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Is it better to leave these tomatoes on the counter, or put them in the fridge? [Photographs: Daniel Gritzer]

Update: This article has been updated with further testing and even more information. Read the newer article here.

Is it better to store my tomatoes at room temperature or in the fridge?

Some people say that you should never refrigerate a tomato. Is this really true?

I've been told for so long, by so many people, not to refrigerate my tomatoes that I'm not sure if I've ever done anything other than leave them on my counter. But the question has made me think back on it, and to be honest, I can remember losing quite a few beautiful summer tomatoes over the years to rapid rot and decomposition because they were sitting out in sweltering heat.*

* Or, more accurately, I can remember losing parts of them, because I'd be damned if I was going to throw out an entire rotting, moldy, oozing, stinking tomato if there was even a sliver of good left to it. Remember: Tomato season is brief. Cherish it.

And I think this gets right to the core of the trouble with this rule: While refrigerators tend to operate within a narrow band of temperatures, usually in the 35-40°F zone, the actual temperature of most rooms can range anywhere from about 60 degrees to upwards of 100. Right now, for example, I'm typing this while sitting in my un-air conditioned Queens apartment, and I'd guess—based on the amount of sweat soaking from my lower back into my chair—that it's at least 90 degrees in here. Is 90 degrees really better for a tomato than 37 degrees?

To find out, I decided to run a little tomato-storage experiment of my own while visiting my mom down in Florida earlier this week.

My Quick and Somewhat Confounding Tomato-Storage Test

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To run my mini tomato experiment, I went out and bought three different varieties of tomato: first, run-of-the-mill hothouse tomatoes—you know, the kind that typically get sliced and served on cheap deli sandwiches; plum tomatoes; and finally some cherry tomatoes that came in a plastic clamshell and tried to look fancy by just barely holding onto their desiccated vine. (Nothing says farm-fresh like a withered, dried out stem.)

I bought several of each variety, selecting similar looking specimens to minimize variations in ripeness—fairly easy given that these were all pretty crappy yet highly invariable mass-market fruit. Sadly, while in Florida, I didn't have the opportunity to hunt down better quality tomatoes for this test. Still, in terms of relative quality, the cherry tomatoes were the best, the plums in the middle, and the standard ones the worst.

Once back at my mom's place, where the central air is set to about 75 to 80 degrees, I put half of each kind in the fridge, and the other half out on the counter.

After 1 Day of Storage

After letting the tomatoes sit in their respective environments for a day, I sat my mom and sister down and asked them to taste and rate my tomato samples, which I served to them blind. To make sure the cold of the refrigerator didn't sway their votes, I let the chilled tomatoes warm up to room temp before proceeding with the tasting.

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After 24 hours, the counter tomato, at left, was more red than its refrigerator counterpart.

Even before cutting into the tomatoes, I could see some differences. The standard tomatoes, for instance, had turned more red on the counter than they had in the fridge, though the difference was subtle.

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A close-up of the standard tomato skin: counter tomato at left, refrigerator tomato at right.

It can be hard to see, so here's an even closer shot of the two side-by-side. Note the yellow flecks on the skin of the refrigerator tomato on the right, as compared to the redder skin of the countertop tomato on the left.

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The room-temp plum tomatoes (left) also ripened faster than the refrigerated samples, as seen by the more red color.

The plum tomatoes showed a similar effect, with the countertop ones (at left in the photo above) more red than the chilled ones to the right. The cherry tomatoes, meanwhile, were harder to tell apart by sight.

Once I cut into them, a similar pattern emerged:

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Here the refrigerated sample is to the left, with a slightly lighter, less red color, though the difference is just barely visible.

Inside, the standard tomato looked slightly more yellow and pale in the refrigerated sample than the countertop one, though both looked mealy and not particularly ripe.

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Refrigerated plum tomato, left, and countertop at right.

The plum tomato showed the most drastic visual difference, with the refrigerated sample appearing more white and grainy in its flesh than the countertop one.

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Here's an even closer look at the plum tomato, again with the refrigerated sample to the left.

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Cherry tomato

The cherry tomatoes showed the least difference, with a just barely perceptible increase in redness in the countertop sample (left).

As for the taste test results? Well, first my mom was disqualified because she kept rejecting all the tomatoes, regardless of storage method, while reminiscing about what they used to taste like in the farmlands of Maryland where she grew up in the 40's and 50's.

