Pressure Canning and Water Bath Canning

You may have heard the terms "water bath canning" and "pressure canning" thrown around in the canning world, but do you know the difference? There is a difference between these two canning methods, and you need to know what it is!

Pressure Canning vs. Pressure Cooking

First, it's important that you understand that a 'pressure canner' is not the same as a 'pressure cooker'.

Pressure cookers are used to cook food in a very short period of time. The pressure cooker is a tightly sealed pot that cooks foods at much higher temperatures than the standard boiling point. It builds pressure and steam inside, which results in dramatically less cooking time.

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Pressure canners are designed specifically for canning foods, and they work in a similar way. The pressure canner is a sealed pot that builds up pressure and steam, and reaches 240* F. This high temperature kills all the bacteria and botulism inside the jars of food, which safely preserves them.

Ordinary pressure cookers should not be used for canning, since they don't have the capability to kill the bacteria and botulism spores inside the jars.

However, there are some pressure cookers that are specifically made to double as a cooker and a canner all in one. These are fine to use, since they are designed for this purpose. You just don't want to use an ordinary pressure cooker for your canning.

Pressure Canning vs. Water Bath Canning

There are two methods that are used in canning. One is pressure canning, and the other is water bath canning. If you plan to can fruits, vegetables, and meats, you will be using both ways!

Pressure canning is basically the process of putting your filled jars in a pot of water. An air-tight lid with a rubber seal is placed on the top of the pot to prevent any air from coming or going. This allows pressure to build up inside the pot, which causes the water and food inside the pot to come to a much higher temperature than just boiling. (The boiling point is 212* F. Home pressure canners get up to 240*F.) This high temperature kills the really tough bacteria that is found in certain foods. You will need to buy a pressure canner from the store in order to can using this method. Most pressure canners can also be used to do water bath canning - all you do is leave off the lid.

pressure-canners Is it safe? Why does my pressure canner always sound like it's about to explode?

Pressure canners are safe as long as you use common sense. For instance, NEVER attempt to open the lid of your canner when it is in the middle of processing your jars! The extremely hot water will explode everywhere and could severely burn you. Check with your user's manual that came with your pressure canner to see specific safety precautions. While your jars are being processed, your pressure canner will make a lot of noise. It will rattle, puff, steam, and hiss - but this is completely normal. Remember that there is a lot of pressure building up inside; so a little bit of noise is perfectly understandable!

Water bath canningis submerging your jars of food into an open pot of water and boiling them for a certain amount of time. Water bath canners do not have a lid, which means they will not build up steam and pressure, and will not be able to reach 240*F like pressure canners. This is fine if you are only canning fruits this way; anything else, like vegetables and meats, must be pressure canned.

You can buy a separate water bath canner, or you can use your pressure canner as a water bath. In this case, you should simply leave the lid off. Jars should be completely submerged in water when you use the water bath method. When you use the pressure canning method, however, your jars do not need to be completely covered with water. Your owner's manual will have more specific directions on this.

What's the difference between pressure and water bath canning? Why can't I just stick with one method?

The answer is simple - bacteria.

Certain foods have a high level of acid in them. Acid kills bacteria. Foods with lots of acid in them don't require much heat to successfully kill of all the bacteria found in them. These foods (usually fruits) are canned using the water bath canning method, because they don't need a lot of heat to get rid of all the bacteria. Boiling fruits for 10 or 20 minutes will usually take care of it all.

But foods like vegetables and meat have a much lower-acid content, making it easy for botulism spores to grow and multiply, which produces a deadly toxin. Only temperatures of 240* F, which only pressure canners can reach, will kill these dangerous spores.

Low acid foods, such as meats (poultry and beef), seafoods, vegetables, or dairy, should always be pressure canned. It is the only way to safely preserve them.

alt text Foods that are processed this way are usually heated up for a much longer time than water bath canned foods.

You also need to make sure that you adjust the processing time for your specific altitude, as this makes a very big difference in safely canned foods! A jar of jelly might only be heated in your water bath canner for 10 minutes, while a jar of meat might be processed in a pressure canner for 90 minutes. It takes a lot more time and a lot more heat to kill the bacteria found in veggetables and meat.

How do I know which foods get canned using which method?

First of all, your recipe will almost always tell you. If you're canning something that was prepared using a recipe, all you need to do is look at the recipe and follow the directions. (However, be aware that canning recipes prior to 1990 will probably give directions that are now known as unsafe, such as water bath canning vegetables. Sometimes they will not even tell you to process your jars at all. Do not use these recipes.)

If you're canning something that doesn't use a recipe (like green beans), just remember that all fruit gets water bath canned, and anything else should go in the pressure canner. Only fruits or jams should ever be water bath canned. This is because fruit has a high acid content, and this acid will help kill bacteria inside the jar. Vegetables and meats must be pressure canned, because of their low acid content - they need more heat to help them out!

Water bath vs. open kettle

water bath canning

Although old-timers still swear by it, the open kettle method is a completely unsafe canning method. Open kettle canning is done by boiling the food you want to can, filling the jars with hot food, placing lids and rings on the top, and then leaving them on the counter to seal on their own. This method does not use any kind of canner and does process the jars.

Although the lids will 'pop' and techinically seal by themselves due to the temperature of the food, you are taking a serious risk by not killing all of the bacteria in the jars. Only high boiling temperatures will kill bacteria. And even if you use hot jars, you still will not achieve the temperature needed to kill the bacteria and botulism spores inside! This is the reason you shouldn't put lids on your jars of hot jam until you are immediatly ready to process them. They will seal on their own if you are not quick.

"Why can't I use the open kettle method? Grandma never got sick!" True, but than again, people have gotten sick from it. Failing to wear a seatbelt just because your grandma never wore one and still lived is just as ridiculous. Unless you are willing to take the risk of food poisoning or botulism, I would highly recommend only using the water bath or canning method!

Just as you should never use that open kettle method, you also need to be careful of how you use the water bath canning method. Only fruits, jams, and jellies (as long as they do not contain dairy) should be water bath canned. All the rest, like meats, vegetables, dairy, or seafoods, should always be pressure canned.

go from Water Bath Canning to Pressure Canning

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