This is the second portion of my information sharing on food preservation. Since there was so much information, I thought it best to divide it into sections. So, a little about canning…
This is where people get nervous. They’ve heard how pressure canners have exploded in the past. Honestly, with the newer canners (and cookers), if one explodes, it was probably altered and became unsafe. There are so many safety features on the newer ones that it is rare something goes wrong.
As mentioned in a previous post, there is a difference between pressure canning and water bath canning. Let’s look at both:
Water bath canning is for high-acid foods and can usually be processed using boiling-water. High-acid foods are foods with a pH of 4.6 or less. High-acid foods include things like fruits (except figs) and most tomatoes. Low-acid foods should never be processed using this method since the temperature to kill Clostridium botulinum cannot be reached using the water-bath canning method. Remember, Clostridium botulinum is the bacteria that causes botulism; a severe form of food poisoning that can be life threatening.
From my previous post:
Water-Bath Canning: Jars are filled with a high-acid food, lids applied, and then completely submerged into water. There should be about 2 inches of water covering all jars. Bring the water to a boil and process for the suggested amount of time. Once finished, the jars can be removed from the water-bath and set out to cool and lids to seal. After 12 – 24 hours and jars have completely cooled, check for failed seals. If adequately sealed, remove the rings (or bands), and clean the outside of the jars. These should be shelf-stable for several months to even years.
Processing steps: Add water to your canner and turn it on to start heating the water. Following your recipe, fill the jars to the suggested headspace. To prevent jar breakage, if cold packing, add hot liquid to the jar. Remove any bubbles and verify the headspace is adequate – add more food or liquid if needed. Wipe off the rims of the jars and then run a clean, dry finger along the rim to make sure there are no nicks or chips that could prevent the lid from sealing. Put the band on finger tight. Make sure you always use a rack or towel in the bottom of the canner to prevent damage to your jars. Carefully lower the jars into the canner using a rack or jar lifter; ensure they are covered by 1-2 inches of water, adding additional water if needed. Start your timer once the water begins to boil (with a lot of water you may need to put a lid on the pot). Most recipes you’ll find are based on elevation 1000 feet or below. However, according to the Ball Guide to Preserving, the processing time should be adjusted for altitude. The following information is based on the Ball Blue Book guidelines:
| Altitude in Feet | Increase Processing Time |
| 1,001 – 3,000 | 5 Minutes |
| 3,001 – 6,000 | 10 Minutes |
| 6,001 – 8,000 | 15 Minutes |
| 8,001 – 10,000 | 20 Minutes |
Types of food you can preserve using water bath canning include, but are not limited to, jelly, jam, salsa, pickles, etc. Remember, it is not safe to use the water bath method to preserve low acid foods.
Pressure canning is what most people are afraid of. There have been horror stories of people being injured from canners exploding. Honestly, newer canners have so many safety features, it is rare that one will cause harm if used properly. This method is to process low-acid foods that have a pH greater than 4.6. Most cases of botulism are from improperly processed home foods and a majority are because low-acid foods were processed using the water-bath method. Low-acid foods must be pressure canned and the pressure used should be adjusted for altitude above sea level.
From my previous post:
Pressure Canning: The only canning method suggested for processing low-acid foods. The steam inside the canner builds and can reach a temperature of at least 240O F. This temperature is sufficient to destroy harmful bacteria, spores, and neurotoxins. A weighted gauge or pressure gauge is used to ensure the correct amount of pressure for the elevation is reached. If using a dial gauge, it must be tested and calibrated annually. A weighted gauge does not need to be tested.
As I mentioned previously, you can use either of the following methods to fill your jars:
- Cold or Raw Pack: Filling jars with raw, unheated food before processing. Food can be chopped or prepped but is not pre-cooked or heated.
- Hot Pack: Filling jars with hot food. Sometimes the food is boiled in water or broth. There may be times food is completely cooked and then put into jars before processing. Food still needs to be processed for the amount of time and/or pressure suggested for safety.
