The can, whose primary quality is to ensure the preservation of food without adding ingredients, has become over time an essential in our kitchens.
It allows us to find products that are not in season, but also to preserve them for several years. Here is a review of what you need to know about canned foods.
How is food canned?
First, the food is blanched, placed in the jars intended for distribution, and subjected to a heat treatment called canning.
They are then heated to a temperature above 100°C for a variable period depending on their type. They are thus rid of microorganisms, toxins, and enzymes. This preservation process has evolved considerably in recent years, allowing better preservation of the texture and nutrient content of foods.
The containers, most of which are recyclable, can be made of glass, metal, plastic, or even complex cardboard. Canning is one of the safest ways to preserve food, and the advantage is that it allows it to be preserved for several years.
Cans can be stored
First of all, it is necessary to make the difference between the expiry date indicated by “to consume until” and the expiry date of optimal use “to consume preferably before”.
Most canned products have the best use label, which means they have a longer shelf life.
This expiry date allows the food to be consumed without danger even if the date indicated has passed. However, it is possible that it has lost some of its qualities (taste, texture).
According to the Canned Food Alliance (an American association bringing together companies active in the food industry of tin can manufacturers and steel producers), a can is edible two years after its date of purchase 2 subject to correct storage conditions (temperature below 23° C), while in France it generally does not exceed eighteen months.
These products have the longest shelf life, but once the can or jar has been opened it is recommended to place them in the refrigerator and consume them within forty-eight hours.
Canned foods are generally lower in nutrients, but that’s not always true.
In most cases, the canning process causes many nutrients to be lost. Less than five hours elapse between the time the food is harvested and the time it is packaged. Losses vary by food and nutrient.
For example, a canned tomato has a higher lycopene level than a fresh tomato, because the losses observed during storage are greater than those observed during canning. With regard to vitamins, they are destroyed up to 30 to 50% due to heat treatment.
For antioxidants, their preservation varies from one food to another, but it would seem that blanching is responsible for part of their destruction 2 (beets lose approximately 64%, peas 46%, spinach 32 %, chard, and broad beans 29%, asparagus 25%, green beans 13%). But the fats and fibers remain stable, so the content of these nutrients is comparable to that of fresh produce.
Fatty acids and carbohydrates are preserved, and would even improve the digestibility of foodstuffs.
The minerals are preserved at 50% unless bleaching is done with steam. The main concern is what is sometimes added during the canning process, as the juice from canning is often high in salt, which increases the sodium content of the food.
Canned foods lose some of their taste
Most canned foods lose some of their taste because the heat treatment seems to denature certain molecules.
In addition, the foodstuffs are bathed in a liquid rich in sodium, or in vinegar for cabbage, beets, and onions, which causes them to lose their original taste and give them a new, saltier one. However, the juice of the fruits, composed mainly of sugar, does not alter their flavor.
In some cases, additives are added to the preserves. They would help to increase the nutritional value of foods while preserving their freshness and taste.
Home-made preserves retain the taste of the food better because the preservation method is more delicate and meticulous. In addition, in order to optimize the preservation of flavors, it is recommended to choose ripe products of good quality.
It is best to rinse your food before eating it.
In fact, the juice from preserves is essentially composed of water and salt, sometimes sugar. This mixture of water and salt, called brine, allows food to be kept longer.
It is mainly used for fish and meat. Part of the salt thus migrates into the food and the concentration of salt increases, which is why people suffering from cardiovascular diseases or hypertension are sometimes advised against limiting their consumption of canned foods.
On the other hand, the juice of canned fruits rich in sugar can be consumed because it contributes to the preservation of the taste of foodstuffs. However, juice also appears to contain some of the nutrients from canning, so care should be taken to read product labels.
They indicate whether the liquid can be consumed and whether the food must be rinsed. Legumes should be rinsed, as this improves their digestibility. In fact, rinsing makes it possible to eliminate carbohydrates and complex sugars responsible for poor digestion.
You can make your own preserves
It is quite possible to prepare your own preserves. Hygiene must be impeccable in order to avoid any contamination and the risk of the development of bacteria.
It is therefore important to sterilize the jars beforehand and to ensure that they are not damaged.
To sterilize a container, simply boil it in water and let it air dry (do not wipe it).
It is also recommended to choose ripe and very fresh foods in order to lengthen their conservation time. They must then be blanched, placed in the jar, and then filled with a solution of boiling salted water for up to three-quarters.
Then close the jar and place it in a pressure cooker filled with water at 100° C. It will be necessary to wait for the water to cool before taking out the jars, which must be placed in a dry and cool place away from light. It is advisable to consume them within a year of their preparation.
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