In contact with air, heat or moisture, food riots, lose their freshness. In fact, the microscopic organisms called bacteria live all around us, on the fingers, in the air, in the intestines, and so on. and are the primary source of food deterioration. To live, most of these bacteria need water, raw materials (nutrients from food), energy in the form of heat and oxygen. So to take full advantage of his food and this over a longer or shorter period, man has sought ways to keep them. To achieve this, it is necessary to deprive microbes of one or more of their vital elements to slow their development. That’s when different methods of conservation have been developed. Each method results from the implementation of a process conferring advantages in terms of practicality and nutritional quality.
Drying As A Means of Preserving Food
The drying is a preservation technique used since the Neolithic it 4000 years ago. At the time, it consisted of exposing the foodstuff to the sun until it lost its water content, preventing the proliferation of bacteria. Oven drying has therefore followed to make room today for various other techniques such as the use of the infrared ramp, hot air dryers, heating cylinders … following drying, products obtained such as date, figs, apricots, cereals, etc. are packaged in packaging that protects them from moisture and external contamination.
Food Preservation By Heat
Several techniques are used to preserve by heat. Whatever they are, the goal is to destroy all pathogenic microorganisms that cause food spoilage. Here, the vital element to the development of the bacterium on which one acts is oxygen.
It consists of raising the temperature of the food between 70 and 100 ° C and suddenly switching to cooling. The food properties of the food are then preserved. This process is used in the industry to preserve fruit juice, milk, honey.
- Ultra-High Temperature Treatment Here, the temperature of the product is raised above 135 ° C. An instantaneous cooling is then carried out as in the previous case. Then, the food will be substantively conditioned at room temperature or positive cold due to the presence of a residual bacterial flora. A practical example of ultra-high temperature treatment is milk sold in supermarkets.
- Appertisation (sterilization)
This third method of conservation by heat discovered by Nicolas APPERT around 1810 is to bring the food temperature to more than 100 ° C. This temperature varies depending on the nature and acidity of the food. The heat to be applied is inversely proportional to the acidity of the product. In this way, we proceed to the destruction or total hibernation of the microbes contained in the commodity. These packaged products are then packaged in sealed metal boxes or in sealed glass jars where they can remain for up to 5 years.
Cold Preservation Techniques
The refrigeration and freezing are conservation techniques best known cold. Unlike conservation by heat, the micro-organisms will not be neutralized here, but the cold will serve to stem their spread.
Refrigeration is something we do every day. It involves storing food in a refrigerator at a temperature between 0 and 4 ° C. The shelf life is a few days or even weeks.
As for freezing, the target temperature is -18 ° C. The product is kept there to solidify the water it contains. Generally, with this method, the product can be kept longer than in the case of refrigeration (several months).
In addition to these two techniques, freezing is also a means of cold storage. It consists in very quickly lowering the temperature of a foodstuff below -18 ° C of a simple freezing. The freezers reduce the temperature to -40 ° C leading to the formation of ice crystals thus preserving the nutritional quality of the products. Its shelf life is longer than that of freezing, as it can last up to a year.
New Food Preservation Techniques
With the evolution of technology, sharp preservation methods have been put in place. Ionization and high pressures are part of it.
This is a physical procedure consisting in exposing the food to electromagnetic radiation(X-rays) or to electronic radiation (β radiation). This exhibition aims to destroy all microbial organisms while maintaining the nutritional quality of the product. After the implementation of the process, refrigeration or freezing is required for the preservation of the product.
- The Pasalisation
This process consists of applying very strong pressure on the product to eliminate microbes. Speakers designed for the operation allow putting the food under a pressure ranging from 4000 to 6000 times the atmospheric pressure. The results of this technique are remarkable, but the cost of its implementation is that its use remains limited today.
Salting is a conservation method used by the Romans in the first century BC. It is simply to sprinkle the foodstuff with salt. Thus, the concentration of salt to always balance between two bodies, the water in the commodity migrates to the salt while the salt enters the product. Thus, the food is deprived of a large amount of water that does not favor the development of bacteria. This technique is often used in cheese and charcuterie as well as for the preservation of certain fish such as herring, salmon or cod.
Vacuuming: The Best Method Of Food Preservation With Vacuum
The technique of vacuum consists of rarefying a gas or a gas mixture by the application of a pressure lower than the normal atmospheric pressure which is also called “depression”. The action of the vacuum thus consists in removing all the oxygen from the environment of the product. In doing so, the survival conditions of the bacteria are altered. The product can, therefore, be conditioned at ambient temperature. This technique requires precision and rigor, it is advised to specialists to follow a training in the field before implementing it. Thus, Choose the best foodsaver machine to preserve the food fresh.
Always in search of new methods of conservation more effective, other techniques develop. These include ohmic heating, pulsed magnetic fields, microfilming or ultrasound. These processes are little known because of the economic, industrial and regulatory constraints that accompany them.