Canning 101

Preserving food is all about keeping any creepy crawlies in the food in check. There are a number of ways of stifling their growth, cold temperatures being one of the easiest. The ease with which we store perishable foods these days was only a fantasy in yesteryear. Refrigeration and freezing are by far the easiest way to retard bacterial and fungal growth in food.

What are some of the others? Well, it's all about making an inhospitable environment for the critters. An environment that it too dry, salty, fatty, sugary, acidic, anaerobic, or hot is considered hostile to most microbes. Canning commonly uses the last four. Jams and jellies, for instance, are preserved by the amount of sugar they contain (have you ever noticed how long an open jar of jelly lasts in the fridge?).

There are two main types of canning: water bath and pressure canning:

Water bath canning requires an acidity of 4.6 or lower to help keep microbes in check. This acidity means that the jars of food do not have to be processed to as high a temperature. Water bath canning involves canning both acid and acidified foods. Acid foods are naturally high in acid and include most fruits like peaches, pears, and apples. Acidified foods are foods that have to have acid added to them in order to make them safe. Pickled goods are all acidified. If you are new to canning, you want to be sure to always follow tested recipes. I have been canning for over 15 years now, so I have started making up my own recipes, but to be sure they are safe and under the 4.6 pH requirement, I use a pH meter (see my aStore).

Pressure canning involves using pressure to increase the boiling temperature within the kettle. When you want to can something that is not acidic, you have to process the jars to a higher temperature; a pressure canner provides this ability. All modern pressure canners have very good safety valves, so you don't have to worry about you canner exploding if you don't know what you are doing (always a good thing to know!).

There are a few general things you need to know about supplies. The major components include canning jars (don't use other types of jars as they may not hold up to the rigors of the hot pot...), canning lids and bands, jar tongs, and a canner (either a large kettle/stock pot or pressure canner depending on what type of canning you are doing).


The basic procedures for canning are pretty standardized. So that I don't have to write them over and over again whenever I post a canning recipe, I will give those instructions here:


Water Bath Canning

1. Prepare food as instructed.


2. Wash jars in hot, soapy water. They do not need to be sterilized.


3. Prepare canner. This means filling and starting to heat the water for a water bath canner (just bring to a simmer). Remember that your jars will displace a large amount of water. Take this into account when filling your pot up so that your jars will be covered by at least one inch of water.


4. Have jars set out along with your canning funnel and bands. Heat up enough water to soak the canning lids. This process softens up the wax rim and allows them to sit better on the jar, making a better seal.


5. Fill jars as instructed leaving the proper head space. This space should be defined in the recipe. Leaving the proper head space is important in obtaining a good seal. It typically varies between 1/4 inch and 1/2 inch for water bath canning.


6. Use a plastic knife or wooden skewer to poke down the sides of the jars to release any trapped air bubbles.


7. With a clean sponge or rag, wipe down the top rim of the jar so that the lids can form a clean seal.


8. Place seals onto jars and screw on with the bands. Bands only need to be hand tight. Do not over tighten!


9. Using your jar tongs, place jars in your canner. Turn the heat up once the jars are in the water. Bring the water to a slow boil. Do not start counting your processing time until the water boils. Then process for the time specified in the recipe. Some recipes use a "pasteurization" process that uses a lower temperature. If this is the case, use a thermometer to keep track of the temperature.


10. When the time is up, turn the heat off and let the jars sit in the water for five minutes before removing them. While this step is not always needed, for certain items, pulling them out of the canner right away can cause the filling to come oozing out of the jars. This can be very messy and can lead to bad seals. While you are usually safe to pull jams, jellies, pickles, and fruit in syrup out immediately, I always figure better safe than sorry.


11. Remove jars from the water and set on a towel lined counter. Let jars sit undisturbed to cool for 6-8 hours. As they cool, you should hear the tell-tale "pop" as the jars vacuum seal.


12. Once the jars are cool, carefully remove the bands and wash the jars, if necessary. It is usually best to store canned goods without the screw band. Keep jars in a cool, dark place. Always check the seals before you use the food. "If in doubt, throw it out!"

Pressure Canning

1. Prepare food as instructed.


2. Wash jars in hot, soapy water. They do not need to be sterilized.


3. Prepare canner. With a pressure canner, you will want to follow the instructions that come with your canner for its preparation. Because pressure canners use steam to heat the jars, you need to use the specific amount of water for your canner.


4. Have jars set out along with your canning funnel and bands. Heat up enough water to soak the canning lids. This process softens up the wax rim and allows them to sit better on the jar, making a better seal.


5. Fill jars as instructed leaving the proper head space. This space should be defined in the recipe. Leaving the proper head space is important in obtaining a good seal. When pressure canning, this head space is typically 1 inch.


6. Use a plastic knife or wooden skewer to poke down the sides of the jars to release any trapped air bubbles.


7. With a clean sponge or rag, wipe down the top rim of the jar so that the lids can form a clean seal.


8. Place seals onto jars and screw on with the bands. Bands only need to be hand tight. Do not over tighten!


9. Using your jar tongs, place jars in your canner. Close the canner and prepare it for the proper pressure. This procedure will vary depending on your canner, so follow the directions that came with your canner.


10. When the time is up, turn the heat off and let your canner cool down naturally. This can take a while. Do not try to speed the process up! Let the pressure dissipate naturally.


11. Remove jars from the canner and set on a towel lined counter. Let jars sit undisturbed to cool for 6-8 hours. As they cool, you should hear the tell-tale "pop" as the jars vacuum seal.


12. Once the jars are cool, carefully remove the bands and wash the jars, if necessary. It is usually best to store canned goods without the screw band. Keep jars in a cool, dark place. Always check the seals before you use the food. "If in doubt, throw it out!"

This is a very abbreviated set of instructions for canning. I highly recommend that you invest in The Ball Bluebook for a more detailed set of instructions (see my aStore). It is really necessary, I think, to have a good reference around. I've been canning for a long time, and I always seem to be checking some bit of information in mine. If you have any troubles or questions, just let me know!