The Basics of Home Canning and Preserving of Foods

Home Canning Basics

Canning is the process of preserving food by heating the food to a high enough temperature and length of time to interrupt the normal spoilage and decay process cycle of food.

In other words, you want to control the microorganisms, enzymes, oxygen and moisture loss in foods so that they last longer, taste better, and provide nutrients as though they were fresh.

This is all done by boiling the food ingredients in the canning jars at a very high temperature.

Watch Out for Wax!

If you intend to buy "fresh" vegetables at your local grocery store, please keep in mind that most grocery stores have wax on fruit, such as watermelons, apples, tomatoes, turnips, squash, tangerines, cucumbers, beets, onions, papayas, and rutabagas.

Typically it is made of beeswax, but not always.

However, often the wax is combined with a fungicide, to prevent mold problems during shipping and while on display.

The Proper Temperature

In order to destroy the yeasts, molds and some bacteria in high-acid foods the temperature needs to reach 180 - 212°F. This is the boiling point at sea level.  For high-acid foods you can use a water-boiling canner.

The temperature to kill bacterial spores in low-acid foods is 240°F, which can only be done by using a steam-pressure canner.

The Quality of the Foods

In order to have the highest quality canned goods, you must start with the highest quality produce.  Use fruits and vegetables from a garden or famer's market.

It is important to remove any damaged or diseased parts of your fruits and vegetables in order to remove as much mold, yeast, and bacteria as possible. This helps you because most canning recipes are for quality foods, not for damaged or diseased produce, which would effect the processing time.

Plus the food just looks better sitting in the jars!

The Times Have Changed!

The times have changed a lot since the time of our our grand parents.  Those old pressure cookers that used to explode in the kitchen have been replaced by modern steam-pressure canning pots.

These new fangled kitchen gadgets are not nearly as dangerous.

You can now can your vegetables in relative safety. :)


Botulism is the deadly paralyzing food toxin which is caused by the bacterium Closteridium botulinum. This bacteria is easily killed by boiling, however the spores of the bacteria are not completely killed at 212°F.

It is due to these spores in particular that you should use a modern pressure canner.

Botulism can cause paralysis, cardiac and respiratory failure.

Acidity of foods helps determine the type of heat processing or home canning required for safe preservation.
Acidity of foods helps determine the type of heat processing or home canning required for safe preservation. | Source

The Acidity of Foods Determines the Process

All foods fall within two areas on the pH Scale, which is somewhere between being strongly acidic or strongly alkali (not acidic).

The level of acidity determines the method of canning, also known as processing, that is to be used. When it comes down to the method of processing, it really is a matter of either using a boiling-water canner or a steam-pressure canner. As mentioned above, this is due to the temperatures that boiling and steam-pressure can reach.

High-acid foods should be processed using a boiling-water canner .

Low-acid foods are to be processed using a steam-pressure canner .

It's that simple!

The Best Books on Preserving Foods by Canning

There are many good books on canning, but I will only list the great ones. 

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Comments 2 comments

ChristineVianello profile image

ChristineVianello 5 years ago from Philadelphia

Very interesting. I think I would be scared of canning certain foods, but would love to try it.

medor profile image

medor 5 years ago from Michigan, USA

Very nice... just getting back into canning again. Always used the Ball Jar books for canning information and times... have been canning or helping with canning (with my mom and grandmother) most of my life... nice job. thanks for sharing.

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