Ответь на вопросы Answer the following questions:

Canning is a method of preserving food in which the food is processed and sealed in an airtight container. The process was first developed as a French military discovery. In 1809, a French confectioner and brewer, Nicolas Appert, observed that food cooked inside a jar did not spoil unless the seals leaked, and developed a method of sealing food in glass jars.
Glass jars were largely replaced in commercial canneries with cylindrical tin or wrought-iron canisters (later shortened to "cans"). Cans are cheaper and quicker to make, and much less fragile than glass jars. Glass jars have remained popular for some high-value products and in home canning.
Today, tin-coated steel is the material most commonly used. Modern double seams provide an airtight seal to the tin can. This airtight nature is crucial to keeping bacteria out of the can and keeping its contents sealed inside. Thus, double seamed cans are also known as Sanitary Cans. Developed in 1900 in Europe, this sort of can was made of the traditional cylindrical body made with tin plate. The two ends (lids) were attached using what is now called a double seam. A can thus sealed is impervious to the contamination by creating two tight continuous folds between the can’s cylindrical body and the lids.
Canning is a way of food processing to extend the shelf life of some food products. The idea is to make food available and edible considerably long after the processing time. Although canned foods are most likely assumed as low nutrition food due to some heating process and/or addition of preservatives, some of canned foods are in fact better in nutritive value in comparison to its natural form.
The packaging prevents microorganisms from entering and prolife rating inside. From a public safety point of view, foods with low acidity (a pH more than 4.6) need sterilization under high temperature (116-130 °C). Foods that must be pressure canned include most vegetables, meats, seafood, poultry, and dairy products. The only foods that may be safely canned in an ordinary boiling water bath are highly acidic ones (with a pH below 4.6), such as fruits, pickled vegetables, or other foods to which acidic additives have been added.
1. Give the definition of the process of canning.
2. When was canning discovered?
3. What kind of packaging was used first?
4. Why the glass jars were replaced by canneries?
5. Why is canning so popular?
6. What are the drawbacks of canning?
7. What peculiarities does canning have?