Study: Fridge damages tomatoes

An international group of horticulturalists’ study in the Proceedings of the National Academy of Sciences looks at the effects of refrigeration on flavor compounds in tomatoes.

A sentence from the PNAS news release about the study stands out: “Chilling fruits at temperatures below 12 degrees Celsius (or about 53 degrees Fahrenheit) hampers enzymes that help synthesize flavor-imparting volatile compounds, resulting in relatively fresh but insipid fruits.”

The researchers, led by horticulturalist Bo Zhang of the University of Florida, argue that the problem stems not from the tomatoes but from the postharvest practice of chilling fruit. Keeping tomatoes at low temperatures slows the ripening process and prevents them from rotting, but it also interferes with chemical compounds that give tomatoes taste.

Flavor in a fruit is determined by three things: sugars, acids and “volatiles,” the chemical compounds that are largely responsible for its aroma. Sugars and acids aren’t affected much by refrigeration, but most volatiles are synthesized during ripening, which is part of the reason ripe fruit has such a strong smell.

Researchers collected heirloom and ordinary store varieties and stuck them in a 41-degree-Fahrenheit fridge for one, three or seven days. Each tomato then got a one- or three-day “recovery” period at room temperature. The shorter periods of refrigeration didn’t have much impact on volatile content, but seven days significantly depleted them, and neither of the recovery periods seemed to bring them back.