John Presto, age 8, of Mount Joy, Penna for his question:
What, keeps canned floods fresh?
Food is spoiled by tiny plant microbes, too small for our eyes to see, Some are bacteria, some are yeasts and some are molds, These little microbes teem in the air and on the surface of everything we touch. There are millions of them on the cleanest hands and countless numbers in even the purest water, They share our world with us and they have a very important ,job to do, They are the microbes which cause decay. They attack fallen leaves, dead animals and all sorts of waste materiai and break these materials down into simple chemicals. These chemicals are the food for growing plants.
When they can, these teeming microbes attack our food and feed and multiply at a great rate, This is what causes the food to spoil, to lose its flavor get a bad smell and turn rotten. Actually, the microbes are breaking the food down into simple chemicals, But it is now spoiled, rotten and decayed and no use to us. So we must protect our food from these hungry invaders, There are several ways to keep the microbes from spoiling our food and one of them is by canning.
Luckily for us, the little decay microbes are very fussy. They can feed and multiply only when things are just right, They refuse to work when there is too much salt or sugar. They cannot abide peppers and strong spices. They must have moisture and they must have oxygen. Most important, too much heat or cold puts them out of business.
We use all these tricks to protect our foods from spoiling, We preserve beef and pork with salt and ham with strong, sweet spices. We make jams and jellies with plenty of sweet sugar. We dry or dehydrate fruits and keep all kinds of foods in the chilly refrigerator. All these tricks do not damage the food for us, but they destroy manyof the microbes and stop the rest from getting to work.
Most of our food is preserved in cans, We call them tin cans, although they are made of steel with only the thinnest coating of tin to prevent rusting, Cans use two tricks to stop the microbes from spoiling the food. Glass bottles and other sealed containers use the same tricks. They use heat to destroy most of the microbes and they seal up the food without air and without air, these tiny yeasts, molds and bacteria cannot grow and multiply.
The food that goes to the cannery, like everything else in the world, teems with living microbes. Many of them are washed away. The food is then packed and heated to where all or most of the microbes are destroyed, The sealing of the cans or bottles shuts out the air supply, No decay microbe can keep busy without a good supply of oxygen, so the food in the can stays fresh.