So how do you pressure can? It’s easy but it will take a while (meats process for 75 – 90 minutes depending on the size jar). Until this year, I had never canned anything with meat, but if done properly, it will last for quite a while. In fact, yesterday, I ate beef stew I canned 5 months ago. It was delicious and since I’m not sick today, I must have done it correctly!
Many people have gas stoves and if you do – lucky you. I don’t; mine is glass top. If you have a glass top stove find out how much weight it can hold. Mine is rated for 50 pounds and since my canner is 16 quarts, even full, it’s not quite 50 pounds. Some people use outdoor (propane) cookers, but you need to be careful with those. Find out the BTU output of the cooker. Most canner manufacturers state less than 12,000 BTUs to prevent damage to the metal. I haven’t used a propane cooker, but it would be really nice if I could find one to free up my stove.
You don’t have to sterilize your jars or lids, but your jars should be clean and not cold. I usually, run mine through the dishwasher or wash them in hot, soapy water. If hot packing, to keep the jars warm, I will turn my oven on the bread proof function and then put them in there until I am ready for them. If you don’t have a bread proof setting, just turn your oven on to the lowest setting to heat up and then turn it off. You’re just trying to keep your jars from getting too cold. If you’ve just washed them in your dishwasher, just keep them in there until ready to use, they’ll be warm enough. My lids? I just wash and set aside. They don’t have to be hot, but many people like to keep them in hot water until ready to use. So why don’t you have to sterilize your jars and lids? Because you’re processing at a temperature high enough to sterilize everything inside the jar. Remember, pressure canning reaches temperatures of 240oF or higher and you’re processing for a long time. If anything survives in that, sterilizing your jar wouldn’t matter.
Let’s Get Started!
Always inspect the canner lid seal (if your canner has one) to ensure there are no cracks or tears. Make sure the vent pipe is not clogged. If using a dial gauge, verify it has been tested for accuracy by your county extension office, yearly. If not, just use your weighted gauge. The weighted gauge does not have to be tested.
First, you want to put about 2 inches of water in your canner (verify the amount in the manufacturer’s directions); make sure you have a rack in the bottom to prevent damage to your jars. Go ahead and turn on the heat to start getting the water hot. At this point, it doesn’t have to be boiling, but it will speed things up a bit if the water is hot when you put your jars in. Process your food and put it in the jars. If cold packing, use hot liquid to fill your jars. This will help prevent the “cold to hot” shock and minimize jar breakage. Run your de-bubble device around inside the jar to break free any air bubbles that may have been trapped. Then, verify the headspace as stated in your recipe (usually about 1 inch). Once you’ve done that, wipe off the rims of your jars to make sure there is no food or oils that could interfere with sealing. I usually use distilled vinegar but that’s not necessary; a clean, dry cloth works fine. It’s also a good idea to run your clean finger along the rim of the jar to make sure there are no defects that could also prevent the lids from sealing. Put your lids on, place the bands on and tighten finger-tight only. These are just to keep your lids from being displaced during processing.
During processing, pressure builds inside the jar. Remember, simple physics. As temperature rises in an enclosed space, the pressure also rises. Without the bands, the lids would not stay on the jars. If you tighten too much, the pressure building in the jar won’t be able to escape and will cause the lid to buckle. I usually tighten the lids without holding the jar until the jar starts to turn, then, holding the jar so it doesn’t move, I tighten slightly more. I have found this works best for me, but before long, you’ll find the way that works best for you.
Carefully lower the jars into the canner. Put the lid on according to your canner’s directions. Turn on the heat to medium-high. Do not put the weighted gauge on the vent pipe yet. Once you see a steady stream of steam escaping the vent pipe, start your timer for 10 minutes. This is to evacuate air inside the canner. According to the National Center for Home Food Preservation:
“Air trapped in a pressure canner lowers the temperature obtained for a given pressure (for example, 10- or 15-pounds pressure) and results in under processing. To be safe, USDA recommends that all pressure canners must be vented 10 minutes before they are pressurized.”
