Considering all the positives that onion has, what could possibly go wrong? It is believed that peeled onions shouldn't be stored or refrigerated.
According to Health Practitioner and Macrobiotic Health Coach Shilpa Arora, "Bacteria contaminate onions once exposed and if they are left as it is, they may get oxidized further leading to a host of health problems. It is advised to cut them only when you want to cook them." Nutritionist and Dietitian Parmeet Kaur agrees, "When you cut onions, the cell walls are disrupted; water and fluids are released, which may contain nutrients that promote bacteria growth. If you refrigerate peeled onions, the cold and humid temperature may make them soggy and lead to decay due to the combined process of bacteria growth and decay."
(Also Read: Are Onion Peels the Superfood of Tomorrow? You Shouldn't Discard Them)
Bacteria contaminate onions once exposed
How to ensure peeled onions are stored safely?
According to National Onion Association, never store peeled onions in plastic bags as the lack of air movement will reduce their storage life. The best way to store peeled onions is to wrap each onion in a paper towel and place them in refrigerator to keep them cool and dry. According to the United States Department of Agriculture (USDA), chopped or sliced onions can be stored in a sealed container in your refrigerator at the proper temperature of 40 degree Fahrenheit or 4.4 degree Celsius.
(Also read: Do Vegetables Lose Nutrients On Being Cut?)
never store peeled onions in plastic bags as the lack of air movement will reduce their storage life
So basically, peeled onions may be dangerous to store; try and peel them when required. It is always better to be cautious in case of cut vegetables. Go ahead and use this precious ingredient and extract all the goodness from it rather than health hazards.