Research shows that frozen fruits and vegetables in American supermarkets have higher nutritional value than fresh fruits and vegetables.

Fatima Hachem, senior nutrition officer at the UN Food and Agriculture Organization, said that food is most nutritious when harvested, and fresh crops start to lose nutrients from the moment they are harvested.
Vegetables and fruits need to use their nutrients to maintain cell life after picking them. Some nutrients are particularly easy to lose, such as vitamin C, which helps the body absorb iron and lowers cholesterol, quickly lost when exposed to air and light.
After the fresh fruits and vegetables are picked, they must be transported to the packaging factory for grading and packaging and then distributed to supermarkets. The transportation process will take a lot of time. To make the fruits and vegetables that arrive at the supermarket look fresher, farmers even pick them in the ad. Theirtheir nutritional value is naturally not as good as naturally mature fruits and vegetables.
Many people think that frozen fruits and vegetables are unhealthy, but frozen fruits and vegetables are not unhealthy, and they often retain more nutrients.
Frozen fruits and vegetables are usually freshly-ripened produce picked and frozen by field processors, sometimes with minimal blanching of the skins to maximize their nutritional value. Compared with the transportation and processing of fresh fruits and vegetables, the nutrient loss caused by the freezing process is much smaller. Interestingly, some frozen fruits and vegetables are given vitamin C during the packaging process to prevent browning; You may get more vitamins from these frozen fruits and vegetables than from fresh ones.
According to some studies from the University of California–Davis: 1. Fresh and frozen fruits and vegetables have similar amounts of carbohydrates, protein, fiber, and minerals. 2. Fresh fruits and vegetables lose half of their vitamins and phytonutrients during storage (within a week). 3. Less fat-soluble vitamins A and E are lost during freezer packaging than water-soluble vitamins such as vitamin C. The vitamin A/E content of frozen fruits and vegetables is higher than that of fresh fruits. 4. Frozen fruits and vegetables may contain more vitamins and phytonutrients than fresh fruits and vegetables that have been stored for several days. Consistent with many similar studies showing that frozen fruit is not necessarily nutritionally deficient despite long storage and is even more nutritious than some fresh fruits and vegetables in the supermarket.
 

Research shows that frozen fruits and vegetables in American supermarkets have higher nutritional value than fresh fruits and vegetables. PDF