If an open packet of salami has been sitting in your fridge for almost a week, there's good reason to believe it's time to throw it out.

There's usually a few indications that your days-old deli meat is past its peak, but sometimes, there might not always be visible signs of spoilage.

Exactly how long does deli meat actually last, and what steps should you take to store it correctly? To understand the risks of consuming deli meat, we asked an expert to answer your FAQs.

How long is deli meat good for?

Official recommendations say deli-sliced or store-prepared lunch meat should be consumed within three to five days, according to the U.S. Department of Agriculture. Additionally, any opened vacuum-packets of sliced lunch meat should be consumed within three to five days. Unopened packets should be consumed within two weeks, the USDA recommends.

These recommendations run on the contingency that you've taken the steps to ensure the safe storage of deli meat. "What is critical is how the deli meat is conserved," says Dr. Stephanie Seveau, PhD, a professor of microbial infection and immunity at The Ohio State University School of Medicine. Deli meat should be refrigerated at 40 degrees Fahrenheit or below, according to the USDA.

After you've purchased any type of sliced lunch meat, be sure to refrigerate it immediately once you get home. If the deli meat is left out for a few hours "at a temperature that favors bacterial growth," there will be risks to consuming it, Seveau says.

How can I tell if deli meat has gone bad?

There's a few telltale signs that may indicate it's time to discard an open packet of deli meat. Do not consume the meat if you notice any suspicious changes to its smell or appearance. For example, you should discard the meat if it is emanating an unpleasant smell, if a viscous, sticky film appears on it, or if there is mold growth, Seveau says.

However, it is important to note that there won't always be visible indications of bacterial growth on deli meat. Listeria growth, for example, often does not have any smell, Seveau says.

For this reason, always be sure to discard deli meat that has been open for more than five days, per USDA recommendations. Additionally, discard the meat if it is past the expiration date, Seveau says.

What are the chances of getting listeria from deli meat?

Perhaps the most serious risk associated with eating unheated deli meat is the possibility of consuming meat that has been contaminated with listeria monocytogenes, the bacterium responsible for causing listeriosis infections, Seveau says.

While listeriosis infections are rare, they can pose deadly consequences, Seveau notes. The elderly, immunocompromised individuals, pregnant women and newborns are particularly vulnerable to experiencing the most serious side effects of listeriosis, she says. Almost everyone who develops listeriosis will require hospitalization, per the U.S. Centers for Disease Prevention and Control.

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While refrigeration will slow the growth of listeria on contaminated food items, it will not kill it, Seveau says. Accordingly, she underscores the importance of paying attention to recall notices on food items. If a food item that you have purchased, such as deli meat, has been added to a recall list due to listeria contamination, discard it immediately.