Typically, more delicate berries like blackberries and raspberries last three to five days, while heartier berries like blueberries and strawberries stay fresh between five to seven days. To help you avoid ever having to throw away a carton of moldy berries again, we’ve compiled a few simple tips and tricks that can prolong their shelf life by keeping them fresh for longer. Read on to learn the very best ways to get the most out of your season’s pickings—sweet, ripe, and mold-free—plus the science behind why berries get moldy so fast.
Why do berries spoil so quickly?
Berries tend to spoil quickly due to mold spores that they carry on their surface. According to the U.S. Department of Agriculture (USDA), mold spores are microscopic fungi that live on plant and/or animal matter. The USDA notes that though it’s unclear exactly how many mold species exist, there are likely more than 300,000 different kinds. These microscopic organisms can easily spread from plant to plant, blowing across the air, which makes them difficult to control or avoid when farming.
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Plump berry varieties like strawberries (which are approximately 92 percent water) tend to lose moisture rapidly once picked, which further adds to the mold potential. This is because water loss causes berries to wilt, and the moisture that leaches out in the process makes for a more humid storage environment, resulting in quicker mold growth and spoilage.
Though most mold prefers warmer environments, the USDA says that it can also grow at refrigerator temperatures. To best avoid mold at home, they recommend cleaning the inside of your refrigerator frequently with a baking soda solution and keeping humidity levels below 40 percent.
How to store berries: 4 ways to keep your berries from getting moldy
1. Line your container with paper towels.
“The best way to keep your berries fresh is to line their storage container top and bottom with a paper towel,” says farmer Kenny Tanaka of Tanaka Farms, a 30-acre fruit and vegetable farm nestled in the heart of Irvine, California. He recommends placing the berries inside and then covering them with another layer of paper towels before closing the lid.
Tanaka also strongly emphasizes that it is best not to wash the berries until you’re ready to eat them. “Moisture will make the berries spoil, which is why this method is so effective—the paper towel will help absorb some of the moisture,” he explains. As the berries release moisture naturally and the condensation begins to accumulate within the container, the paper towels will help absorb the excess humidity, reducing the risk of mold growth and rot.
2. Soak berries in a vinegar solution to remove mold and bacteria.
If you’re looking to get your meal prep for the week done at once and waiting to wash your berries doesn’t work for you, a vinegar-based soak might do the trick. In a large bowl, combine four cups of water with one cup of white vinegar. Submerge the berries for a few seconds, drain in a colander, and rinse them under cool running water. Then, use a salad spinner to gently wick away the moisture and remove as much excess liquid as possible. Finally, pat them until completely dry with paper towels and place them in a paper towel-lined container with a loosely-fitted lid.
A natural antifungal and antibacterial, vinegar helps stop the growth of mold, fungi, and other microorganisms, which can potentially help prolong the shelf life of berries for upwards of two weeks. Though this method requires a few extra steps, it’ll be worth the effort when your berries taste freshly-picked for far longer than usual.
3. Give your berries a quick hot water bath.
Before you run to the store because you used the last bit of vinegar in the pantry, know that a hot water bath can also be an effective method for preventing moldy berries. Heat a large pot of water, and just before it begins to simmer, check the temperature using a thermometer until it reads between 125°F and 140°F. (Note: this is *not* boiling temp—we’re not trying to make jam). Then, quickly dunk the berries for about 30 seconds. Carefully remove them from the water, thoroughly dry them, and store them in a paper towel-lined container.
Though this trick may not be as effective as a vinegar-based solution, it may help reduce mold growth and prolong the freshness of the berries for a few days. To maximize the results, always make sure that the berries have been thoroughly dried before stashing away.
4. Pick the freshest berries possible at the market, and get rid of any bad ones immediately.
Although this may seem obvious, choosing the best batch of berries available can help with the longevity of the bunch. Take a careful look at the selection, and avoid any berries that show signs of wilting, bruising, or decaying. Once home, sort through them, and discard any that have started to spoil. Next, carefully store the healthy berries in a towel-lined container, making sure to avoid overcrowding them.
Pro tip: if your berries look like they’re about to turn before you’ve had a chance to enjoy them, consider freezing them. They’ll still taste delicious in smoothies, baked goods, or oatmeal—fresh, nutrient-packed, and (most importantly) free from mold.
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