Raw and cooked onions add flavor and texture to many foods. Despite the urban legend that cut onions absorb harmful bacteria faster than other vegetables, the Nation Onion Association says they can be safely stored in the refrigerator when sealed in a plastic bag or container. An onion can go bad in many ways, from mold contamination to improper storage after cooking. To prevent illnesses, always discard spoiled onions without tasting them.
Pathogens and Produce
According to the U.S. Food and Drug Administration, a variety of harmful pathogens can infect fresh produce such as onions. Rinsing produce under fresh water before use is recommended, even if the item will be peeled, because harmful microorganisms such a Listeria, introduced from the soil, can contaminate cutting utensils and other equipment during food preparation. The effects of these pathogens range from mild to severe. Pregnant women, young children, the elderly and people with weak immune systems are most at risk of being hurt by spoiled onions.
Onions in Prepared Food
Failure to store prepared foods made with onions, such as potato salad, at or below 40 degrees Fahrenheit can result in food poisoning known as Clostridium. Symptoms begin 6 to 24 hours after consuming the food, and include cramps, nausea and diarrhea. If a food item made with onions, raw or cooked, has been left at room temperature for more than 2 hours – or more than 1 hour on a hot day above 90 F – throw the item out without tasting it. Bacteria begin to multiply rapidly, doubling in as little as 20 minutes when left out between 40 and 140 F.
Handling Fresh Onions
As with cooked food, a fresh cut onion grows bacteria more rapidly when left at room temperature than when refrigerated. Storing cut onions in the refrigerator stops the growth of harmful bacteria. Fresh produce such as onions that come in contact with animal or human fecal matter can cause Escherichia coli; symptoms such as cramping and vomiting usually begin within 3 to 4 days. Children under the age of 5 are at risk of developing kidney failure and should be seen by a doctor. To prevent E. coli, always rinse your produce in fresh water before consuming it. Using soap or special detergents is not recommended.
Facts on Onion Storage
As with all fresh produce, proper handling of onions before, during and after purchasing affects the storage life and safety of the product. Choose firm onions with even coloring and papery skin that are free of blemishes and mold. An onion contaminated with mold – even a small amount – should be discarded without using it, because mold spores penetrate and infect the whole vegetable. Store whole onions in a dark, ventilated place separately from potatoes; onions that absorb the gas and moisture from potatoes spoil more easily. When covered or wrapped, cut onions can be kept in the refrigerator for 7 to 10 days. Whole onions keep for up to 4 weeks when not exposed to moisture.
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