Subtitles section Play video Print subtitles You may have been told that putting tomatoes in your fridge will ruin them. It turns out, that's kind of true. Scientists have shown that reducing a tomato's temperature to below 20°C alters its gene expression, which in turn reduces its yummy tomato smell. So putting tomatoes in the fridge actually does make a lot of their ripe, juicy flavor disappear! You might think a food's flavor is determined by the specific mix of chemicals that lands on your tongue. And it is… partially. But by definition, flavor is the overall impression you get from consuming a food or beverage, an impression which results from both taste and smells. There are only a handful of distinctive tastes that your taste buds can differentiate: sweet, salty, sour, bitter, and umami. Scents, on the other hand, are practically limitless. Some research suggests the average person's nose can distinguish between one trillion different odors, and all that variety could explain why scent is the largest determinant of flavor. It's like when you were a kid and your parents made you eat something you didn't like, and you would hold your nose while you downed it. Plugging your nose and blocking the smell of something is actually enough to seriously diminish the flavor because flavor is so reliant on smell. Which brings us back to those tomatoes. A tomato's flavor is the result of a combination of tasty sugars and acids, as well as chemicals called aroma compounds, the molecules that easily leap into the air to give things their distinct smell. And even after picking, the fruit continues to make some of these and break down others. It's still full of living cells, so the overall flavor of the tomato can change over time. In a 2016 study, when researchers put ripe tomatoes in the fridge for 7 days, volunteers rated the taste of those chilled tomatoes as much less yummy than fresh ones. But the sugar and acid levels, those key components of taste, didn't differ between the fresh and chilled fruits. What did change were those aroma compounds: refrigerated tomatoes produced 65% less of them. That led the team to conclude that the change in the tomato's flavor is caused by a reduction in its odor molecules, not due to a change in its actual taste! When they dug deeper, they found that the refrigerated tomatoes had reduced expression of genes related to the synthesis of certain molecules, including branched amino acids, fatty acids and esters, three key compounds that are important for aroma compound synthesis. The researchers hypothesized that this could be an evolutionary response for conserving energy when it is cold, though they'd need further evidence to confirm that idea. It's not just tomatoes that are ruined by refrigeration, of course. You might have noticed that a lot of different fruits seem to taste worse after a stint in the fridge, but this is generally thought to be because lower temperatures halt the ripening process. As a fruit ripens, it produces different aroma compounds, and it gains sugars and other tasty molecules. So the less ripe a fruit is, the less yummy it will be. But if you take these fruits out of the fridge and put them on the counter, they will start ripening again and recover most of their flavor. And once they're ripe, you're supposed to be able to put them back into the cold to keep them at that tasty sweet point for longer. But the researchers in this study weren't starting with under-ripe tomatoes— they were starting with ripe ones. So the loss of flavor wasn't because they prevented them from becoming fully ripe. And taking the tomatoes out of the fridge didn't fully fix things. So basically, there's no point in a tomato's ripening process where you can refrigerate them without losing flavor. It's possible, or even likely, this kind of cold-induced flavor loss happens in other ripe fruits, too. But as of yet, no one has really looked. Either way, if you want the best-tasting produce, you should probably leave your fruits on the counter until they are ripe, and never ever put your tomatoes in the fridge. Though, if you really want the tastiest tomatoes, you should probably go for more colorful ones, because the rosiest red tomatoes you see in stores just don't taste as good. Check out our episode on Why Tomatoes Are So Bland to find out why! And as always, thanks for watching, and don't forget to subscribe!