What's
pressure canning?
Pressure canning is the best method for safe food preservation. Safe means that you kill all harmful bacteria during canning. So also the botulism bacteria. Because canning kills harmful bacteria, you can keep the food you preserve in this way for at least a year. Just on the shelf and not specifically in a freezer.
Pressure canning works with a special pan, a pressure canner. A pressure canner resembles a pressure cooker. There is an important difference: with a pressure canner you can see on the pressure gauge how high the pressure is that has built up inside the canner. You need the information about the pressure for safe conservation.
If you want to preserve food with a low acidity, such as vegetables, meat and fish, pressure canning is the only safe method.
You place the jars containing the food you want to preserve on a special base plate in the pressure canner. Then fill the canner with 3 liters of water. Because a pressure canner works with steam, the jars do not have to be largely submerged in water, as is the case with preserving.
Then close the canner. The canner is supplied with a pressure weight which is intended to close the steam valve. Do not put the weight on the steam valve at the start.
You place the pan on the stove and choose the highest setting. The heat fills the canner with steam from the inside. This pushes all the air out of the canner. As soon as the water in the canner boils, steam will come out of the valve.
After 10 minutes, the canner is evenly filled with steam from the inside. Then it is time to place the pressure weight on the valve. Now the pressure in the canner increases and the temperature rises to above 115 degrees Celsius. You need that temperature to kill all bacteria.
After the preserving time appropriate for the food in your canner has passed, remove the canner from the stove. During cooling, the jars automatically create a vacuum. It works like this: while heating, the contents of the pot expand. This pushes all the oxygen out of the pot. When the jar cools, the contents shrink again, pulling the lid down and creating a vacuum. This ensures that the jar is sealed airtight and your preserved food remains stable.
How works
pressure
canning?
Botulism and
preserve
What is botulism and why is it dangerous?
Of all the harmful bacteria that exist, the Botulism bacteria are often discussed in combination with food. That's not easy. Botulism is a serious, potentially life-threatening disease caused by the bacterium with the charming name Clostridium Botulinum. Botulism can cause paralysis and even lead to death. The best-known form we know is food-related botulism.
This occurs when food becomes contaminated with the bacteria and is then not stored safely. Food that is not properly preserved can be an ideal place for the bacteria.
The bacterium that causes botulism is in principle not dangerous to humans and animals. After all, the bacteria are everywhere in the soil and in water. Normally that is not a problem. The problem is that under the right conditions the bacteria can produce toxins. These toxins can cause paralysis and can even be fatal.
When is there a risk of botulism?
The Botulism bacteria thrive in conditions with little oxygen, moisture and low acidity. Actually exactly the conditions as in a vacuum-sealed pot with vegetables, for example.
With pressure canning you cook under pressure. This causes the temperature to become so high that it kills all bacteria. So, for example, if you have preserved a jar of beets in your pressure canner and you open it after a year, you can use it for a salad, for example. So you don't have to cook it again before you can safely eat it.
That's different from when you weck vegetables. When you open your jar after a year, you still have to cook the food for at least 10 minutes to neutralize the toxins. And even then you haven't killed all the bacteria.
Pressure: the pressure gauge and the pressure weight
When the lid is on the pressure canner, the canner is completely closed. When the water starts to boil, the canner fills with steam. This causes the pressure in the canner to increase. This in turn causes the temperature in the canner to rise to above 115 degrees. And at that temperature all bacteria are killed. The amount of pressure you need to build up to be able to pressure can something safely varies a bit at what altitude you live.
If you want to achieve the correct temperature within your pressure canner, you must take into account where you live in relation to sea level. Water boils at a lower temperature as you go up. A lower cooking temperature is not effective enough to kill most bacteria.
The Netherlands
The minimum pressure you need in the Netherlands to can can safely when you work with a canner with a pressure weight is 10 PSI. If you work with a canner with a pressure gauge, it is recommended to work with 11 PSI.
The CanMate has both so you can safely preserve at 10 PSI.
Outside The Netherlands
If you live in a place higher than 300m above NAP (= New Amsterdam Level or sea level), it is important that you work with the pressure required for the altitude where you live. Below you will find a table showing which pressure to use. For example, if you live at 800 meters, you must increase the pressure in your canner to 15 PSI if you have a canner with a pressure weight and to 12 PSI if you have a pressure gauge. The CanMate has both so you can safely preserve at a pressure of 12 PSI.
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Pressure
Canners with a pressure weight and/or a pressure gauge
There are two different types of pressure canners:
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the canners with only a weighted gauge
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and the canners with a pressure weight and a pressure gauge (dial gauge)
A canner with only a pressure weight works with a weight on the valve of the canner. The weight vibrates with the right pressure. If your canner only works with a pressure weight and has a 10 psi weight, this weight will vibrate and hiss at a pressure of 10 psi. If you have a canner with a 15 psi, it will vibrate and hiss at a pressure of 15 psi.
How high you live in relation to sea level determines how much weight you have to work with. As soon as the weight starts vibrating and hissing, you know that your pressure canner is at the right pressure and that you can start the timer.
Our CanMate has a pressure gauge (dial gauge) that allows you to read the pressure in the canner. You can easily see when the correct pressure has been reached. It is important to have the pressure gauge calibrated every year so that it continues to accurately indicate the pressure. You can have this calibration done at companies and you can use Google to see which companies offer this service in your area.
