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Safe to keep empty jars hot in the oven before filling?

Posted by valereee 6a SW Ohio (My Page) on
Sat, Aug 30, 08 at 6:47

I searched on this and found a couple of threads that touched on it, but it seemed as if there was varying advice. I want to PC ~20 pints of spaghetti sauce. In order to do this, I need to do two layers (I have a second rack to place atop the first layer), which means I can't keep the empties in the hot water inside the canner and replace them with full jars as I go. My stove doesn't have enough room for another large pot of hot water. I've read that some folks put their jars into a hot oven (some say they put just the jars into the hot oven, some put them into a pan of hot water in the oven), but I've seen others say that's not recommended.

What's the current advice?

Follow-Up Postings:

RE: Safe to keep empty jars hot in the oven before filling?

I think keeping them hot in the oven is fine but using the oven to "sterilize" them is not. Here's a thread about ways people keep their jars warm.

Here is a link that might be useful: Keeping jars hot

RE: Safe to keep empty jars hot in the oven before filling?

mom2, yeah, I read that thread. There doesn't seem to be any consensus, and on another thread someone said keeping jars in the oven wasn't recommended, although possibly what they meant was that it wasn't recommended to use the oven to =sterilize= the jars. I wasn't sure.

RE: Safe to keep empty jars hot in the oven before filling?

Hi Val,

The jars do not have to be super hot - I simply fill mine with hot tap water just before filling and line them up on the kitchen counter. To fill, I pour out the water into the sink, give the jar a couple of shakes, and fill immediately with the hot food. Never had a jar crack in over 30 years.

I'm sure an oven would be equally good, just don't make them too hot to handle.


RE: Safe to keep empty jars hot in the oven before filling?

valeree, I use my oven to keep jars hot. I'm a pretty slow worker and even for a single batch (a dozen 8-oz jars, say), the last ones could be quite cold by the time I was ready for them otherwise. (For small jars I use the toaster oven.)

If I am doing just a few and the last ones seem to be cooling a bit too much, I sometimes do like Tom and re-warm them with very hot tap water.

I admit I haven't seen any official recommendation on this, but the sources all seem to say the jars should stay "hot," and it seems to me if it were important they be boiling-level hot right up till the moment they were filled it would say so!


RE: Safe to keep empty jars hot in the oven before filling?

If you are concerned about breakage I wouldn't worry too much. I always pour my boiling hot tomato sauce into room temperature canning jars. I have never had a jar crack.


RE: Safe to keep empty jars hot in the oven before filling?

I do as Zeuspaul does, except for jams and jellies. I keep those jars in boiling water until ready to fill. I store my ready to use jars in my dishwasher.

RE: Safe to keep empty jars hot in the oven before filling?

I don't heat my jars. After they have been sterilized I just put them on the counter lined up to be filled. If you touch a jar after you have filled it up with boiling hot veggies or jelly or whatever, you realize it immediately becomes very hot from what you put into it. IMO I think it is a waste of time and energy to heat them up and keep them warm.

I think this notion came about when people were canning in cold houses and kitchens way back when. There the difference between ambient air temperature making the jars cold and filling with hot product might make them shatter. I know that the modern canning jars are made to allow both heating and freezing, thus are tempered glass, to resist shattering. I've never had a jar break while filling it. Even when cold packing, I see even less a reason to heat the jar as long as it has been sterilized.


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