The word conservation comes from the Latin conserve - "preservation." Attempts to extend the shelf life of products have been made by people since ancient times, and the first successful experiments are considered to be made in Ancient Egypt. Found in our time, Egyptian "canned food" - resin-bonded clay containers with fried ducks in olive oil, even after almost 3 thousand years are good for food!
Nevertheless, despite the success of the Egyptians, then the Romans and other peoples in canning, food processed in this way did not become widespread - the technology was not worked out, the products often spoiled anyway, so people preferred to dry and salt food. Strictly speaking, salting and drying are also ways of preserving. However, we want to talk about the invention of exactly the method that is understood by canning now: about the heat treatment of products hermetically sealed in jars.
The inventor of canning was Nicolas François Apper. For Napoleon Bonaparte's army, it was necessary to invent a way to preserve food, and a large monetary reward was promised for the invention of this method in 1795. And so, in 1804, this method was finally invented. Nicolas Apper discovered that if food is placed in champagne bottles, sealed and boiled in boiling water, then food can be stored for a long time without spoiling. The first canned food made in this way: broth, fried meat, jam.
Since it was inconvenient to take food in glass containers with you, they began to look for other options, and soon the Englishman Peter Durand patented the iron can, although canned food in glass took its rightful place on store shelves and home cabinets. The first iron cans were inconvenient, quickly rusted and contained lead, but literally a few years after their invention, the United States began industrial production of cans that were no longer different from modern ones.
Since then, canning has not lost its relevance - it is still an unrivaled way to keep food healthy for a long time. True, the ways to simplify the canning process continue to be improved, to make it faster and safer, to preserve the maximum of useful substances in the product, to give it an excellent taste and aroma.
Canning and pasteurization: question - answer.
— What is the principle of canning?
Foods deteriorate under the influence of certain microorganisms and enzymes. Preservation partially inactivates or completely destroys these enzymes, inhibits the vital activity of microorganisms spoiling food or completely destroys them. This increases the shelf life of the product significantly.
— What is sterilization?
Product processing in a hermetically sealed glass or tin container. Sterilization is carried out at temperatures above 100 ° C (usually 113 -120 ° C) and under pressure, usually in a special avtoklav. The holding time depends on the type of product and the volume of the container. This method kills bacteria, destroys many enzymes, and allows you to destroy even heat-resistant bacterial spores. Proper sterilization is one of the safest ways to keep food edible for months or even years.
— What is pasteurization?
Continuous heating of the product at a relatively low temperature, usually 65-85 ° C. For pasteurization of some products, sometimes heating up to 60 ° C is enough, others need to be heated up to 93 ° C. During pasteurization, bacteria die, but their spores survive. That is why food is subjected to pasteurization, designed for not too long storage, and it is usually recommended to store it in the cold.
PThe shelf life of pasteurized products can be increased by tendalization - pasteurization 2-3 times every 24 hours. However, this reduces the nutritional value of the product. An interesting fact: the pasteurization process was named after its inventor, the outstanding French chemist and microbiologist Louis Pasteur.
Why are glass jars rolled up and tin cans hermetically sealed?
To keep food away from air. It can carry spoilage bacteria along with it, and - and this is the main reason - the air causes oxidation, which accelerates the spoilage of food.
— Are iron cans harmful to health?
No, provided that the container is of high quality: made of white lacquered tin-plated and chrome-plated sheet, without chips and deep dents. Low-quality cans can transfer metals and other harmful substances to food. After opening the canned food, its contents, if you are not going to eat it in one meal, it is better to transfer it to another dish, since any can begins to oxidize.
What foods are suitable for canning?
Almost any, just for each type of product choose the optimum temperature and method of preservation for its processing. Not only traditionally harvested meat, fish and vegetables with fruits are subject to conservation, but also seafood, seaweed (seaweed and others), cereals. In France and other countries, you can even find canned pastries!