We all think that fresh spinach bought from the primeur or the market is the panacea? Well no.

Unless we supply an Amap *, which guarantees a direct link between producers and consumers, our dish will have a lower quality nutritional content than if we had prepared it from frozen!

Certainly, after eight months of cold weather, spinach loses some vitamins: their antioxidant capacity has indeed eroded by 21%. But the fresh leaves take even less of their game. Between the time they are picked, stored in crates, transported to the stalls, purchased and finally consumed, their benefits are reduced to a trickle. Stored for three days, spinach loses 50% of its initial vitamin C content .

Worse: this rate collapses to 17% over the next four days. In the end, frozen foods (usually processed by manufacturers immediately after picking) are therefore superior to them. In addition, "their taste is unchanged, so it's a good way to make your life easier," says Dr. Catherine Serfaty-Lacrosnière, nutritionist and author of "Secrets of Anti-inflammatory Food " (Albin Michel ).

Be careful not to generalize: all vegetables do not behave in this way.

Food freezing: effective cold weather plan?

A large Spanish study published in the journal Food Research International in October 2009 evaluated the nutritional qualities of twenty-five vegetables for everyday consumption according to their mode of conservation.

First revelation: some are indifferent to the sudden treatment. Cucumbers, artichoke hearts, eggplants, zucchini, lettuce and endive have the same antioxidant power whether they have been stored in a refrigerator, frozen at -20 ° C or kept in a box for eighteen months. This does not mean that they do not deteriorate over time, but that it is roughly equivalent regardless of how they are stored.

Fresh or frozen, their antioxidant intake is comparable. On the other hand, it is better to buy fresh vegetables from most other vegetables.

For proof: in the freezer, broccoli, chard, green beans and peas lose in a single day from 1% to 26% of their 5 health and anti-aging virtues. And after eight months of freezing, the damage is sometimes considerable: their antioxidant content drops by 30% to 40% on average, and up to 48% even for broccoli!

In the refrigerator, the nutritional losses are much smaller (0.3% to 8% per 24 hours). Unlike spinach, freezing is just a last resort for them. What shatter more than one prejudice.

The cabbage family pays an even greater tribute to the cold, since the bleaching preceding freezing deprives them of the majority of their anticancer properties. This operation considerably reduces the activity of myrosinase, the enzyme without which the antitumor compounds of broccoli and cauliflower can not exert their beneficial action. Since they are easily found at low cost in winter on the stalls, so they eat them fresh, raw or cooked less than seven minutes steamed.

Beware of expiry dates

Canned foods are not eternal.

"Stored in a cool and dry place, protected from light, they can be kept up to eighteen months for acidic foods (fruits, tomato ...) and five years for weakly acidic foods such as vegetables, "says Alix Lefief-Delcourt, author of" Keeping food is clever "(ed Leduc.s).

To avoid oddities, we rely on the date of optimal use (DLUO) written on the lid. But, once the box is open, you do not keep the products for more than forty-eight hours in the refrigerator (except the tomato sauce, three to four days of expiry).

Frozen foods do not keep either ad vitam aeternam . Those of the trade include a DLUO or a deadline of consumption (DLC). Counting twenty-four months for fruits and vegetables placed in a 4-star freezer (18 ° C), but much less (nine to eighteen months) for meat, fish and cooked dishes, because the cold does not prevent the fat rancidity.

Be careful with canned

Little surprise on the side of preserves: the antioxidant power of many vegetables has become very limited.

Only green beans really do well: they lose only "only" 13% of their antioxidants, which is less than freezing.

Asparagus, Swiss chard, beans, peas and garlic are also deteriorating. Their antioxidant capacity is reduced by a quarter to more than half when they have been canned and stored for several months. Celery beats all records: its antioxidant capital can be reduced to nothing.

It is not counted in the five servings of fruits and vegetables per day. Another major concern: manufacturers often add salt, and sometimes even sugar, as in cooked peas. Do not rinse the vegetables and drink the juice of canned foods to recover some of the vitamins and minerals is not ultimately such a good calculation. Especially if our tension is already high or if diabetes is watching .

Not to mention the risk of getting drenched with bisphenol A, an endocrine disruptor that may escape from the internal lining of cans and whose role in the occurrence of certain breast cancers was clearly demonstrated in May 2012 on waists ** . For a year, he has no longer the right of quotation in products intended for infants (small pots, teats, teething rings ...).

But food packaging (cans, soda cans ...) may contain more until the beginning of 2015. So, by then, distrust! We limit the canned food to the minimum portion.

The golden rules of home made

Making your own preserves requires impeccable hygiene to prevent botulism, a serious disease caused by bacteria.

• Wash hands thoroughly beforehand and thoroughly clean work surfaces, utensils and jars.
• Respect the sterilization time: at least an hour and a half for green vegetables, thirty-five to forty-five minutes for fruits in syrup and three hours for natural tuna.
• Use only fresh seasonal produce. Never frozen products.
• Fill the jars up to two centimeters from the edge, complete with a liquid (juice, syrup ...) and wait for the air pockets to rise to the surface before closing.
• After sterilization, check that the pots are well sealed.

To freeze foods themselves, they are chosen very fresh. The vegetables must first be blanched (briefly immersed in boiling water) then passed under cold water and dried.

* Associations for the maintenance of a peasant agriculture.
** Study of Tufts University, Boston, published in Proceedings of the National Academy of Science.