Finally, science explains why you shouldn't put tomatoes in the fridge

NEW YORK  If you buy tomatoes from John Banscher at his farmstand in New Jersey, he’ll recommend keeping them out of the fridge or they’ll lose some of their taste.

Now scientists have figured out why: It’s because some of their genes chill out and are altered by cold temperatures, ultimately affecting the flavor. A new study unravels the process, and may someday help solve the problem.

Cooling tomatoes below 54 degrees stops them from making some of the substances that contribute to their taste, according to researchers who dug into the genetic roots of the problem.

That robs the fruit of flavor, whether it happens in a home refrigerator or in cold storage after harvest but before the produce reaches the grocery store shelf, they said.

With the new detailed knowledge of how that happens, “maybe we can breed tomatoes to change that,” said researcher Denise Tieman of the University of Florida in Gainesville.

She and colleagues there, in China and at Cornell University in Ithaca, New York, report their findings in a paper published Monday by the Proceedings of the National Academy of Sciences.

They showed that after seven days of storage at 39 degrees, tomatoes lost some of their supply of substances that produce their characteristic aroma, which is a key part of their flavor. Three days of sitting at room temperature didn’t remedy that, and a taste test by 76 people confirmed the chilled tomatoes weren’t as good as fresh fruit.

Tomatoes stored for just one or three days didn’t lose their aroma substances.

Further research showed that the prolonged chilling reduced the activity of certain genes that make those compounds, Tieman said.

To put it in technical terms, they write, “chilling-induced tomato flavor loss is associated with altered volatile synthesis and transient changes in DNA methylation.”

Methylation is the process by which a cluster of atoms known as a methyl group adheres to an organism’s DNA and alter its function. Methylation plays a role in regulating gene expression, and abnormal patterns of methylation have even been linked to the development of diseases. 

Her lab is already looking into the possibility of breeding tomatoes that don’t lose flavor in the cold, she said.

In the meantime, “Just leave them out on the counter, or leave them in a shaded area, something like that,” said Banscher, whose farm is in Gloucester County. “A tomato has a decent shelf life.”