as sliced meats and Frankfurter sausages (hot dogs). The use of such packaging materials is not meant to be a substitute for good sanitation practices, but it should enhance the safety of food as an additional hurdle for the growth of pathogenic and/or spoilage microorganisms. Studies have focused on establishing methods for coating low-density polyethylene film or barrier films with methyl cellulose as a carrier for nisin. These films have significantly reduced the presence of Listeria monocytogenes in solutions and in vacuum packaged hot dogs. Other research has focused on the use of chitosan to inhibit L. monocytogenes and chlorine dioxide sachets for the reduction of Salmonella on modified atmosphere-packaged fresh chicken breasts. Overall, antimicrobial packaging shows promise as an effective method for the inhibition of certain bacteria in foods, but barriers to their commercial implementation continue to exist.

Antimicrobial additives can be successfully incorporated into food packaging films or film coatings. However, several factors affect their effectiveness for inhibition of spoilage or pathogenic microorganisms. Nisin was coated onto low density polyethylene film using a cellulose based coating. It inhibited growth of Staphylococcus aureus and Listeria monocytogenes within 48h in a nonfood system. Other studies using different coating material, methods and antimicrobial agents are reviewed. Several factors affecting the effectiveness of antimicrobial packaging materials are also discussed.Surface growth of microorganisms is one of the leading causes of food spoilage. Natural microflora can eventually spoil the food or surfaces can be contaminated by handling during processing and packaging. For many years foods have been treated with antimicrobial agents however, packaging materials may also provide the same benefits using similar or different additives. A packaging system that allows for slow release of an antimicrobial agent into the food could significantly increase the shelf life and improve the quality of a variety of foods. The use of these packaging systems are not meant as a "cover up" for poor quality control. It can, however, serve as an additional protective measure to help ensure safe and high quality foods.The purpose of this paper is to provide information regarding the types of antimicrobial films used, their effectiveness and factors that influence their effectiveness. First a specific study done in our laboratory using nisin as an antimicrobial agent coated onto LDPE film will be covered. Then a review of other studies using different types of antimicrobial packaging systems follows. Finally the factors that affect the implementation of an antimicrobial packaging system will be discussed.

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The objective of this study was to determine the effectiveness of packaging films coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing 10,000, 7,500, 2,500, or 156.3 IU/ml nisin for controlling Listeria monocytogenes on the surfaces of vacuum-packaged hot dogs. Barrier film coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing nisin or no nisin (control) was heat sealed to form individual pouches. Hot dogs were placed in control and nisin-containing pouches and inoculated with a five-strain L. monocytogenes cocktail (approximately 5 log CFU per package), vacuum sealed, and stored for intervals of 2 h and 7, 15, 21, 28, and 60 d at 4 degrees C. After storage, hot dogs and packages were rinsed with 0.1% peptone water. Diluent was spiral plated on modified oxford agar and tryptic soy agar and incubated to obtain counts (CFU per package). L. monocytogenes counts on hot dogs packaged in films coated with 156.3 IU/ml nisin decreased slightly (approximately 0.5-log reduction) through day 15 of refrigerated storage but was statistically the same (P > 0.05) as hot dogs packaged in films without nisin after 60 d of storage. Packaging films coated with a cellulose-based solution containing 10,000 and 7,500 IU/ml nisin significantly decreased (P < 0.05) L. monocytogenes populations on the surface of hot dogs by greater than 2 log CFU per package throughout the 60-d study. Similar results were observed for hot dogs packaged in films coated with 2,500 IU/ml nisin; however, L. monocytogenes populations were observed to be approximately 4 log CFU per package after 60 d of refrigerated storage from plate counts on tryptic soy and modified oxford agars.