At Serious Eats, we take the science of food storage—wait for it—seriously. I remember reading Kenji’s tomato storage article back in 2017 and immediately flipping all my tomatoes over, chastising my then-boyfriend for thinking I’d had a very strange momentary lapse of produce storing judgment. Daniel’s bread refrigeration piece changes lives regularly, per the feedback in our SE staff email inbox. And Genevieve’s deep-dive into the steps necessary to preserve strawberries remains a perennial top performer for the site, even in months it makes no sense to eat strawberries! 

So it stands to reason I’d take the official Serious Eats blueberry version of those experiments very—wait for it—seriously! And I did! If I wanted to determine the absolute best way to store blueberries for longevity, freshness, and flavor, I would have to be meticulous. Like, now-husband-rightfully-thinking-I’d-lost-my-whole-mind-re: produce meticulous!!

After a deep-dive into existing blueberry storage literature, a cross-reference of my green bean and cherry tests from last year, and a look into all mentions of produce storage on Serious Eats, I identified and set up a series of tests to determine the best way to store blueberries. I tested 18 different methods, including ones that supported existing theories about the best way to store blueberries, as well as those that directly opposed agreed upon methods. In addition to challenging accepted methods from the world outside of Serious Eats, I also put berry storage methods from the Serious Eats canon to the test to see if what worked for, say, strawberries, also worked for blueberries. The! Results! Will! Shock! You!

What We Know About Blueberries (and Blueberry Storage)

Blueberries are “true berries” in that they are fruits that come from the ovary of a single flower and have their seeds embedded inside their flesh. By this definition, strawberries and raspberries are not berries, but instead are aggregate fruits, which come from several carpels of the same flower. Blueberries have thicker skins than those aggregate fruits, and they have higher levels of anthocyanins—the water-soluble pigment responsible for the fruits’ color—than juuust about any other “berry” (elderberries and mulberries being the exceptions). 

A September 2014 Postharvest Biology and Technology study confirms that the most salient factor leading to blueberry demise (see: shriveled or burst fruit due to moisture loss) is temperature. The higher the temperature, the more accelerated the fruits’ metabolism. The higher the metabolic rate that occurs, the likelier it is that blueberries will lose moisture and begin to break down.

The Tests

Considering all the above, I strongly suspected that a  good chunk of the berries I tested, including the blueberries left at room temperature, wouldn’t yield the greatest results. 

I first removed all the berries from the package and picked through them to remove any bad berries from the batch. Then I divided them into batches and proceeded with the tests outlined below.

• Unrinsed blueberries in their original packaging at room temperature
• Rinsed blueberries in their original packaging at room temperature
• Unrinsed blueberries in their original packaging in the fridge
• Rinsed blueberries in their original packaging in the fridge
• Unrinsed blueberries in their original packaging in the crisper
• Rinsed blueberries in their original packaging in the crisper
• Unrinsed blueberries in a shallow bowl in the fridge
• Rinsed blueberries in a shallow bowl in the fridge
• Unrinsed blueberries in a shallow bowl in the crisper
• Rinsed blueberries in a shallow bowl in the crisper
• Blueberries soaked in a vinegar bath, then rinsed, then dried in a shallow bowl in the fridge
• Blueberries soaked in a vinegar bath, then rinsed, then dried in a shallow bowl in the crisper
• Unrinsed blueberries in an airtight container in the fridge
• Rinsed blueberries in an airtight container in the fridge
• Unrinsed blueberries in an airtight container in the crisper
• Unrinsed blueberries in an airtight container in the crisper (just for fun, really)
• Blueberries washed in hot (125°F) water, drained, dried delicately but completely in a salad spinner triple-lined with paper towels, placed back in their original container, and stored on a shelf in the fridge.

The two tests I was most confident in were the third and the last ones listed above. The third—unrinsed blueberries stored in their original packaging in the refrigerator —most logically follows all existing blueberry guidance. The latter—rinsing in hot water, drying thoroughly, and storing in the fridge— is exactly Genevieve’s proven strawberry storage winner, as it is Kenji’s before her and Harold McGee’s before him. The idea behind this hot water application (as opposed to just leaving the berries alone) is that you can ward off mold and extend their shelf lives.

The Results

In my first batch of tests, the unwashed blueberries thrown in the fridge went a full nine days before I noticed any sign of decay or mold. They’d barely lost weight at that point too. Honestly, I would’ve fed them to my toddler up until about day 11. Conversely, my hot water-washed berries felt soft nearly immediately after their bath. I gave them until day four (and a ~16% drop in mass) before giving up on them completely. It’s worth noting Kenji doesn’t specify this technique is most appropriate for blueberries in his original produce-washing investigation. He tested it on blackberries, raspberries, and strawberries (all of which are aggregate fruits, I should add? Maybe!?). 

After my tests were complete, Genevieve and Daniel ran follow-up tests of my winning storage method—the unwashed, original packaging one—against the hot water method. Genevieve had similar results to mine; Daniel, who was testing on beautiful farmers market berries, found no difference in batches across many days (he ultimately had to cut his tests short for PTO reasons).

Genevieve, Daniel, and I have run theories about anthocyanins and water solubility back and forth for weeks since then. Are these hyper-pigmented fruits a bad idea to wash because you’re actively ruining them in the process? We know the stability of anthocyanins are also impacted by temperature. Is that why the hot water bluebs fared much more poorly than my room temp-rinsed ones, which, on average lasted about six days before mold sightings!? Or maybe Daniel had a different variety of blueberry! Maybe his were just fresher than mine and Genevieve’s! Maybe when you’re not dealing with freshest blueberry—even if it looks good!—you’re dealing with enough deterioration on a microscopic level that the hot water rinse just ruins everything. 

I spoke to Professor Penelope Perkins-Veazie, who is cited repeatedly in the first study linked above here, via email, and she noted: “Anthocyanins are generally regarded as highly water soluble (around 80%), but because blueberries are quite complex in anthocyanins and other flavonoids, I don’t know if the [two are related]. As far as longevity, such as storage life, I’m pretty sure that there has been no work to look specifically at the shelf life and amount of anthocyanin in blueberry.”

Conclusions: How to Store Blueberries So They Last Longer

All this to say: The easiest way to ensure you’ll have fresher blueberries for longer is to get them into the fridge exactly as you bought them as quickly as possible. (Worth mentioning: My countertop blueberries went to hell in literally four hours on an East Coast morning in July.) But if you’re looking to feel better about mold spores and don’t need to keep your blueberries around for the week, go ahead and give them a hot rinse and a thorough dry. To recap, here’s the simplest and best way to store blueberries:

• Remove any moldy berries from original packaging.
• Store remaining blueberries (in that same packaging) in the fridge. (If your blueberries come in a cardboard carton and that carton becomes damp, you should transfer the berries to a clean, dry container after removing any moldy berries.)
• Rinse well right before consuming.