Wait, Is It Safe To Eat That Expired Yogurt?

Let’s be honest, groceries are expensive these days, and with rising food costs, we’re even more aware of the looming best-by dates dotting some of our favorite drinks, snacks, and staples. So, as much as I love fresh produce and minimally processed foods, I’m also a big fan of fermented foods, due in large part to their extended shelf life. 

But what happens when those pesky best-by dates come and go and your fermented faves still look (and smell), well, totally edible? I chatted with a few food experts to get the scoop on when to toss that container of shredded parmesan that's been calcifying for just a bit too long, and when that pickle jar's best-by date can be fudged just a little.

But first: what are fermented foods?

Newsflash: Kombucha isn’t the only fermented food on the market—it’s just the buzziest bev category to be labeled with the moniker. In reality, some of your go-to grocery items like yogurt, cheese, wine, and beer are all fermented, and other popular picks like pickles, hot sauce, and charcuterie meats are, as well. 

“Fermented foods are nature’s original preservation method,” says food scientist and TED Talk speaker Dr. Vincent Candrawinata, PhD. “Many people think it is just a ‘trendy’ way of food processing, but long before refrigerators, fermentation was used to make foods last; through fermentation, good bacteria, yeasts, or enzymes convert sugars into acids or alcohols, creating an environment that’s naturally more stable and less friendly to harmful microbes.”

While fermented foods naturally have a longer shelf life when housed unopened in the original packaging, once opened, the food’s microbiome shifts and stability is compromised with each use. Air, warmth, and bacteria from hands and utensils are then introduced. “That’s why guidelines like ‘Use within 3 to 5 days of opening’ are included,” Dr. Candrawinata points out.

Still, how do you know if you can eat expired, unopened yogurt? Or that delectable wedge of syrah-soaked toscano cheese from Trader Joe’s that you forgot was in the back of your fridge? The first step is understanding the difference between best-by and expiration dates. 

What do food labeling dates mean?

Once upon a time, expiration dates were the only labels on food. Nowadays, we have best-by, sell-by, use-by, and freeze-by dates, as well. So…which one should you actually follow, to the extent of tossing if you’re beyond it?

According to food scientist Abbey Thiel, PhD, most food labeling dates indicate quality, not safety. “For example, a best-by date doesn't mean the food is unsafe to eat after this date; the best-by date is set by the company so that you eat their product while it's still at its maximum quality,” she says. “They do this because they want customers to come back and buy their product again and again.”

Thiel clarifies what the other top three food-dating methods—none of which are related to food safety—seen in grocery stores across the U.S. 

• Sell By: Helps a store determine how long the product should be displayed and aids in inventory management.
• Use By: Recommendation for when to use the product by to ensure optimal taste and texture.
• Freeze By: Recommendation for when to freeze the item to maintain optimal taste and texture. 

What’s important to remember is that these quality dates are not required by law, and do not depict when a food is still perfectly safe to consume. “The one exception is infant formula, which must be dated,” Thiel points out, noting that it typically falls under the use-by category.

But what about expiration dates?

More often than not, modern-day foods are labeled with one of the four aforementioned labels: Bbest by, sell by, use by, or freeze by. Some foods, however, do have actual expiration dates. 

“Expiration means the product may no longer be safe to consume after that date,” Dr. Candrawinata says. “You’ll usually only see this on things like infant formula, certain medications, or highly perishable goods.”

How to tell if your fermented foods have gone bad

We have our five senses for a reason: They allow us to enjoy life to the fullest while also enabling us to protect ourselves against potential threats, expired food included. 

Thiel usually guides people to use their senses. “Smell the food; is there a foul smell, or does it smell like normal,” she says. “Or, do a visual examination of the food: Do you see any microbial growth, or does everything still look good?” In general, Thiel says that spoiled food typically has an off-odor, off-flavor, or abnormal texture due to the growth of spoilage microorganisms. If none of those things are present, proceed as you see fit. 

Keep reading for further guidance on when to toss your favorite fermented foods, and when it’s a-ok to keep enjoying them beyond the best-by date. 

Yogurt

• Beyond the best-by date: “When stored in the fridge at or below 40°F, [unopened] yogurt stays fresh for one to two weeks past the best-by date,” certified food scientist Jessica Gavin reveals. If the yogurt has been opened, registered dietitian and Chelsea Nutrition founder, Jennifer Maeng, MS, RD, LD, CDN, says it can usually be consumed within five to seven days, so long as proper food handling practices have been used (ie: Not eating directly out of the container, introducing saliva into the yogurt). “Greek yogurt, with less moisture content, often stays fresh longer than regular varieties,” she adds.

• The test: Take note of any weird smells. “Sniff it first, as it should have a sour, tangy smell,” Thiel says. “If instead, it smells putrid, yeasty, or rotten, then toss it out.” Additionally, Thiel says to do a visual check for mold. “I’ll check the lid or surface of yogurt for mold growth; mold typically needs oxygen to grow, so you'll spot it here,” she explains.

Cheese

• Beyond the best-by date: It depends on the type of cheese. “I am more careful with the softer varieties—cream cheese, queso fresco, Brie, fresh mozzarella, etc; these have more water content and so can support microbes more readily than harder varieties,” says Consumer Federation of America director of food policy, Thomas Gremillion. “For a cheddar or parmesan, I think it's fine to cut off the mold and eat what’s left as the occasion demands, but the softer varieties are more prone to Listeria monocytogenes, and more relevant to rules of thumb like the four-hour rule.” 

