Tomatoes officially taste worse when they’ve been refrigerated, thanks to a new study revealing how certain genes that produce flavor are downregulated as a result of chilling. This explains why commercial tomatoes – which are normally chilled in order to delay ripening and prevent decay – are considered by many to be less delicious than those bought directly from farmers.

The flavor of a tomato is produced by a combination of sugars, acids and volatiles, which are amino acids and esters that have a particular taste. Previous studies have shown that some of these volatiles are lost when tomatoes are stored at low temperature, prompting a team of international researchers to try and figure out why this happens at the molecular level

By storing tomatoes at 5 degrees Celsius (40 degrees Fahrenheit) for a period of 8 days and then analyzing the changes in expression of 25,879 genes, the researchers were able to determine how low temperatures affect the regulation of genes that code for flavor-producing volatiles.

Their results, which appear in the Proceedings of the National Academy of Sciences, reveal that genes controlling the production of 12 different volatiles were downregulated after being refrigerated. This was later verified by a taste test, in which a group of 76 consumers identified these tomatoes as being less flavorsome than others that had not been refrigerated.

Even when later placed in a warmer environment, the expression of these genes did not return to normal, revealing how chilling tomatoes permanently robs them of their taste.

However, tomatoes that were refrigerated for up to three days did not display any epigenetic changes, suggesting that they can be kept at low temperatures for a certain period of time before they become ruined.

The research also revealed that sugar levels are not affected by refrigeration, so sweet tomato-based products like Ketchup are unlikely to lose any flavor in the fridge.