Interestingly, this five or six day period is also about the same time it takes for the cut fruits to spoil and become unusable anyway. So when your cut fruits look spoiled, not only has it lost some nutritional benefit, it's time to toss it out too.
Cut vegetables retain their vitamin C content longer. According to the United States Food and Drug Administration, cut or peeled vegetables will lose about half of their vitamin C content in one to two weeks.
The best way to store fruits and vegetables like apples, oranges, grapefruit, potatoes and other produce is unwashed with the skin, rinds, or peelings intact.
You don't have to wait until the last moment to cut your produce, but be sure you keep them stored in air-tight containers in your refrigerator. Having fresh fruits and vegetables ready to eat in your refrigerator may make it easier for you to make healthy choices at snack time.
How long should you keep them in the refrigerator? Use freshly-cut fruits within two or three days and vegetables within four or five days, to be sure you are getting the most flavor, best texture and maximum nutritional value.
María I. Gil, Encarna Aguayo, Adel A. Kader. "Quality Changes and Nutrient Retention in Fresh-Cut versus Whole Fruits during Storage." J. Agric. Food Chem., 54 (12), 4284 -4296, 2006. 10.1021/jf060303y S0021-8561(06)00303-7.
United States Food and Drug Administration. "Raw Produce: Selecting and Serving it Safely." Accessed February 10, 2012.http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm114299.htm.