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The main methods of food preservation include the following:
Treatment:
Treatment includes the addition of certain ingredients such as salt, sugar, sodium nitrate and sodium nitrite to food. This is one of the oldest methods of food preservation. The processing is currently used to conserve processed beef and some other meat. The same method is sometimes used to save fish, potatoes, cucumbers and some kinds of nuts and walnuts.
Each of the components of the treatment has its own role in influencing foods. Salt slows the growth of microorganisms and removes some water from the food. While the sugar is purified and the equation of the hardness caused by salt. Nitrate and sodium nitrite salts help to preserve the red color in the flesh. Spices are added mainly to taste.
Canning:
Canning is the most common method of food preservation in industrialized countries. In this way, the food is placed in sealed receptacle containers, one of which is called a tray, whether a can of tin or glass. The caddy is then heated to kill and destroy microorganisms that can cause food spoilage. Food canning plants produce many canned foods such as fruits and vegetables. The food is cleaned and washed well before placing it in cans. After finishing raw food processing, the process of packaging itself includes five basic processes:
1 - packing. 2. Primary heating. 3. Lock cans
. 4. Heat treatment. 5. Cooling.
Storage at low temperatures or cooling:
Keep food fresh at 4 ° C. Storage at or near this level stops the growth and activity of most microorganisms that cause food corruption. It also reduces the activity of enzymes that cause undesirable changes in color, taste and texture of nutrients. Foods that need to be refrigerated include fish, meat, eggs, yogurt, fruits and vegetables.
Freeze:
The freeze removes heat from foods using low temperatures, slows the growth of microorganisms, and completely stops degradation or breakdown of nutrients. It is known that most foods, because they contain a high proportion of water, they freeze at temperatures ranging from 0 to -18 ° C vegetables are among the most important foods that are frozen. Vegetables must be boiled before freezing. The salik process prevents enzymes that are not killed during freezing from changing the taste of vegetables. Other foods that are frozen, other than vegetables, are meat, fish, poultry and juices. The food needs to be cleaned, peeled or prepared in one of the preparation images before freezing. The most common industrial methods of freezing currently include:
1 - Freezing on the boards or shelves
2 - freezing cold air currents
3 - freezing with liquid gases.
Drying:
Heat-drying is used to expel moisture from food to less than 15% of moisture, because microorganisms that cause food corruption need moisture to grow. When food is dried to the degree or extent that food is lost most of the water in it, microorganisms can not grow on it. There are several ways to produce dried foods, including:
1 - drying the sun 2 - drying on the flint - 3 drying in the tunnels
Freeze drying:
Is a process of freezing by freezing where snow under special circumstances can be transformed directly from the solid state to the gaseous state without first fusing into a liquid. This phenomenon is called sublimation. In ranching plants, water is removed from food while the material is in a frozen state.
Foods stored in a freeze-dried manner preserve the original taste and texture better than dried foods. In addition, they retain nutrients better. The freeze-drying process is also economically costly and therefore is used only with limited food. Frozen foods include instant coffee, dried soup mix and strawberries.
Food Additives:
Some substances are added to prevent corruption or to increase the nutritional value of food. Additives are chemical compounds used for food preservation when there is no other appropriate or effective means. , And government approval is required for the use of additives. Some additives help to increase the shelf life of food for use and consumer convenience. Food additives include: antioxidants, preservatives and other additives, such as ion-retention substances and laxatives, which prevent food hardening and help sustain food in an attractive consumer state. Preservatives prevent microorganisms from growing in foods that can not be conserved in other conservation methods such as freezing. Common preservatives include benzoic acid, sorbic acid and sulfur dioxide.
Radiation:
Food is processed by ionizing radiation, ie radiation that produces electrically charged particles. X-rays, gamma rays, and electron beams are images of radiation used to conserve food. The small dose of radiation kills bacteria. The cessation of enzymatic activity also causes no chemical changes in food, or only a few of these changes occur. The rays also kill insects in food, and prevent the germination of some vegetables.
Smoking:
Some types of meat and fish are processed by smoking. Smoke from wood burning contains some chemicals that slow the growth of microorganisms. The food to be smoked in the smoking building is suspended. The necessary smoke is provided by the slow burning of certain types of special timber.
In addition, some other conservation methods, such as pasteurization, fermentation, evaporation and storage in environmental conditionsC ontrolled to help save some food.
canning, parboiling, de-oxidizing, pasteurizing