Our CanMate Presspan 22 qt is equipped with both a pressure gauge and a pressure weight. Our latest version comes with a pressure weight for 10 and for 15 PSI.
The advantage of having a pressure weight is that it is no longer necessary to calibrate the pressure gauge every year. You just wait for the weight to start hissing and turning on you. Then you immediately know that the correct pressure has been reached. An additional advantage of a pressure weight is that it also hisses when you are a little further away. So you don't have to keep checking the meter.
Get going
If you are going to use your pressure canner, you first choose your recipe. You can work with tested recipes from the USDA. This is the United States Department of Agriculture, which is also concerned with food safety. This is the link to the recipes:
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Of course in English and they work with American sizes
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There is also a very good Dutch alternative. If you want recipes for pressure canning that have been translated into Dutch and use Dutch sizes and quantities, you can go to Boerderij in een rijtjeshuis. The costs are 5 euros.
Step-by-step
pressure canning
01
After you have chosen your recipe, you can get started. Make sure your pots are clean. It is not necessary to sterilize first because this is done during pressure canning.
Clean pots
02
Fill the jars
Get your jars ready to be filled. It is most convenient to do this with a funnel with a large hole. This ensures that the edges remain clean. Leave the recommended space at the top of the pot. If all goes well, this should be in your recipe. On average, that is 2.5 centimeters.
03
Roer dan met een chopstick in de pot. Daarmee verwijder je de luchtbelletjes. Het is belangrijk dat er zo veel mogelijk luchtbelletjes uit de pot zijn. Lucht kan ervoor zorgen dat je product in je pot langzaamaan bederft. Daarom willen we luchtbellen al zo veel mogelijk verwijderen. Tijdens het pressure cannen wordt vanzelf de rest van de lucht uit de pot gedrukt.
Remove air bubbles
04
Screw the lid on
Then clean the edges of your pot thoroughly. If you have used a good funnel, you will hardly have to clean. If you work with food that is not greasy or sticky, a clean dishcloth with water is often sufficient. If you work with greasy or sticky food, vinegar can help you degrease the edge. Then take a clean dishcloth, put some vinegar on it and then pull it along the edge.
It is very important that the edge is clean, otherwise the lid will not adhere to the glass edge. Then screw the lid on finger tight, so not super tight. If you tighten it very tightly, the remaining air can no longer be pushed out during pressure canning. Air will then remain in your pot and you don't want that.
05
When your jars are ready for canning, fill the canner with 3 liters of water. It doesn't matter how many pots you have in there, it's always 3 liters of water. Be careful: if your jars are hot, put hot water in your canner. If your pots are cold, put cold water in them. Then place your jars in the canner.
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Check whether the ring in your lid is properly seated and place the lid on the canner. Turn your heat up very high and wait until you hear steam coming out of the valve. How long this takes varies per hob and whether you started with cold or hot pots. As soon as power comes from the valve (and the pin in the right handle of the CanMate has risen), turn the heat down a bit. You want to avoid losing too much moisture from the canner, which could cause your canner to boil dry.
Fill the canner
06
Steam for 10 minutes and place a weight
Then set your kitchen timer for 10 minutes. During those 10 minutes, the canner fills completely with steam and pushes the air out. After 10 minutes you can place your weight on the valve and the pressure can slowly build up.
07
If you work with a canner with a pressure gauge, keep a close eye on your pressure gauge until it indicates the correct pressure for you. If you work with a canner with a pressure weight, wait until your weight starts to vibrate. Once you have reached the correct pressure, set the timer for the desired preserving time. You can probably find this in the recipe. You really should only turn on your timer when the correct pressure has been reached.
Building pressure
08
Cool and empty
Once your timer has gone off, remove your canner from the stove and release all the pressure. If your canner has a pressure gauge, you can see when the gauge is completely at zero. If you only have a canner with a pressure weight, the pressure has run away when you no longer hear any hissing at all.
Now you can take the weight off. Wait another 10 minutes before removing the lid. Then wait another 10 minutes and then remove the jars from the canner with the glass tongs.
You want to cool down so gradually that you don't expose the jars to a big temperature difference. The contents of the jars are still very hot and when it is that hot, the contents expand. If the area around the jar suddenly becomes much colder by quickly removing the jar from the canner, the hot contents will want to push out. This causes you to lose moisture from your jars and some can get between the glass edge and the lid, causing the vacuum to not work properly.
So let your canner cool down slowly and wait 10 minutes between each step to prevent it from cooling down too quickly.
Even if you do this carefully, you may lose some of the contents of your jar. As long as more than 2/3 is left in the jar and the jar has been evacuated, you can still store it in the pantry. If you lose more, it is important to place this jar in the refrigerator after cooling and eat it first. Even when the pot has been vacuumed.
09
Then let your jars cool for 24 hours and then check whether they have been vacuumed properly. If you work with mason jars, remove the ring and check whether the lid remains firmly attached. For example, you can lift it by the lid and if the lid remains in place, the vacuum is strong enough.
If you work with reusable screwdriver jars, you can check whether the cap has been sucked in and whether it no longer makes a sound when you press it.
If you work with preserving jars, you can check whether the lid stays in place when you lift it by the lid without a bracket or clamps.
If your vacuum test went well, the jar can go to the pantry. It is recommended to eat the contents of the jar within a year.
Pantry
Pressure can times
