Time-Table

Questions

1. What does "preserve" mean?

2. What causes food to spoil?

3. What is meant by bacteria? Germs?

4. What are favorable conditions for the growth of germs or bacteria?

5. Name opposite conditions.

6. Would these conditions hinder their growth?

7. Name five different ways of preserving food?

8. What is meant by "canning."

9. Explain what you did in your Lesson today.

10. What kind of jar did you use today?

11. Is a special canning steamer necessary?

12. What may be used for canning purposes?

13. What is the secret of successful results in canning?

14. How long should tomatoes be cooked?

15. How long should asparagus be cooked?

SUGGESTIONS FOR HOME APPLICATION. CANNING OF VEGETABLES AND FRUITS.

Canning is considered the best method of preserving food. When using this method, care must be taken that the micro-organisms on the article and the utensils with which it comes in contact during the process of preparation, are destroyed. The jar must then be sealed so securely that lib germs can possibly enter it.

We learned that some micro-organisms produce spores and that these spores are hardier than the parent cell.

While micro-organisms in food heated to the boiling point, for 10 or 15 minutes may be killed, the spores might require an hour or more. When food is canned by placing the cans in boiling water long enough to destroy all spores, the process is known as continued sterilization. We do know organisms are present in the article we wish to preserve. Experiments prove that germs found in fruit and fruit juices may be killed by boiling the fruit from 10 to 15 minutes.

Selection Of Jars For Canning

There are several kinds on the market. The ordinary screw top jar is the one most commonly used. It is inexpensive and with care is satisfactory. The tops, however, break easily and must be replaced often. There is a similar jar that has a fitted glass top held in place by a metal screw cover. If the sterilization is properly done when this jar is used the air is driven out of the jar by steam and upon cooling, a vacuum is formed on the inside which clamps down the glass top against the rubber ring. This seals the jar automatically and the metal ring can then be removed.

The Economy Jar requires no rubber ring, but is fitted with a metal top with the cover screwed on securely aside for 24 hours, the spores will having a groove around the edge. This groove is lined with a substance which, upon heating, melts and forms a seal that takes the place of the rubber ring.

These metal tops must be renewed each year because on opening the jar they must be punctured.

There is another jar considered satisfactory which is provided with a rubber ring and a glass top held in place by a simple wire spring.

As vegetables often spoil after being sterilized because of defective rubber rings, we should buy good ones. Usually black rubbers are more durable than the white ones. It is best to buy good grade jars. Those with wide mouths are the best.

A wash boiler is good for steaming. The bottom should be covered with a rack or false bottom. This may be of wire netting made of galvanized wire or of narrow strips of wood fastened onto 2 strips at each end. A heavy layer of straw or several thicknesses of paper or cloth will answer the purpose. It is absolutely necessary to cover the bottom of the boiler as the jars will break if they come in direct contact with the heat.

Fractional Or Intermittent Sterilization

Vegetables and fruits may be canned by a process known as fractional or intermittent sterilization. Experiments prove that the spores, which correspond to the seeds of the higher plants, with moisture and a moderate temperature germinate very rapidly. If food is put into sterilized cans and heated to the required temperature (165 degrees Fahrenheit for the material in the center of the can) for 15 minutes the micro-organisms are killed, but if there are any spores present, they will survive. By putting the can, with the cover screwed on securely, aside for 24 hours, the spores will germinate and become organisms like the parent cell. These are killed by reheating at the same temperature for 15 minutes. By repeating the process so that the food in the cans has been heated 3 times after intervals of 24 hours, the micro-organisms are killed, all the spores having developed into micro-organisms.

The covers must be loosened while the cans are in the boiling water and screwed down tightly at all other times. This process is called fractional or intermittent sterilization. By this method the fruit and vegetables retain their natural shape, color, and flavor.

Suggestions For Home Application