That news appears in next week's edition of the Journal of Agricultural and Food Chemistry.
The researchers aren't suggesting that anyone eat spoiled food. That's a food safety no-no.
But their findings show most fruits and vegetables don't lose their antioxidants when they start to look bad.
"In general, fruits and vegetables visually spoil before any significant antioxidant capacity loss occurs," write the scientists, who included Claire Kevers, PhD, of the Plant Biology Institute at Belgium's University of Liege.
Fruit and Vegetable Study
Kevers and colleagues visited a wholesale distribution center in Belgium and bought 29 different kinds of fruits and vegetables.
Their shopping list included apples, apricots, asparagus, bananas, broccoli, carrots, celery, cherries, cucumbers, French beans, garlic, black grapes, green grapes, green peppers, kiwifruit, leeks, lemons, lettuce, melons, onions, oranges, pears, black plums, red peppers, spinach, strawberries, tomatoes, and yellow peppers.
As soon as Kevers and colleagues got back to their lab, they measured the antioxidant levels of those fruits and vegetables.
Black grapes, strawberries, and red peppers were particularly high in antioxidants.
The researchers then stored the fruits and veggies at room temperature or at 39 degrees Fahrenheit.
That temperature is in line with the U.S. Department of Agriculture's recommendation to keep refrigerator temperatures at 40 degrees Fahrenheit or lower.
Nasty but Nutritious?
The scientists stored the produce until they saw signs that the fruits and vegetables were spoiling. That took between seven days (for apricots) and 51 days (for carrots).
Kevers' team measured the antioxidant levels in the spoiled items.
For the most part, antioxidant levels rose or were stable in the fruits and vegetables during storage in the researchers' lab.
Broccoli, spinach, and bananas were among the few exceptions that had lower antioxidant levels when spoiled compared with immediately after being bought.
How did those foods taste? The researchers didn't go there. Their study was about measuring antioxidants, not tempting the taste buds.