My sister, thankfully, was able to focus on the task at hand—analyzing the relative, not absolute, merits of these tomatoes—and give me her opinion. In each case, the tomato she picked as her favorite was the countertop sample: Not once did the refrigerator sample come out on top. She found the countertop ones to be more aromatic and sweet, with a better texture than the refrigerated ones, though she said the differences weren't as apparent with the cherry tomatoes.

My own tasting of the samples backed her choices up, and she and I walked away with a few key conclusions:

  • First, a truly mediocre tomato, like the standard ones here, cannot be turned into a good tomato, no matter how you store it.
  • A tomato that is just fine but not great, like the plums I had bought, can benefit quite a bit from being left out at room temp.
  • Better-tasting tomatoes, like the cherries in this test, aren't as adversely affected by cold temperatures.
  • Another detail that my sister pointed out: Tomatoes with more flesh and less seed-jelly, like the standard ones here, are more likely to suffer textural degradation than varieties with very little flesh and more seed-jelly, like the cherries.

So far, my test was running as I'd expected.

The Inexplicable Case of My Tomatoes After 2 Days of Storage

It was at this point that I thought I'd repeat my tasting after another day, confirm all my findings, and be done with it. So a day later I sat my family down, this time my sister, stepfather, and mother (whom I explained could only participate if she forgot about those mythic Maryland tomatoes and focused on the ones in front of her).

Once again, I let the refrigerated tomatoes warm up to room temperature before serving them alongside the countertop ones. But this time, I also stuck some of my countertop ones in the fridge a couple hours earlier, to compare chilled countertop ones to chilled multi-day refrigerated ones. I served all the tomato samples blind.

And the weirdest thing happened: First, my mom's and stepfather's results were all over the place. If my mom picked one as her favorite, my stepfather picked the other. But more critically, my sister reversed all her picks from the day before, and consistently selected the refrigerated tomatoes as her favorite this time. What?

Confused, I sat down at the table and asked my sister to serve me the samples blind. Here's what's even more weird: Because I had been slicing, smelling, and tasting the tomatoes as I served them, I was able to correctly differentiate the refrigerated and countertop samples every time by smell alone, but even though I could tell them apart, I had to agree with my sister—the refrigerated ones were better today, in all cases.

For whatever reason, in the case of these three types of tomatoes, the refrigerator initially made them worse, but with extra time they became better than the countertop ones.

Conclusions

One thought about my test results is that, because my mom's home was a warm-ish 75-80°F, the heat started to take its toll on my countertop samples once enough time had elapsed.

As I've reviewed some tomato literature, this explanation starts to make some sense, though I haven't verified that it's correct. What most studies have found is that storage temperatures can affect both a tomato's texture and volatile aromatics (which are responsible for its complex scent), with colder temperatures degrading the volatiles more quickly.

According to this report from the Department of Plant Sciences at UC Davis, firm ripe tomatoes are best held anywhere from 44-50 degrees, which is higher than fridge temperature but lower than most rooms (they say to store less ripe tomatoes at higher temperatures, which supports my above observation that riper tomatoes can withstand the cold, while less ripe ones benefit from some warmth). This French study, meanwhile, found that 4°C (39.2°F) temperatures are much more harmful to volatiles in the tomato than 20°C (68°F), though they also found that letting refrigerated tomatoes sit out for 24 hours at 68 degrees reversed some of the ill effects.

But what all the studies I've seen fail to explore is the effect of even higher temperatures on tomato storage. That may not be a problem for tomato and produce companies with refrigerated trucks and warehouses, but it is a problem for those of us at home, since not all with air-conditioning have the thermostat set as low as 68°F or even have it running 24/7, and some of us, like myself, don't have air-conditioning at all. Given that tomatoes ripen in the summer, the challenge is that we're trying to store them at home during a season characterized by intense heat, and we don't usually have storage conditions in the 44-50 degree range.

Which is all to say that I don't think there's an easy answer here. After these tests and my research, though, I can say that I no longer believe that the rule of never refrigerating tomatoes is a reliable one: there are far too many variables. The best advice I can give right now is to consider the temperature of your environment, the quality of your tomatoes, and how long you're hoping to keep them. Bad (i.e., under-ripe) tomatoes will benefit from being left out on the counter at least for a short period, though take care if your kitchen is warmer than 70 degrees as they may not do as well after a couple days; at a certain point you may be better off moving them to the fridge. Ripe tomatoes, meanwhile, are fine on the counter for several hours, but I'm starting to think, based on my results, that the refrigerator may be worth considering for holding them much longer than that—even if it does kill some of the volatiles, at least they won't rot before you eat them.

Update: This article has been updated with further testing and even more information. Read the newer article here.

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