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krypto2000
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Registered: 12/05/06
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Can anyone explain to me the logic in determining the amount of water in PC to Jars?
#18899478 - 09/27/13 04:38 PM (10 years, 4 months ago) |
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I don't have my manual yet everything says to refer to the manual or 'a few inches of water' and I can't think of anything to search for. What I'm wondering is the reason for this, there must be a simple formula to apply to all goods, be it grains for mushrooms or simply food canning.
What I'm trying to figure out is if you are only cooking a single grain jar vs 3, 7, whatever, does it matter how much water you surround it with and if so why? Do you always put it 1/3rd the way up, half the way up, "2-3" inches? In doing more or less does it change the cooking time? I know the point is to create steam and thus create pressure, but does the boiling water layer itself serve a purpose of any kind other than as a source for the steam? Does the layer have any effect on equalizing the pressure and/or water content between the inside of each jar and the PC water itself?
edit: One more question, is there any water exchange between the inside of the PC and the jars? I feel like there must be an equalizing effect. First I would think the moisture content of the jars would be equalized with the water content outside of the jars though it's probably a one way system as water cannot enter the jars but it can leave them. In other words at least after a certain level of water outside the jars wouldn't it have a buffering effect to the moisture content of the inside of the jars?
Edited by krypto2000 (09/27/13 04:48 PM)
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JamesSpawned
Fart smeller! Wait...



Registered: 01/15/13
Posts: 773
Loc: Treasure Coast
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Re: Can anyone explain to me the logic in determining the amount of water in PC to Jars? [Re: krypto2000]
#18899507 - 09/27/13 04:44 PM (10 years, 4 months ago) |
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I try to use the least amount of water possible. This gets the PC up to pressure the fastest and also uses less electricity.
-------------------- ARE YOU NOT ENTERTAINED?!
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myplague240


Registered: 03/17/13
Posts: 127
Last seen: 10 years, 3 months
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Re: Can anyone explain to me the logic in determining the amount of water in PC to Jars? [Re: JamesSpawned]
#18899574 - 09/27/13 04:59 PM (10 years, 4 months ago) |
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A 3" level of water is completely sufficient. The reason it varies and people say to fill pressure cooker "X" amount up the jars is just to ensure you have enough water and the pressure cooker doesn't boil dry. It's not really a big issue, if you use 3" of water or so the water isn't going to dry up. Even at 90 minutes of 15 psi you will still have extra water left. Cooking under pressure requires less liquid than conventional cooking methods since there is less evaporation. You can always use more liquid than recommended in a pressure cooker but never use less. The whole concept of a pressure cookers is simple. Water or any cooking liquid comes to a boil at 212 degrees F. Once it does it produces steam. Steam is hotter than boiling water and can reach approximately 250 degrees F. Trapped, hot steam builds and builds putting the desires PSI on your jars, instruments, etc. Things should sterilize OK if you live at sea level to 2000 feet above sea level. After that, a good rule of thumb is to increase the cooking time by 5% for every 1000 feet higher than that 2000 foot base.
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krypto2000
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Re: Can anyone explain to me the logic in determining the amount of water in PC to Jars? [Re: myplague240]
#18900040 - 09/27/13 06:57 PM (10 years, 4 months ago) |
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So basically as long as there is enough water it's safe, even if there is less than is recommended? "Enough" meaning all of the water doesn't evaporate which can be observered as steam coming out of the rocker/release valve and of course there being some in the bottom of the PCer after cooking?
I Could see the food getting burnt if the water level drops below the tray or towel or whatever you have in the bottom of your PCer, but even then it should be ok since as long as there is steam the tray/towel/whatever shouldn't rise above the temperature of the steam. Do you think there would be any benefit to using less than recommended so long as enough since then it would cook faster?
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cubenpete
Aminita good excuse



Registered: 03/13/12
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Loc: Kentucky
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Re: Can anyone explain to me the logic in determining the amount of water in PC to Jars? [Re: krypto2000]
#18900139 - 09/27/13 07:18 PM (10 years, 4 months ago) |
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I keep my water level at about 2" or less up the jars. This is because many of my jars use a polyfill filter for GE, and I don't want them to get wet/ruined by bubbling water compromising the foil cover from where the foil and glass meet (really don't know if I just paranoid but until they make a transparent PC gonna stick with it) . If you are using SFDs, which are waterproof you don't have to worry. I always have a lot of water left after a 90min session, even when I let the weight gently rock the whole time.
Less water = faster cook
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bodhisatta 
Smurf real estate agent



Registered: 04/30/13
Posts: 61,890
Loc: Milky way
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Re: Can anyone explain to me the logic in determining the amount of water in PC to Jars? [Re: cubenpete]
#18900232 - 09/27/13 07:35 PM (10 years, 4 months ago) |
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Quote:
The whole concept of a pressure cookers is simple. Water or any cooking liquid comes to a boil at 212 degrees F. Once it does it produces steam. Steam is hotter than boiling water and can reach approximately 250 degrees F. Trapped, hot steam builds and builds putting the desires PSI on your jars, instruments, etc
No
How does steam get hotter than boiling water if it can't obtain more energy? The water boils and the steam has no where to go because of the weight. This increases the PSI and in simple terms makes it harder for the water to boil (dealing with vapor pressures). The hotter the burner the faster the water will boil but it will only reach 212 under atmospheric pressure. The pressure makes it so the water can absorb more energy reaching 250F to compete with the pressure to make the steam and reach equilibrium. The water is also at 250F when the PC reaches 15psi as well as the steam.
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