People have always had to find ways to keep food safe to eat. Methods to dry, smoke and salt food were invented thousands of years ago. This storage method keeps food safe to eat for long periods of time. Today, canning is one of the most popular methods of storing food.
Clean fruits or vegetables are placed in glass bottles. The food can be put into the bottles either hot or cold. The cold method is used for soft fruits and vegetables that could lose their shape or taste. They take up less space in the bottles.
After the food has been placed in glass bottles, boiling water is poured into the bottles to about three centimeters below the top. The bottles are placed in a large container filled with warm water that is then brought to a boil.
The water must completely cover the bottles, from three to five centimeters over the top. When the water boils, any air in the bottles will be expelled. The boiling continues for several minutes. Then the bottles are allowed to cool. Finally, they are placed briefly into cold water. In other words, a vacuum （真空）is created.
When the bottles are completely cool, notes can be placed on them to identify what is inside. The bottles can then be stored in a cool, dark place at a temperature of between 4℃ and 21℃.
It is also a good way to store food for six months to a year, or even several years, in case of an emergency. It does not cost much to continue canning every year once the equipment has been purchased.
A. The process of canning is much more recent.
B 
This makes a strong barrier to keep the air out.
C. One popular method of canning uses a water bath.
D. Firmer fruits and most vegetables are usually cooked.
E. Canning uses heat to kill bacteria that cause poisons to form in food.
F. Then covers are placed on the bottles, but they are not turned all the way.
G. Canning allows your family to enjoy foods that might not come fresh throughout the year.
