Most fresh foods can only be kept safely for a short time, as they begin to spoil quickly. Since early times in history, people have devised ways to solve this problem and extend the shelf life of food.
In this article, I’d like to talk about the advantages of food preservation and briefly present the main methods.
Food preservation is beneficial because it allows us to protect the nutritional value of food and prevent spoilage. It inhibits the development, survival, or reproduction of microorganisms in food. As the activity of microorganisms decreases, the amount of enzymes and toxins they create also decreases. As a result, food can be kept unchanged for longer, regardless of the season. During preservation, we use physical, chemical, biological, or combined methods to change the living conditions of various microorganisms and thereby prevent or completely eliminate their growth and reproduction.
Deterioration of food means a decrease in its nutritional value, as well as a change in its taste, color, smell, texture, and chemical composition.
What are the methods of food preservation?
The preservation process refers to the various procedures that aim to preserve the original quality of food for as long as possible and to prevent its deterioration. You may also wish to learn why some food items spoil so fast.
To preserve food, we can choose from various physical, chemical, biological, or combined methods.
1. Physical food preservation methods
Physical food preservation methods include, for example, low and high temperatures, high pressure, filtering, and drying. The essence of physical preservation is to prevent the activity of microorganisms by physical action, without the use of foreign substances
Refrigeration or freezing food
Refrigeration can only be used for a shorter period and is not effective against some microorganisms, for example, salmonella or staphylococcus. We usually refrigerate fresh milk, dairy products, vegetables, and meat products.
Temperatures between 0°C and +6°C slow down changes in food caused by enzymes and pathogenic microorganisms. Refrigeration and freezing are advantageous because they change the original properties just slightly.
By freezing, at temperatures between -15°C and -50°C, we can stop the reproduction and growth of microorganisms in food.
Home kitchen freezers operate at -18°C. However, the surviving microorganisms become active again after thawing and continue their disruptive activity.
Not all foods tolerate freezing well, such as cucumbers, apples, or grapes. Meat, pasta, or desserts can be frozen for 6-12 months. The shock freezing technology is advantageous because the food freezes to -40°C in a few minutes. Since small ice crystals are formed in it, its structure is not damaged much.
Food preservation at high temperatures
Pasteurization is disinfection by high temperature, which takes place at temperatures below 100°C. Pasteurization destroys the vegetative forms of microorganisms, but not the spores. Over time, these remaining spores become able to take a vegetative form, multiply and thereby cause food spoilage.
During sterilization, the hermetically sealed cans are heated to a temperature between 100-125°C. The duration of the sterilization treatment varies depending on the food, from 10 to 50 minutes. We use it to preserve canned meat, fish, vegetables, and milk. Sterilized foods can be safely consumed for months, even more than a year.
During sterilization, mold and its spores are destroyed, but it is not effective against all types of bacteria. The nutritional value of sterilized food is lower than that of fresh food. As a result of high heat, some vitamins break down, and the structure of proteins and fats changes.
Food preservation by dehydration
Drying removes moisture from solid foods such as meat, fish, vegetables, or fruit. It prevents the growth and reproduction of microorganisms by removing the water necessary for their existence.
Dehydration is a traditional, ancient method of preservation when food is dried in the open air or a sunny place. The modern, industrial process is carried out with flowing hot air, between 40 and 70°C.
2. Food preservation using chemical methods
During chemical preservation methods, various natural or artificial chemicals are added to food. These preservation methods include the use of natural acids that change the pH value of the food, as well as the use of phytocides (natural antibiotics).
Natural chemical preservatives include smoke, salt, alcohol, vinegar, and sugar, which, when used in the right concentration, extract moisture from food.
The consumption of chemical preservatives belonging to the group of nitrates in large quantities is not recommended due to their harmful effects on health.
3. Biological food preservation
The advantage of the biological food preservation method is that it is natural and safe. Essentially, with biological preservation, we create suitable conditions for the growth of beneficial microorganisms.
By adding salt to some vegetables, lactic acid fermentation starts, which prevents the growth of microorganisms that cause rotting. Lactic acid gives a fresh, sour taste to pickled vegetables, such as peppers, cucumbers, cabbage, cauliflower, beets, olives, and red onions. Lactic acid preserves the vitamin C content of vegetables and contributes to the synthesis of B-complex vitamins.
4. Combined food preservation procedures
One of the old, traditional meat preservation methods is a combination of salting, smoking, and drying. Salt absorbs moisture, which hinders the activity of microorganisms. The compounds in the smoke have an antiseptic effect, and the heat dries the meat.
Lyophilization is a relatively new method of preservation, which is carried out by the combined use of freezing and drying. Its advantage is that it preserves the food’s color and taste as well as its vitamin content to a large extent.
In their fresh state, most foods can only be stored and consumed safely for a short time. Therefore, the important and beneficial effect of preserving food is that it maintains the quality of food for a longer period.
Physical, chemical, biological, or combined methods can be used to preserve food. With these, we extend their consumption time and nutritional content.
In addition to traditional food preservation methods that are still effective today, modern technologies are widely available for everyone. You may also wish to read my article about the oldest honey in the world.
My name is Debora, the founder of My Delicious Sweets, and a qualified confectioner with broad experience in the confectionery industry. On my blog, I will share important, interesting, and fun facts about food, along with some of my favorite recipes.