Some other factors Gremillion looks for include the temperature the cheese was stored at, if it’s newly opened, if it’s been sitting on a charcuterie board being exposed to air and hands. 

Overall, Gavin says that hard cheeses, like cheddar or parmesan, last up to six months unopened and three to four weeks once opened. “Soft cheeses like Brie or goat should be used within one to two weeks, and shredded and sliced processed cheeses typically last about a month,” she adds.

• The test: Zoom in on appearance. “For soft cheese, a slimy texture or discoloration is a key sign to throw it out,” Thiel says. “For harder cheese, give a visual test for mold growth…stay away from anything that has drastically changed texture, has excessive moisture, or smells off.”

Pickles

• Beyond the best-by date: According to Maeng, unopened commercial pickles can last for one to two years beyond their best-by date, while opened jars should be kept refrigerated and consumed within one to three months. 

“Properly fermented pickles in brine with sufficient acidity (pH below 4.6) can last more than six months after opening when refrigerated,” she adds. “Pickles preserved in vinegar typically last longer than traditionally fermented varieties due to higher acidity.”

• The test: Take a closer look. “Look for white, fuzzy mold floating near the top of the jar,” Thiel says. “Anything that smells funky, should be tossed.” Thiel also notes that anything slimy or disintegrating should go too.

Hot sauce

• Beyond the best-by date: “Acid plus salt equals a long [shelf] life,” Dr. Candrawinata says. “Most hot sauces, especially vinegar-based ones, can last years—yes, years—if stored correctly.” While hot sauce doesn’t have to be refrigerated, Gavin says that it will stay fresher, longer in the fridge. 

• The test: Use your senses. “Hot sauce should be very shelf stable, especially if it's vinegar-based, but the usual tests apply,” Thiel assures. “You want to stay away from any hot sauce that smells weird, tastes off, or has visual microbial growth.”

Charcuterie meats

• Beyond the best-by date: Proceed with caution. “Even with perfect food handling practices, these products may pose an unreasonable risk of Listeria monocytogenes infection to some vulnerable individuals, like pregnant women and immunocompromised people,” Gremillion says. “This is one class of products where I would interpret the best-by or use-by date as an actual expiration date.” 

Additionally, Gremillion says to be careful about consuming charcuterie meats that have been left out on a grazing board for hours on end. “Experts advise against eating charcuterie left out unrefrigerated for more than two hours, and for using sealed containers when storing open charcuterie in the fridge,” he shares.

• The test: Give it a whiff. “These meats have several factors that should deter microbial growth, including added salt, fermentation, drying, and smoke, but if there's an unusual smell or visual appearance, it should be tossed,” Thiel says.

Wine and beer

• Beyond the best-by date: Give it a sniff and a sip. “Unopened white wine lasts one to two years, and red wine three to five years when stored in a cool, dark place,” Gavin says. “After opening, both should be refrigerated and used within one to three days.” 

Meanwhile, Gavin says that unopened beer lasts up to nine months in the pantry. “Once opened, drink it within a day and keep it refrigerated,” she instructs.

• The test: Take a sniff. “If wine smells like vinegar, this is a sign that acetic acid bacteria have accidentally taken over,” Thiel says. “If beer or wine has a sour or strange taste, it's probably infected by a wild bacteria or yeast and not a good idea to drink.” 

It won’t necessarily make you sick, though. “Wine and beer won’t spoil, but it might not taste great,” Dr. Candrawinata says. “Wine may become oxidized or ‘corked,’ while beer past its prime might taste flat or weird.” He adds that they’re rarely unsafe, but “just less enjoyable.”

Kombucha

• Beyond the best-by date: According to Maeng, unopened kombucha can last up to three months beyond the printed best-by date. Once opened, however, it should be consumed within seven to 10 days. “Kombucha continues to ferment slowly even when refrigerated, which means it may become increasingly acidic and carbonated over time—not necessarily unsafe, but the flavor profile will change,” she adds.

• The test: You know the drill: Take a whiff. “Bad news if it smells like garbage, cheese, or rotten eggs,” Thiel says. “Check near the cap for any fuzzy, mold growth, too.”

The takeaway

Can you eat expired yogurt? It depends. If it looks, smells, and tastes fine, you should be fine—and that goes for most fermented foods. 

“It's not really necessary to toss a fermented food if there's no visible sign of spoilage,” says food scientist and food safety expert, Dr. Bryan Quoc Le, PhD, of Mendocino Food Consulting. “Best-by dates are for optimal quality that maximizes the consumer experience and helps the company's brand, but they are not dates for when the food has suffered from a pathogen contamination.” 

When concerned about food safety, Quoc Le says to determine if your food has a best-by or use-by date, or a true expiration date. “An expiration date is more likely to be a function of food safety, but even here it is up to the food company to decide if the expiration date is where the food has suffered so much spoilage and oxidation that it's not rendered edible from a sensory perspective, but is still technically safe to eat.”

All in all, Maeng says to use your senses. “With most fermented foods, the dates on packaging represent quality milestones rather than safety cutoffs, so your senses are often the best tools for determining whether these foods remain good to eat,” she says. “When in doubt, throw it out.”