Canning food
...teria and other micro-organisms that cause poisons to form in food. Canning also takes away the air that these organisms need to live. One popular method of canning uses a water bath. 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. Firmer fruits and most vegetables are usually cooked. 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. Then covers are placed on the bottles, but they are not turned all the way. 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. This makes a strong barrier to keep the air out. In other words, a vacuum is created. When the bottles are completely cool, notes can be placed on them to identify what is inside. The bott...