June 2, 2006 -- New research shows that fresh-cut fruit may not lose much of its nutrients when stored in the refrigerator for a few days.
Scientists sharpened their knives and put mangoes, pineapples, kiwi, strawberries, watermelon, and cantaloupe on their shopping list.
They wanted to see if fresh-cut fruit lost antioxidants -- including vitamin C, carotenoids, and phenols -- when stowed in a refrigerator at 41 degrees Fahrenheit in a clear, plastic container that wasn’t airtight.
The key finding: “In general, fresh-cut fruits visually spoil before any significant nutrient loss occurs,” write the researchers. They included Maria Gil of Spain’s Research Group on Quality, Safety, and Bioactivity of Plant Foods.
The study appears in the May 12 early online edition of the Journal of Agricultural and Food Chemistry.
Fruit in Focus
The tests were done at the University of California, Davis.
The scientists bought double quantities of each type of fruit. They refrigerated half of the fruit, leaving it whole.
The researchers chopped the rest of the fruit, peeling it if necessary (such as with kiwi). They refrigerated the fresh-cut fruit in clear plastic “clamshell” containers that weren’t airtight.
Every day for the nine days, the researchers rated the fruits’ visual appeal on a nine-point scale. The highest rating was for fruit that looked “excellent.” The lowest score was for fruit that looked “poor, unusable.”
The scientists checked the nutrients in the fresh-cut fruit every day. For comparison, they also ground up whole fruit every day for nutritional tests. All fruit were stored at the same temperature.
Looks Faded Before Nutrients
The study shows that the fresh-cut fruit didn’t look as great days after being sliced as it did when had just left the cutting board.
No surprise there -- the researchers didn’t add any chemicals to prevent the fruit from turning brown or losing its visual appeal. They had already trashed any fruit that was overripe or mushy when purchased.
Nutrients lasted longer than beauty. For instance, here’s how much vitamin C each type of fresh-cut fruit lost in six days:
- Mango, strawberry, and watermelon: less than 5%
- Pineapple: 10%
- Kiwi: 12%
- Cantaloupe: 25%
Carotenoids in mango and watermelon cubes increased as a result of exposure to light, the study shows.
Surprise in the Fridge
The results surprised the researchers.
“Contrary to expectations, it was clear that minimal processing had almost no effect on the main antioxidant constituents,” write Gil and colleagues.
They call for studies to test how postcutting treatments -- such as methods used to delay softening and browning -- affect the longevity of nutrients in fresh-cut fruit.
Meanwhile, Gil’s team isn’t recommending that people push the limits of fruit storage, even in the refrigerator. The golden rule of food safety still applies: When in doubt, throw it out. With summer fruit coming into season, there’s plenty more where that came from.