At the moment, frozen raspberries, which have long storage times and do not need to be washed, have become the darling of the new era. So how much nutrition is there compared to frozen fruits and vegetables and fresh fruits and vegetables?
"Quick freezing" generally consists of three steps: pretreatment, freezing, and freezing storage. Changes in nutrients mainly occur in pre-treatment and frozen storage, and the freezing process has no effect on nutrients. The pretreatment process itself causes changes in food quality, mainly the loss of water-soluble vitamins and minerals. Almost all frozen vegetables require pre-treatment by boiling, steaming or microwave. In general, the degree of nutrient loss: boiled > steamed > microwave. However, due to the influence of different vegetables, different cutting shapes and sizes, even with the same pretreatment method, the nutritional loss is quite different. Let's take a look at the specific nutritional status of quick-frozen, fresh fruits and vegetables:
After picking fresh fruits and vegetables, VC is easily lost. For example, after a week of storage of fresh green beans in a 4°C refrigerator, the loss of VC is as high as 77%. The loss of VC in quick-frozen fruits and vegetables mainly occurs in the pretreatment process, and the VC loss caused by different pretreatment methods of different vegetables reaches 0-60%. However, since most of the frozen fruits and vegetables are additionally added with VC during processing, the detected VC content of some frozen fruits and vegetables will be higher than that of fresh fruits and vegetables.
Vitamin A & E, Carotene: These fat-soluble nutrients are not lost due to heat, but will increase. For example, the beta carotene content of frozen corn has increased nearly twice.
Minerals: Potassium levels are reduced, especially in quick-frozen spinach; calcium and magnesium levels are not affected.
The above is mainly the change brought by the pretreatment. In the later storage process, the nutrients are more or less reduced according to different packaging and storage temperatures. In general, the nutritional value of frozen fruits and vegetables is certainly not high, mainly reflected in natural VC, VB and antioxidants, but not as low as the legendary nutritional value.
