Do tomatoes lose flavor in the fridge?

Tomato flavor comes from sugars and acids you sense on your tongue, together with aroma compounds you sense through your nose. As you chew, aromas rise from your mouth into the back of your nose, and that completes what we know as "tomato flavor." That's why on a day when your nose is completely blocked, a tomato can taste like little more than sweet-and-sour water.

A tomato has to keep making these aroma compounds even after it's picked, because they slowly escape through the spot where the stem was attached. But tomatoes are a warm-climate crop, and below 12°C their production of new aroma slows down noticeably.

In 2016, researchers at the University of Florida and Zhejiang University in China stored ripe tomatoes at 5°C for 1, 3, or 7 days and compared them. The aroma compounds they examined numbered 66. After 1 or 3 days, aroma levels did not drop much, but after 7 days they fell clearly. Tomatoes kept cold for 8 straight days had 65% less aroma than on the day they were picked.

The 76 people in the taste test also liked the tomatoes chilled for a week less. Leaving them at room temperature for a day brought some aroma back, but even after three days it did not return to the original level. Meanwhile, the amounts of sugar and acid were the same before and after chilling.

A common misconception is that once a tomato goes into the fridge, its flavor is ruined. In the experiment, there was no major loss for up to about three days. Keep tomatoes you bring home at room temperature, and put them in the fridge only when they are so ripe they're about to turn soft. Even then, eat them within about three days and take them out a day before eating to limit the loss.

Unripe tomatoes are better left to ripen at room temperature. Cut tomatoes, however, spoil quickly, so they belong in the fridge right away. In that case, safety comes before aroma.