Pressure Canning - leave jars in canner overnight after processing?

[jgcrawfo]

Hi,

I have a question about pressure Canning. I'm running my first batch of stew right now, and had a question about the end of the process. I might want to go to bed before the pressure drops down to ambient, so I was wondering if there was any reason I couldn't, or shouldn't, just leave the jars in the canner overnight?
That way the canner and the cans will both come down to temp together and I can go to sleep as soon as I turn the heat off.

Thanks for any advice!

 

[taxlady]

I have no idea, but hi and welcome to Discuss Cooking. Waving from near Montreal.

 

[Josie1945]

Hi JG,
I do a lot of canning and you will be fine
turning off the burner and leaving the jars
in the pressure canner.
Welcome to DC

Josie

 

[Bama-Rick]

It's fine to leave the jars in the canner to cool overnight. The only problem you may have is if one of the jars didn't seal. When you take them out of the canner you can usually tell if the jar has sealed within 15 to 30 minutes and if one doesn't seal I put it in the fridge and eat it within a day or two.

By letting them cool in the canner you are leaving an unsealed jar at room temperature for hours which could be risky however, they are enclosed in a sterile environment so the risk of food born illness using your method is almost nil, but that is the only issue I can think of.

 

[Chief Longwind Of The North]

If the jar dosen't seal properly while in the water., there will be water drawn into the jar
This may ruin your canned stew. Place the pressure canner into your sink and run cold water over the lid.n canner will be safe to open in a minute or two. Then you can remove the jars
They will seal and you will hear the lids pop between 10 and thirty minutes. The lids will depress in the center. When they are sealed, screw the lids on more tightly and place on your shelves. Just make sure all pressure
is released from the from the PC before removing the lid.

Seeeeya; Chief Longwind of the North

 

[Farmer Jon]

Sometimes I leave them in the canner but I unlock the lid and cock it to the side a little to let the heat out. Within a few minutes you will hear all the lids ping.

 

[Bama-Rick]

Won't running water on the canner to cool it down quickly risk causing the liquid to be boiled out of the jars? Quick pressure differential...

 

[jennyema]

Wont it overcook?

 

[Farmer Jon]

It's not safe to just shut the stove off and walk away.

Do not run hot water over your canner with jars in it. That's a good way to break them. Let it cool naturally. Then remove the jars and cover with a towel or leave them in the canner but cock the lid to let the heat vent out.

 

[bethzaring]

It's not safe to just shut the stove off and walk away.

Why isn't it safe?

I have done it many times over the last 45 years I have been pressure canning.

No, the food will not overcook if left in the canner overnight.

It is not recommended to cool the canner under running water in order to release the pressure early. It is recommended to let the canner cool naturally, overnight if that is convenient for you.

 

[GotGarlic]

It is not recommended to cool the canner under running water in order to release the pressure early. It is recommended to let the canner cool naturally, overnight if that is convenient for you.

This seems like one of those things that people used to do, but it's not recommended anymore.

I can't imagine carrying a pressurized pressure cooker, full of water and jars, to the sink anyway. Not a good idea.

 

[Farmer Jon]

Why isn't it safe?



I have done it many times over the last 45 years I have been pressure canning.



No, the food will not overcook if left in the canner overnight.



It is not recommended to cool the canner under running water in order to release the pressure early. It is recommended to let the canner cool naturally, overnight if that is convenient for you.

Ok I had to do a little digging to find the answer because I couldn't remember the name of the bacteria. In doing that I found it is infact safe but may not be recommend.

*Cooling too slowly after removing from canner. (Example: stacked jars close together.)

There is a group of harmless organisms called
thermophiles that can survive canning. If bottles are held hot for long periods, they can produce acid (fermentation). This results in the defect known as “flat sour.” This is harmless, but produces an undesirable flavor.

 

[jennyema]

Why isn't it safe?


No, the food will not overcook if left in the canner overnight.
.

Why wont it overcook if just left to cool on its own?

 

[bethzaring]

Why wont it overcook if just left to cool on its own?

Because once you turn the heat off, the heat/temperature/pressure immediately starts to drop. By 20 minutes, the pressure is gone. There is no more cooking while the jars sit there for hours.

Think what the jars of food have just gone through. For me, it's 75 minutes at 14 pounds of pressure. The food does not cook more during the cooling process.

