Controlling food preservation is often a challenge. Poor management can lead to health risks, especially in professional establishments such as restaurants and canteens that manage large food stocks. The main objective is to maintain food safety by avoiding bacterial proliferation, while maintaining the taste and nutritional qualities of products. Understanding preservation methods allows better management of food stocks. Technological change has brought more advanced conservation techniques, which can be combined with traditional but effective methods. What are the best preservation methods? In the heat? In the cold? Or using another technique? Discover them in this article.
Refrigeration is a widespread preservation method, whether by individuals or professionals. This is because the cold interrupts or slows down cellular processes, enzymatic reactions, and the growth of microorganisms, thus extending the shelf life of foods by reducing their spoilage. However, microorganisms that may be present are not eliminated and can resume their activity once the temperature conditions become suitable again.Learn about three low-temperature preservation techniques.
This method involves cooling foods to extend their shelf life. In a refrigerated state, animal and plant tissue cells remain alive for a variable length of time, and cellular metabolic activities slow down. The storage temperature for the most perishable and sensitive foods varies between 0° C and +4° C.
Freezing reduces the temperature of foods, turning the water they contain into ice. It takes place at -18°C, stopping all enzymatic and microbial activity.This process of crystallization of water in food decreases the quantity of water available for biological reactions, thus slowing down or stopping the activity of microorganisms and enzymes. The shelf life varies from 1 to 24 months depending on the product.
Freezing involves freezing healthy and fresh foods quickly, by lowering their temperature very quickly until reaching at least -18° C everywhere in the food. This process allows the water in the cells to crystallize finely, reducing cell damage. Frozen foods maintain their texture, taste better and can be stored longer.Frozen products should be clearly labeled and should not experience temperature fluctuations during storage or transport.It is important not to refreeze frozen or frozen products once they have been thawed.
Deep freezing is rapid freezing at a very low temperature, used by professionals for prepared meals, while freezing is its domestic equivalent.
Learn more about the difference between freezing and deep-freezing in this article. Frozen or frozen product: what is the difference?
Preserving food by heat is effective for long-term preservation.
This thermal process exposes food to temperatures in excess of 100°C, eliminating any microbial presence. This method ensures that food products are preserved at room temperature.
This method combines two distinct approaches:
Products treated with this technique can be stored for several years at room temperature, up to a maximum of five years. They are marked with a date of minimum durability. After this date, although the foods do not pose any health risks, they may lose taste or nutritional quality.
Pasteurization is a technique that aims to eliminate harmful microorganisms and prevent deterioration. This method destroys pathogenic microorganisms by exposing food to temperatures ranging from 85° C to 100° C for a specific time, followed by rapid cooling. The main advantage of this technique is the preservation of the qualities of food products, including their taste. Pasteurized products have an expiration date and must be stored in the refrigerator. This technique is widely used for dairy products, fruit juices and vegetables.
Changing the atmosphere around food is an effective preservation method.
Vacuum packaging decreases the amount of air surrounding the food, thus reducing the impact of oxygen. This process limits the development of microorganisms, which are a major cause of product deterioration, and also prevents oxidation reactions, which can also degrade food.
Modified atmosphere packaging uses airtight packaging to replace the air around the food with a gas or a mixture of gases specific to the type of product, thus extending its shelf life. It is common to combine this method with storage at low temperatures throughout the life of the product. Products packaged in this way generally have a label with the words “packaged in a protective atmosphere”.
Preservation by acidification is based on the fermentation process, which is the natural transformation of one or more food ingredients through the action of yeasts or bacteria. Three types of food transformations by fermentation are particularly significant:
Smoking, or smoking, is an old method that consists in exposing food to smoke from the combustion of plants. This process is used for aromatization and/or coloring. It is mainly used for meat and fish. In fact, drying followed by smoking makes it possible to preserve them thanks to the effect of dehydration and the antiseptics contained in the smoke.
Dehydration and drying involve the partial or total removal of water from food. Reducing water activity prevents the proliferation of microorganisms and slows down most chemical or enzymatic reactions responsible for deterioration.
Freeze-drying is a process that freezes food before placing it under vacuum, allowing water to pass directly from solid to gaseous state (sublimation). This technique preserves the shape, appearance and aromatic quality of products, which is often higher than that of dried products. Because of its cost, this technique is mainly used for high-value foods, such as mushrooms, instant coffee, some instant soups, and breakfast cereals.
Salting consists in exposing the food to salt, either by applying it directly to its surface (dry salting), or by immersing it in a saline solution (brining). Cheese factories and charcuteries use this technique extensively. But also to preserve certain fish (such as herring and salmon) or vegetables (condiments).
Pickling is done by immersing foods such as charcuterie, cheeses, cheeses, fish and condiments in a solution of salt, water, herbs, sugars and sometimes authorized additives.
Confectionery involves the slow cooking of foods in fat (pork, goose, duck) after coating them in sugar, and dipping them in sugar syrup (confectionery, candied fruits). This technique can also be done by keeping them in alcohol (fruits in brandy), vinegar (capers, pickles, pickles, onions) or in a sweet and sour preparation (chutney).
