With Certain Types Of Produce, Refrigeration Isn't Cool

January 17, 1998

UNIVERSITY PARK, Pa. -- In the modern American kitchen, the refrigerator is where consumers store most of their produce. But not every food item can chill, say two produce specialists in Penn State's College of Agricultural Sciences.

"Anything that ripens after it's harvested shouldn't be put in the refrigerator," says Peter Ferretti, professor of vegetable crops. "That includes tomatoes, unripe pears and all melons except watermelon. Chilling temperatures below 55 degrees Fahrenheit retard ripening."

Tomatoes. Ferretti says a tomato will lose its aroma and flavor after just 40 minutes in the refrigerator. He recommends storing tomatoes in a warm, dry area. Vine-ripened tomatoes can be stored this way for up to two weeks. "Depending on how fast you want them to ripen, store tomatoes on a counter or on top of the refrigerator, out of sunlight," suggests Kathleen Brown, associate professor of post harvest physiology. "The warmer temperatures on top of a refrigerator will make a tomato ripen faster." Ferretti recommends storing tomatoes so none are touching, especially if the produce has cracks or lesions. "The idea of one rotten apple spoiling the whole bunch applies here," he says. "The best place to store tomatoes is in an aerated basket that allows plenty of air flow."

Cucumbers. While sensitive to cold, cucumbers must be refrigerated because they lose moisture rapidly even when they are lightly waxed. Prolonged exposure to cold, however gives cucumbers pitted, mushy spots. Eggplant is affected in similar fashion. Ferretti recommends storing them in a paper bag in the refrigerator crisper drawer.

Potatoes and sweet potatoes. When potatoes are refrigerated, their starch turns to sugar, Ferretti explains. While this condition can be reversed by removing the potatoes from the refrigerator, they will still retain some sugar, which causes them to brown when fried. "Potatoes should be kept in a dark place slightly cooler than the normal temperature of the home, such as in a cool cupboard, in the basement wine cellar or storage area, or near the inside wall in a garage," he says. "In extremely cold conditions, covering the potatoes with a blanket or burlap will provide protection."

Tropical fruits. Any tropical fruit, such as bananas, mangos, papayas and others, should never be refrigerated. "Only chill bananas if you don't want them to ripen anymore. The skins also will nearly turn black--the inside flesh can still be a normal white. They can also be chilled or even frozen prior to cooking or for a special popsicle-like dessert," Ferretti says.

Citrus fruits. For oranges, lemons, limes and grapefruit, refrigeration is a good way to preserve quality. "Citrus fruits do not ripen further after harvest," Brown says.

Winter squash or melons. Ferretti says winter squash should only be refrigerated after cooking, and melons should be refrigerated only after being cutopen. "These items maintain their best aroma and flavor at room temperature," he says.

When storing produce, Ferretti says, make liberal use of the crisper drawers. In most recently manufactured refrigerators, the crisper drawers can be somewhat adjusted for temperature and humidity. "The crispers are usually marked 'fruits' or 'vegetables' or 'cool' and 'moist.'" He also recommends storing fruits and vegetables in paper or plastic bags with holes to slightly increase temperature and humidity.

"Fruits and vegetables should never be stored against the back wall of a refrigerator," Ferretti warns. "The rear wall is the coldest area of any refrigerator and chilling injury or light freezing may occur."

If produce becomes frozen, Ferretti recommends handling the produce carefully. "When a celery or cabbage is frozen, the cells are particularly sensitive to touch. Damage and bruising will occur unless they are allowed to thaw slowly with very little handling," he says.

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EDITORS: For more information, contact Peter Ferretti at 814-863-2313 or John Wall John_Wall@agcs.cas.psu.edu 814-863-2719 814-865-1068 fax

Last Updated March 19, 2009