Why Your Deli Meat Gets Slimy

There's something about cold cuts that speaks to our very souls. Perhaps it's the comfort of familiarity, the combination of flavors and textures perfectly tailored to our preferences. So, when it's sandwich time, nothing hurts more than getting to the fridge only to find our deli meat coated with an unappetizing slimy film. What is that stuff anyway?

The reason for your lunch meat's untoward sliminess boils down to a genus of bacteria called Lactobacillus.  Lactobacillus bacteria consume the sugars in our food and convert it to lactic acid. The slime on your sandwich meat is a byproduct of this process. Before you hear the word bacteria and start running for the garbage can, this isn't necessarily one of those signs that your food has gone bad. Remember, some bacteria are good!

Lactobacillus is generally considered safe to consume. As a matter of fact, it is even added to some foodstuffs for preservation and to produce certain desirable effects such as the sour flavor in yogurt. However, the Lactobacillus on your deli meat wasn't intentionally added. It was likely acquired during the packing process. While this isn't inherently a bad thing, it can eventually lead to food spoilage under the right conditions.

Eventually, the presence of Lactobacillus will cause a slimy film on deli meat as it naturally begins to break down. However, whether or not it also contributes to an increased rate of food spoilage depends on the strain. While homofermentative strains create little else but lactic acid and the things we like about fermentation, heterofermentative strains generally create an abundance of ethanol, carbon dioxide, and other gasses that create unsavory odors, textures, and colors. This happens at an increased rate when deli meats aren't stored in an airtight container at the proper temperature (40 degrees Fahrenheit or lower). These are a couple of mistakes everyone makes with deli meats that can be easily avoided.

How long is lunch meat safe to eat? The U.S. Department of Agriculture recommends consuming deli meat within three to five days after opening it. However, others are more keen to use their senses to figure out whether or not their food should go to waste. If it has an off color and unpleasant smell, it's probably time to trash it.