temperature becomes too high for the germs to exist (212° F. or higher).

210. What are the Methods of Canning? - Several processes are used in canning. The oldest is the " open kettle" method. The food is put into a kettle and boiled. Then it is dipped out, put into a thoroughly cleaned and sterilized can, and sealed. How is the can sterilized, or freed from

germs?

In changing the food from kettle to can, there is, of course, some little danger that bacteria or other germs will get on the fruit. There is also danger that germs may lurk in reused can covers, if they, too, are not very well sterilized by thorough boiling. The cans should always be filled to overflowing and no air bubbles canner, mometer. should be left in them. Why?

Escape for expanding air

and steam

FIG. 122. The steam with a ther

The newer method of canning is the "coldpack " method. The government has an agricultural bulletin devoted to the description of this process; it gives information as to how long each particular food should be cooked and how each should be handled (Fig. 122).

If fruit is to be canned, it is made ready, placed in clean cans, covered with a sirup, and then the whole can is heated to the temperature of boiling water or higher. Sometimes the can is heated in the oven, sometimes by steam; but in the home the method of immersing the can is most often used (Fig. 123).

Vegetables are first

blanched," ," that is, are put into boiling water for a short time. Then they are chilled by cold water and are packed. Salt and sometimes water are added and then the cans are heated The lids are put on the cans before they are heated, but they are not sealed tightly until the can is taken out of its water or steam bath. Vegetables have to be heated, or "processed," as we call it, much longer than the fruits. The reason for this is that there are spores on the vegetables, which are not killed by heat unless the heating is carried on for a great length of time.

"Intermittent heating," that is, heating several times, is often used to preserve vegetables; it is carried out by heating the can of vegetables for

20008

FIG. 123. The hot water

a little while on each of three days. The first heating is not long enough to kill all the spores, but when the vegetable begins to cool and reaches a nice, warm canner, made out of a wash temperature, the spores that reboiler having a double bottom. main develop into the growing stage. The next day the can is heated, and as the bacteria in the growing stage are easily destroyed, the developed spores are killed.

The cold-pack method makes more attractive canned products possible, because the fruit and vegetables are put in whole and are not handled again; hence they keep their shape. Tomatoes canned in this way make salads possible in the winter. The flavor and color are much finer. When you enter a house in which canning is being done by the open kettle method, the odor of the fruit is noticeable even though the cooking is being done in another room. Why? Much of the flavor of the

fruit is lost in this odor. Much of the color is lost, too, by the open heating. When fruit is cooked in the can, its flavor and color are retained.

211. Does Canning Pay? - Do you think that people ought to cultivate the habit of canning? If we could once see the amount of good food that goes to waste in the ordinary family garden, we would realize, with a shock, that there is no better way to practice saving, or thrift, than to can for winter's use the vegetables and fruits of summer. Think of it! It has been estimated that half of all the fruit and vegetables nature grows for us are wasted every year. Sometimes they remain neglected in the garden; sometimes they are sent to market and through bad methods of packing or selling are allowed to spoil, unsold.

What examples of avoidable waste of food do you know of in your community? How could such waste be remedied?

212. Canning as a Factory Industry. a Factory Industry. Have you ever thought how canning has changed our method of living? People find it so convenient to have the vegetables of summer all winter long, and so enjoy having on their tables the perishable products of distant regions, that the canning of fruits, vegetables, fish, and meat has become one of the large industries of the United States. In some cases the food is partly cooked before it is canned. This is true of sweet corn. Most foods, however, are packed cold. After the cans are filled, they are capped by machinery and then heated ally under steam pressure.

usu

The machinery which has been invented for the filling of cans, for moving them, and for heating and preparing the food to put into the cans, makes the canning process very easy and very rapid. Peas, for example, are canned in great quantities. The way in which they are graded for size is very interesting. The peas are passed over sieves or into a revolving cylinder having four sections, each with differentsized holes. The holes in the first cylinder are very small, those of the second are a little larger, and so on. The smallest peas are thus separated out first. They are the most expensive.

213. Do Preservatives Harm Foods? Why go to all this trouble to preserve food by heating it and keeping it in air-tight cans? Why not put into the food a small amount of some chemical, such as borax or formaldehyde, which will destroy the germs and prevent natural decay? The answer of science is that such chemicals or preservatives are either poisons, or they keep our food from digesting properly. Food so preserved does us little good, but is largely wasted. In addition to this, food of poor quality, or slightly rotted, may be treated with preservatives and then sold to us as good food.

Children are in great danger when preservatives are used in milk, because milk forms so large a part of a child's diet.

Do you think a wise housekeeper will consent to feed her family with food containing injurious chemicals, or to put "acids" in her canned goods just to save herself the trouble of canning or preserving food properly?

214. Exercises. 1. Give the reason why some foods must be canned if you wish to preserve them.

2. Give three good reasons for using the cold-pack method of canning.

3. Why must you not seal the can lid tightly, in the cold-pack method, before you begin heating?

4. If a tin can of tomatoes bulges inward, are the tomatoes likely to be spoiled? If it bulges outwards? Tell why.

5. Why is a “tin" can, that is, a can of iron covered with tin, used instead of one of iron alone? Would one covered with copper do as well?

6. What do you think of the use of chemicals to preserve the color of food, that is, to keep peas green and to redden canned cherries? What do you think of the use of artificial dyes in candies?

7. How does the atmosphere's pressure help to keep a glass fruit jar tightly sealed?