Water Bath Canning and Pressure Canning: Explained

Master water bath canning and pressure canning and there'll be nothing you can't can.

| July 14, 2011

  • Pressure Pot
    Don't let a little steam and boiling water scare you. Pressure canning and water bath canning are safe methods to preserve your food. Learn how with this excerpt from the USDA Complete Guide to Home Canning.
    Photo By Fotolia/James Steidl
  • Food Acidity Chart
    This acidity chart tells you which foods are high in acid and which are low. High-acid foods can be canned with a water bath canner and/or a pressure canner, while low-acid foods must be canned with a pressure canner.
    Illustration From United States Department of Agriculture
  • Water Bath Canner
    Water bath (also called boiling water) canners are good for quickly and safely canning high-acid foods such as peaches, strawberries and just about any other fruit. As noted in the illustration, make sure to leave extra airspace at the top to maintain a brisk boil.
    Illustration From United States Department of Agriculture
  • Pressure Canner How-To
    Pressure canning, like any other task, is perfectly manageable when broken up into steps. Follow the steps above to safely can any low- or high-acid foods.
    Chart From United States Department of Agriculture
  • Example A Process Times
    Processing times for food depends on the style of packing (hot or raw/cold), the type of canner (water bath or pressure) and the food itself. Above, process times for peaches canned with a boiling-water (water bath) canner are given. Note the increase in process times as the altitude changes.
    Chart From United States Department of Agriculture
  • Example C Process Times
    A weighted-gauge pressure canner allows pressure to build up to a desired level before releasing steam to prevent the pressure from rising any higher. Above, the USDA lists the process time and desired pressure for canning peaches.
    Chart From United States Department of Agriculture
  • Example B Process Times
    The USDA has process times for all types of canners. Here, the process time for peaches in a dial-gauge pressure canner is listed. Compare this time with the time for peaches processed in a boiling-water canner.
    Chart From United States Department of Agriculture

  • Pressure Pot
  • Food Acidity Chart
  • Water Bath Canner
  • Pressure Canner How-To
  • Example A Process Times
  • Example C Process Times
  • Example B Process Times

If you’re new to canning, deciding between water bath (boiling-water) canning and pressure canning can be a difficult task. Water bath canning seems easier, and works for fruits and pickles, but can’t be used for low-acid foods such as red meat and some vegetables. Pressure canning, on the other hand, can be intimidating to novices, particularly if you’ve heard the old tales of exploding canners. With this helpful excerpt from the United States Department of Agriculture's Complete Guide to Home Canning, you'll learn the difference between pressure canning and water bath canning to decide which is best for you. Use this and our other canning resources to stock up after your harvest.

The following is an excerpt from the USDA Complete Guide to Home Canning covering how to can carrots.

Food Acidity and Processing Methods 

Whether food should be processed in a pressure canner or boiling-water canner to control botulinum bacteria depends on the acidity of the food. Acidity may be natural, as in most fruits, or added, as in pickled food. Low-acid canned foods are not acidic enough to prevent the growth of these bacteria. Acid foods contain enough acid to block their growth, or destroy them more rapidly when heated. The term “pH” is a measure of acidity; the lower its value, the more acid the food. The acidity level in foods can be increased by adding lemon juice, citric acid, or vinegar.

Low-acid foods have pH values higher than 4.6. They include red meats, seafood, poultry, milk, and all fresh vegetables except for most tomatoes. Most mixtures of low-acid and acid foods also have pH values above 4.6 unless their recipes include enough lemon juice, citric acid, or vinegar to make them acid foods. Acid foods have a pH of 4.6 or lower. They include fruits, pickles, sauerkraut, jams, jellies, marmalades, and fruit butters.



Although tomatoes usually are considered an acid food, some are now known to have pH values slightly above 4.6. Figs also have pH values slightly above 4.6. Therefore, if they are to be canned as acid foods, these products must be acidified to a pH of 4.6 or lower with lemon juice or citric acid. Properly acidified tomatoes and figs are acid foods and can be safely processed in a boiling-water canner.

Botulinum spores are very hard to destroy at boiling-water temperatures; the higher the can­ner temperature, the more easily they are destroyed. Therefore, all low-acid foods should be sterilized at temperatures of 240 to 250 degrees Fahrenheit, attainable with pressure canners operated at 10 to 15 PSIG. PSIG means pounds per square inch of pressure as measured by gauge. The more familiar “PSI” designation is used hereafter in this publication. At temperatures of 240 to 250 degrees, the time needed to destroy bacteria in low-acid canned food ranges from 20 to 100 minutes. The exact time depends on the kind of food being canned, the way it is packed into jars, and the size of jars. The time needed to safely process low-acid foods in a boiling-water canner ranges from 7 to 11 hours; the time needed to process acid foods in boiling water varies from 5 to 85 minutes.

Norm
8/30/2019 4:56:14 PM

As someone who has canned for most of my life, some of the advise is bunk from someone who has never spent a day in a hot kitchen canning. My mother had one with a gauge and you had to stay on your toes to make sure the pressure didn't get to high. I have never spent 10 minuets venting a pressure cooker! Here's how my mother done and how we have done it for ever. You put enough water in the cooker to be over the jar rack in the bottom of the canner. Then the cooker is brought to a hard boil. What ever you are canning should be pre heated or have hot water poured in the jar such as green beans. Place the lids on and place in the canner. Place the lid on the canner and than place the weight for what you are canning. When the weight starts to rock, you turn the heat down to get 4 to 6 rocks per miniutes depending on what you are canning. Time also depends on what you are canning. Tomatoes are at 5 pounds till it starts to rock and turn off heat. Green beans are 10 pounds rock 4 times a miniute for25 minutes and turn off heat. We have never had botulism problems and very few non seals. I have food right now in my basement that is from 2016 and I have know problem eating it. I under stand why people are so cautious because of liabilities but it get stupid some times. Happy canning!


george
7/5/2019 12:29:50 PM

I enjoy reading these articles. Unfortunately, the last few times when I press 'Continue Reading' it goes nowhere. Can anyone help me?


chiweenie47
9/17/2017 5:37:17 PM

i am going nuts trying to find a way to do my hot water canning, like I always have, on top o fthe stove but the new stoves with the glass tops say NO CANNING. so I thought in induction burner would work, so I bought one thinking it would heat the water to boiling and keep it that way and now it says no canning. the kitchen I have has the glass topped stove and I cannot find one that matches my new set of appliances. i usually only make jellies, Jams, and canned fruit like peaches, pears and such. it seems if the jars are under water which is boiling for the amount of time suggested it should seal them and kill any germs, but the instructions say NO CANNING> what should I do?







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