Humans have attempted to preserve f

Humans have attempted to preserve food products from the detrimental effects of micro- organisms since prehistoric times. Processes such as heating, drying, fermentation, and refrigeration have been used to prolong the shelf-life of food products. Some chemical food preservatives, such as salt, nitrites, and sulfites, have been in use for many years, however some have seen extensive use only recently. One of the reasons for the increased use of chemical preservatives has been the changes in the ways foods are produced and marketed. Today, consumers expect foods to be available year-round, to be free of food- borne pathogens, and to have a reasonably long shelf-life. While some improvements have been made using packaging and processing systems to preserve foods without chemicals, today antimicrobial food preservatives still play a significant role in protecting the food supply.
In selecting a food antimicrobial agent, several factors must be taken into consider- ation (Branen, 1993). First, the antimicrobial spectrum of the compound to be used must be known. This, along with knowledge of the bioburden of the food product, will allow the use of correct antimicrobial agent for the microorganism(s) of concern. Second, the chemical and physical properties of both the antimicrobial and the food product must be known. Such factors as pKa and solubility of the antimicrobial and the pH of the food will facilitate the most efficient use of an antimicrobial. Third, the conditions of storage





of the product and interactions with other processes must be evaluated to ensure that the antimicrobial will remain functional over time. Fourth, a food must be of the highest microbiological quality initially if an antimicrobial is to be expected to contribute to its shelf-life. None of the antimicrobials discussed in this section is able to preserve a product that is grossly contaminated. In most cases, while food antimicrobials will extend the lag phase or inactivate low numbers of microorganisms, their effects can be overcome. With rare exceptions, food antimicrobials are not able to conceal spoilage of a food product, i.e., the food remains wholesome during its extended shelf-life. Because food antimicrobi- als are generally bacteriostatic or fungistatic, they will not preserve a food indefinitely. Depending upon storage conditions, the food product will eventually spoil or become hazardous. Finally, the toxicological safety and regulatory status of the selected compound must be known.
This chapter will focus on food antimicrobials approved by regulatory agencies for use in foods as direct additives. For each antimicrobial or class of antimicrobials, character- istics of the compound(s), the antimicrobial spectrum, the antimicrobial effectiveness in foods, the mechanism of action, applications, regulations, and toxicology are discussed. The detail of the discussions varies depending upon research available and importance of the compounds.