Antimicrobial Agents for Ready-to-Eat Meat Products

Antimicrobial Agents for Ready-to-Eat Meat Products

There are a number of antimicrobial agents currently available for meat processors that assist in minimizing the growth and/or survival of Listeria monocytogenes.  Some of these are ingredients which would be added to the product formulation; others are used as surface applications to either destroy surviving L. monocytogenes or prevent its growth.

There are two different effects on pathogens, both of which are important for producing safe meat products, and they are bacteriocidal and bacteriostatic.  Bacteriocidal means that the treatment destroys the pathogen.  Bacteriostatic means that the treatment prevents L. monocytogenes from growing and increasing in numbers on the product, if the product is contaminated with L. monocytogenes from the processing environment after cooking.  Validated use of a process or ingredient, which has either bacteriocidal or bacteriostatic effects on L. monocytogenes will allow an inspected processor to operate under Alternative 2.  If an antimicrobial agent is used with RTE products which offer both bacteriocidal and bacteriostatic effects, then those products could be made under Alternative 1.

This article will briefly summarize some of the potential antimicrobial agents that are available for processors.  And this article is intended to be a prelude to a OAMP Convention program, in March, in which the plan is for the use of these products to be demonstrated  and to have suppliers of these ingredients available to answer questions about their specific products.

There are many antimicrobial agents being studied for their bacteriocidal and bacteriostatic effects of L. monocytogenes, however, while many are very effective, many have not found commercial success with the larger processes either because of prohibitive costs or negative quality effects on the finished RTE products.

The most commonly used antimicrobial agents in the meat industry today are lactates and diacetates, which are added to product formulations before cooking.  Sometimes, lactates are sold alone, however, it is generally recognized that a combination of lactates and diacetates are more effective in preventing L. monocytogenes on RTE meat products.  These ingredients are salts of organic acids and may cause some flavor problems, if they are used at too high of a level or if the product is very mildly flavored.   Acetate is the salt of acetic acid, which is the effective ingredient in vinegar. 

Research has shown that these ingredients vary in their effectiveness, possibly as a result of who is manufacturing the ingredients or possibly due to the product composition and processing procedures used.  Therefore, validation of the effectiveness of these ingredients would be valuable to ensure that they are doing what they were intended to do in RTE meat products.

Surface application of organic acids may also be effective in preventing L. monocytogenes and one approach is to combine acetic acid with lemon juice.  This combination allows for a “clean” label, that some consumers may find desirable.  L. monocytogenes contamination of RTE products is typically a surface phenomenon, such that a surface application of an antimicrobial agent would seem logical.  Also, pulling a vacuum around a product that has been treated by an antimicrobial agent would cause the antimicrobial agent to be well distributed over the entire surface of the RTE product.                                                              

By Lynn Knipe, Ohio State University

The combination of buffered sodium citrate and sodium diacetate offers a double layer of protection for RTE meat products by inhibiting L. monocytogenes growth, as well as Clostridium perfringens germination and outgrowth during post-cook chilling.

There is also a liquid smoke extract which is a colorless, flavorless liquid that is applied as a spray or shower onto product or as a dip just prior to packaging to prevent growth of Listeria monocytogenes.

Lauric arginate is also being sprayed onto either the surface RTE meat products, or into the pouch immediately prior to packaging.  As mentioned earlier, surface application of antimicrobial agents in combination of vacuum packaging relies on the fact that the purge is distributed evenly over the entire product surface inside a package.