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Introduction to Home Canning

© Vic Ferri

Canning, though not as simple and quick as freezing(which we discussed last month) is the traditional way to preserve fruits and vegetables and makes for a very rewarding experience for many people. It is hot, heavy and time consuming work but there comes a sense of pride from safely canning your own special or traditonal recipes. Home canned recipes also make for terrific gifts.

The basic process involves placing food in jars and then heating them to a high enough temperature to destroy microoganisms. This process also drives air out of the jar and a vacuum seal is formed during cooling.

Whenever you do canning, you should be aware of the possibility of spoilage(contamination) and thus it is very important that you follow the canning directions very carefully and accurately. Canning is very safe so long as you do it right. In fact, when done right, canning is considered by the USDA as the safest method for preserving food.

There are two basic methods of safe home canning - the boiling water bath method and the pressure canner method.

Boiling Water Method

Boiling water is safe for preserving high acid foods - in other words, fruits, which are used to make jams, jellies, preserves, etc. Tomatoes which are somewhat acidic, are often preserved this way as well. The food is placed in jars which are heated completely covered with boiling water and cooked for a specified amount of time.

Pressure Canning Method

The pressure canner method is used for low acid foods - which is most foods - like vegetables and meats. These foods must be processed in a pressure canner at 240 degrees F. This temperature can only be reached with the pressure method and is necessary to kill the spores of the microorganism clostridium botulinum(which can survive the boiling point temperature) These spores grow well in canned low acid foods(but not in high acid foods)and they produce the deadly botulism poisons.

Tomatoe Notes

When canning tomatoes using the boiling water bath method, a little citrus acid or lemon juice is usually added to the recipe to ensure the acidity level is high enough. Tomatoes have a pH value close to 4.6 which marks the dividing line between low acid and high acid foods(the lower the ph value, the higher the acidity)

Equipment Needed

For the boiling water method, all you basically need is a large heavy pot - large enough so that the jars of food can be completely covered with boiling water. However, it would be much more convenient if you had two extra pots - one to use to heat the jar lids and rings, and another to heat the glass jars.

The copyright of the article Introduction to Home Canning in Edible Gardens is owned by Jill Florio. Permission to republish Introduction to Home Canning in print or online must be granted by the author in writing.