Contrary to the ideas received, frozen vegetables and fish are sometimes richer from a nutritional point of view than the fresh products that have a little dragged.
Metro, work, “freezer”: Many families do not imagine their lives without the frozen. Daily life does not always leave time to peel fresh vegetables or prepare a fish in the oven. A study published in 2009, however, questioned the nutritional virtues of this mode of preservation, if practical. Indeed, according to an article published by Spanish researchers in 2009 in the magazine Food Research International, a single day of freezing is enough to cause broccoli to lose 15% of their antioxidant properties. A leak that amounts to 23% for green beans and 26% for peas.
Folate, vitamin C and polyphenol kept intact
“Studies on all antioxidant molecules are not necessarily relevant, as some of them do not have an interesting effect on health,” commented Catherine Renard, director of the Safety and quality Unit of Products of plant origin at the National Institute of Agronomic Research (INRA). “On the other hand, with regard to folate, vitamin C and polyphenols that we need in our diet, the studies we have conducted show that their contents remain stable in frozen vegetables, once the bleaching stage has passed.”
Bleaching is a heat treatment of bringing the vegetables to 90-95 °c for a few minutes to deactivate the degradation enzymes. In fact, “only the carotenoids [of which the carotene belong, which is also called provitamin A, and lycopene, which has proven effects against prostate cancer, Editor’s note] Sometimes less well support storage when frozen: there is then a loss of 30% over one year for some products, “details Catherine Renard.
The nutritional quality of certain preserved vegetables
On the other hand, for some vegetables such as spinach, stresses the researcher, deep-freezing after picking guarantees better levels of vitamins and nutrients than the storage in the open air. Caution, do not thaw vegetables before cooking, because thawing destroys some of the vitamins. “A frozen vegetable can contain more vitamins than a fresh vegetable that has dragged several days on a stall and then in the kitchen,” adds Dr. Jacques Fricker, a nutritionist at the Bichat Hospital in Paris.
In the case of fish, their proteins, minerals and carbohydrates are resistant to freezing. But some lipids, including the famous omega-3s, are destroyed more quickly in frozen products. A fish caught six months ago almost no longer contains omega-3s. Unless it is whole, or if it has retained its skin, explains Jacques Fricker. The solution is to buy a whole fresh fish from the fishmonger and freeze it yourself. or turn to canned goods. “Canned sardines and mackerels are often a bad image because they are cheap products, but they are rich in vitamin D and omega-3s.”
No more than canned foods, frozen products are not to be banned from our food. The best approach is to prefer unprocessed products to cooked dishes, which are too rich in added sugar and salt, whether frozen or vacuum.