Topics regarding canning meat
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Hi all. I've been researching canning, and have done a bit with vegetables in the past, but I still have one nagging question. I see occasional references to using a pressure canner, vs using a pressure cooker for some types of canning. I'm getting a lot of contradictory information here, and am trying to sort it out. When is it recommended to use the pressure canner instead of a pressure cooker? There's a huge cost difference, and the little bit of canning I do has been perfectly acceptable with the pressure cooker.
I don't know if this directly answers your question but here it goes.
My pressure cooker has only a weight on it to increase internal pressure for faster cooking in a short period of time.
My pressure canner has a weight and a gauge to monitor the pressure and heat for long periods of time.
In other words a standard pressure cooker's internal temp and pressure can't be monitored to insure long term storage where a canner has the gauge to insure you maintain the heat and pressure to properly preserve food for long term storage.
A foot note. I recently learned that a majority of pressure cookers ship with a 10 pound weight. If you are at altitude the is 5 pounds too low for proper canning.
They are essentially the same thing. Caners are generally larger and give you the option of pressure settings, although some cookers have that option and some caners don't. If I planned to do any canning I would choose the size I need with adjustable pressure settings. You don't want to run out of water and should be following directions, including pressure setting. Swamp
Cookers tend towards having a jiggle weight which is not very regulated in regards to pressure. Canners have either a pressure dial or a jiggle weight with a pre-regulated pressure attached.
Cookers don't allow for fine tuning and long term cooking.
Canners do allow for fine tuning and long term cooking. They're also larger and fit 7-20 quarts of food, depending on model.
According to USDA, a canner must be able to hold at least 4 quart jars, and have a gauge or weight to allow you to measure 5, 10, and 15 lbs. pressure. However, any pressure CANNER can also be used as a pressure COOKER, it is just a matter of whether or not you want to use such a huge pot to pressure cook something. My Presto Pressure Canner says right on the box “Pressure Cooker / Canner”.
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Interesting. My old Mirro is weighted for 5, 10, & 15 lbs. I bought it long, long ago, and don't have the original box anymore to doublecheck it's true identity.
ETA: Mirro rate it as a canner, it will hold 4 quart jars, and does have the multiple weights, as mentioned before. Mine is pretty little though, being rated at 8 quarts capacity. It still kind of looks like a tossup.
RH, Mirro "8 quart" is a true combination pressure canner/cooker.
I have one and have canned it it several times.
It's for virtually the same as the 6 quart my Gma has only a bit taller but somehow that 6 quart isn;t safe to can in.
The smaller the cooker/canner the quicker it heats up and the quicker it cools down. Safe canning times have been determined in larger canner with more mass. Larger canners hold onto the heat longer and keep the canned jars at the elevated temperatures longer. These variables were taken into consideration when calculating and testing safe canning times. Those variables are very different in smaller cookers and thus the times for safe canning are unknown.
That sounds good until you think aboot it.
An 8 quart with 7 pint jars in it will cool down faster then a 6 quart with 7 pint jars in it. The difference in heat up time is nil.
Safe temps should have been reached long before you shut the burner off anyway.
The weight and thickness of the canners vary as does the volume of water in the canner. The larger canners are heavier and hold more water and thus have more mass and maintain heat longer and as well as taking longer to heat up. This gives the food more exposure to optimum temperatures for longer periods of time. The times are not set at just getting the food to 240F but also for x amount of time of exposure at 240F and then you cool it. Part of the time at 240F is when you start the cool down time. As it slowly cools it is still remains at or above the 240 for the certain amount time which is factored into the times set out be the USDA. Small /cookers/canners get to pressure quicker and thus the resulting food in jars are still in the process of being heated up and are at a lower temperature when the canner hit desired pressure of 10psi. Then the time is started and when done the canner cools quicker. The food doesn't get to the desired temperatures and stay there long enough for desired effect of denaturing all the spores sufficiently to prevent growth when it gets back down to optimum temperatures for the bacteria to grow. The difference between the two canners in your example may be small but could be enough to cause one to fall below the line of safety if the one is right at the bottom of the safety margin. Currently even the USDA's 4 quart jar recommendation is being re-evaluated as to whether that allows adequate heating at 240F for enough time. It may possible to can safely in smaller cookers they don't have any data with which to give times that will ensure a safe canned product.
The 6 and 8 quart mirro are the same gauge and use the same amount of water.
No it doesn't. It's only at 240 when it giggles and that is when you start the time.
That's an oxmoron. If it has cooled, it isn't at 240 anymore.
Do you really think they are splitting hairs that closely?
You are talking about the smallest sized acceptable (even that is being re-evaluted) Therefore anything smaller than the smallest acceptable will by definition be too small to use. (8 quart to 6 quart is a 25% reduction in size) The weight jiggles at 10psi allowing the temps to get to 240F and the food though requires time to reach 240F, When the heat is removed there is a lag due to the mass of the pot, jarred food and water before the temperature of the food starts to drop. The smaller the canner (water volume, metal thickness and amount of food) the quicker the heat loss the quicker the temperatures drop. The safe canning times were set and determined safe for the larger canners and don't not apply for smaller canners. These variables differ greatly between a large canner and small cooker. While currently being debated (they think it should be larger) the smallest size they feel can be used safely with current pressures and times is canners/cookers that will hold a minimum of 4 quart jars. You can go through the canning motion with smaller cookers using pint and 1/2 pint jars and end up with sealed jars but the times needed for safe canning will be different than that of larger canners.
According to who?
Your talking 30 second or a minute or so here.
Certainly you are not depending on that extra minute to get your food to temp?
What part of the canner being the same thickness and the water volume and jar contents being equal don't you understand though?
There is no magic in the extra 2" in height between the two canners I am talking about.
I don't have a large pressure canner, but if you wanted to cook a smaller meal in one, can't you just put a metal or glass bowl inside to hold the food when you don't want to pressure-cook a lot of food at once?
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During our Canning coaches certification we had a discussion about the smallest size canner you can safely use. The current consensuses is that the smallest canner was one that could hold a minimum of 4 quarts since they would have sufficient mass to allow for similar heating and cooling curves to that of the larger canners. It was pointed out that some are testing the 4 quart minimum as they feel it's not big enough for safe canning due to the physics and temperature properties discussed earlier. Your decision to follow the guideline or not.
15 posts • Page 1 of 1
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