After 10 minutes, put the weighted gauge on the vent pipe. The proper amount of pressure should be reached within a few minutes. Start your processing time timer only after pressure is reached. If using the weighted gauge, listen for it to start “jiggling”. One type of weighted gauge should jiggle a certain number of times per minute, while another type should rock slowly throughout the process – check the manufacturer’s directions to find out about your specific canner. If using a dial gauge, start your processing time once it is reading the proper pressure for your altitude. If needed, you can adjust the temperature under your canner. My stove is set in increments of numbers. I usually start mine at 8 (medium-high) until I put the weighted gauge on, then slowly decrease in 0.5 increments over about 10 minutes. Usually by the time I reach 4, the weight has started rocking and I don’t go any lower. You will determine how high or low you need to have the temperature on your stove. It may be trial and error for a few times. Just remember, if at any time, the pressure drops below the recommended amount, you bring your canner back up to pressure and start your time over. Don’t decrease the temperature too fast or it may cause liquid loss from your jars. Some people call that syphoning. Not sure if that’s the correct term, but you may hear it.
After your processing time has ended, turn off the heat and let the pressure naturally decrease. Do not remove the weighted gauge or try to open your canner. Just leave it on the stove or burner until it has de-pressurized. Because my canner does not have a dial gauge, it has an air/vent cover lock that is up when the canner is pressurized, and it falls when the canner is de-pressurized. Once your canner has de-pressurized, you can remove your weight, and open the lid. The inside still has a lot of steam so, always remove the lid so the escaping steam is directed away from you. I also always wear oven mits to prevent steam burning my hands. Let the jars remain in the canner for another 5 to 10 minutes. Then, carefully remove them using your jar lifter and place them on the counter to cool. It’s best to leave 1-2 inches between the jars so they have good air movement for cooling. You may start to hear the jars “ping” even before removing them from the canner.
One thing to remember, everything inside the jar is boiling hot. You will continue to see bubbles inside the jar for quite a while – almost like it’s still boiling. Nothing is wrong. I was on a Facebook page for canning and new canners would often mention they saw bubbles in their jars, so they threw away all their hard work thinking they had done something wrong. It’s supposed to do that!!! Rejoice and be happy! Once you have all your jars out of the canner and cooling, leave them alone for about 24 hours. Don’t remove the rings, don’t check the lids, just leave them alone. If you mess with them, you can cause them not to seal.
So, how do they seal? Remember physics? As temperature inside a closed space increases, so does the pressure. The opposite is also true, as temperature decreases inside a closed space, so does the pressure. As the jars start to cool, the pressure decreases and basically forms a vacuum inside the jar. Give it time to work its magic. Once it has done its thing, that seal will remain in place until it is broken. That’s why, after 24 hours, you can remove the rings, wash your jars, and store them. Also, by removing the rings, you know your jars are sealed. If that seal is in place, your food should be good. Having said that… food that has been canned could still be good for more than a year, but it will start to degrade over time. It’s best consumed within a year. So, always write what is in the jar and the date processed on the lid.
A few things to remember, once a jar is sealed there aren’t too many things that can break that seal. In fact, I must use a can opener to get the lids off my jars. The most important thing to think about, though, is spoilage. Foods that spoil will build up gas within the jar and the seal could (most likely) break. If you keep your rings on your jars after processing, you won’t see that. I also check my jars every few weeks just to make sure they’re still sealed. I have found 1 on the shelf this year that lost its seal. Needless to say, that jar was dumped. Also, when you’re checking the seals after the 24 hours, if you have a jar that didn’t seal after processing, go ahead and use it, or put it in the refrigerator for a few days until you can use it. It will be fine. Or, if you choose, you can reprocess it.
I think that’s the basics of canning. Just remember, no matter what people tell you, be safe. Many people will insist you can water bath can low acid foods because that’s the way their grandmother and mother have always done it. They’ve been lucky that no one has gotten sick. Don’t take a chance. Follow the tested and proven way and you should be fine.
As always… Live life and have fun!