 

[GotGarlic]

Because once you turn the heat off, the heat/temperature/pressure immediately starts to drop. By 20 minutes, the pressure is gone. There is no more cooking while the jars sit there for hours.

Think what the jars of food have just gone through. For me, it's 75 minutes at 14 pounds of pressure. The food does not cook more during the cooling process.

The pressure is gone, but the water and the food are still very hot, and they stay hot for quite a while. That residual heat continues to cook the food. It's just not at the same temperature as it is under pressure.

I've never pressure-cooked anything, so I have no experience. I imagine the food is quite soft, though. Vegetables are not likely to have much, if any, crispness.

 

[bethzaring]

The pressure is gone, but the water and the food are still very hot, and they stay hot for quite a while. That residual heat continues to cook the food. It's just not at the same temperature as it is under pressure.

I've never pressure-cooked anything, so I have no experience. I imagine the food is quite soft, though. Vegetables are not likely to have much, if any, crispness.

The jars of food are quite hot whether they are in the canner or outside the canner. You would need a source of heat for the food to overcook. There is no source of heat. The jars are cooling in an aluminum pot. Aluminum does not hold heat. What am I missing here?

Do you think canned green beans area crisp? Canned foods will never be crisp.

 

[bethzaring]

maybe this will help you understand...

USDA process times rely on a combination of heat from the time the canner is coming to pressure, during the actual process time, and then during the early stages of cooling the canner and jars. Even after the heat is turned off under the canner, at the end of the recommended process time, the food remains at high enough temperatures for another period of time that can still contribute to killing of bacteria. This retained heat while the canner has to cool naturally to 0 pounds pressure before opening is used to advantage in calculating the total sterilizing value of the process to preserve some food quality…. if anything is done to shorten the cooling period, including using a very small cooker or force-cooling the canner, then the food could cool down more quickly than expected, and be under-processed….Bacteria are not killed in the food only during the process time; the time it takes the canner to come up to pressure, the process time, and the cool-down time all matter.” [2]

 

[Bama-Rick]

Allowing the canner to cool over night won't hurt anything. You have boiled the food at 240-250 degrees for an hour and a half so it's cooked to softness anyhow and the temperature starts to drop as soon as you take it off the heat.

There are a few advantages to letting the canner cool over night. The big advantage is safety. When you remove the jars as soon after the pressure drops to zero the jars and the food inside the jars is still 212 degrees. If you drop one of those jar you're going to end up with first or second degree burns wherever the hot food splashs on to your body.

Also while I've never dropped a jar when gripping them with canning tongs, the grip on the super hot jar always seem precarious at best. If the jars cooled overnight you can simply reach into the canner and remove them by hand.

Yesterday, I canned some turkey soup, when I opened the canner some of the hot water clinging to the lid dripped down onto my leg, it caused a first degree burn. Leaving the canner to cool overnight eliminates that hazard.

 

[GotGarlic]

The jars of food are quite hot whether they are in the canner or outside the canner. You would need a source of heat for the food to overcook. There is no source of heat. The jars are cooling in an aluminum pot. Aluminum does not hold heat. What am I missing here?

Do you think canned green beans area crisp? Canned foods will never be crisp.

Jars sitting in hot water will stay hot longer than jars that are on the counter. The hot water the jars are sitting in is the heat source. I think that is the source of the idea that food in jars in hot water overnight might overcook.

No, I don't expect canned goods to be crisp, but holding them in hot water after the pressure cooking time has elapsed could cause them to become mushy, which is not appetizing. I would consider that overcooked.

 

[bethzaring]

Jars sitting in hot water will stay hot longer than jars that are on the counter. The hot water the jars are sitting in is the heat source. I think that is the source of the idea that food in jars in hot water overnight might overcook.

No, I don't expect canned goods to be crisp, but holding them in hot water after the pressure cooking time has elapsed could cause them to become mushy, which is not appetizing. I would consider that overcooked.

This is not a problem. There is maybe an inch of water in the canner, and the jars are on a spacer which keeps them off the bottom of the canner. Actually, the jars of food will be hotter than the little bit of water around the bottom of the jars. Are you folks thinking the jars are submerged in water, like in boiling water bath? A pressure canner starts out with three inches of water in the canner at the beginning of the process and loses much of that in the canning process.