Since environmental exposure is a major source of Listeria monocytogenes contamination on fully cooked ready-to-eat products, cook-in-the-bag processing has become very important. By not exposing the product to the environment between cooking and packaging, the chance of Lm contamination is eliminated, which reduces the need for some of the antimicrobial agents and the post-packaging pasteurization process to eliminate Lm on ready-to-eat meat products.
Cook-in-the-bag deli products were being made safer for consumers long before processors were aware of the risk of environmental contamination by Lm. Assuming that the cooking procedure provides sufficient lethality, there should be no Lm in the package up to the point that the package is opened by the end-user. This product has long been understood to have a shelf life that was more than twice as long as products that were exposed to the environment, before the final vacuum-packaging process. Using steam or water cooking methods, this product also cooks faster than the traditional oven-cooked products.