I will give my personal opinion. I might be wrong. It is your responsibility to decide for youself.

I think it is a mistake to raise the temp of tomatoes. it causes the tomatoes to change flavors. it tends to burn or darken the juice.

The best tomatoes and juice are when you keep the temp low.

I have a big 941 pressure cooker. It holds 19 quart jars. What I do is process for a longer time but I go just to the minimum pressure like 1 pound.

It may be tricky to understand but when you raise the temp up high by raising the pressure then you allow it to cool down. What I believe happens is that the pot cools first but the inside of the jar is still hot. Therefore the hot jar boils over in the low pressure cool pot.

To avoid this you must lower the temp extremely slowly. It is much better to never raise the pressure/temperature and you will not have so much boiling over. Although it can still happen at the lower temps so be careful and go down in temp slowly. But this problem is much worse if the pressure drops from 15 pounds to 0 pounds.

at zero pressure the temp of the boiling water is 212 F.

at 15 pounds pressure the temp of the boiling water is 250 F

much hotter and a slow decrease down of 40 F takes time to avoid boiling over. Imagine that the tomato juice wants to boil at 212 F and you have it up at 250. Way above boiling. You have a long way down to get below boiling. the only thing keeping it from boiling over is the pressure. And once the pressure does down the juice in the jar is going to boil because it is hot.

That sounds like a really dangerous practice, only canning at 1 lb. pressure ?? There is no way botulism would be destroyed like that. It is never safe to add time, processing longer at a lower pressure.
Gardnpondr,
You must have either filled the jars too full so they siphoned out or you raised/or lowered the heat too quickly at some point. That or see my note below about letting them sit another 10 min. once the pressure is gone in the canner.
Pressure canning is the best way to process tomatoes in my opinion. We teach both methods, but pressure canning is now the preferred method.
As long as your tomatoes are sealed and you used the right procedure for they type of packed tomatoes you did, they are safe. How long and what pressure did you use? What kind of canner, a dial or a weighted gauge canner ? Did you raw pack, hot pack, use water in the jars, etc ?
You don't remove the weight and lid after the pressure is down. You remove the weight, not the lid, and set the timer for another 10 min. That could also have caused the problem with the siphoning of the jars. You need to let them sit and depressurize before opening the lid that extra 10 min.

The best tomatoes and juice are when you keep the temp low.

That MAY be the case, gardendawgie but after many years of canning tomatoes I don't find it to be true. No change in flavor, no burning and certainly no darkening.

However I can say without any qualification that that is a very hazardous approach to canning tomatoes! Very risky! Unless consumed almost immediately the tomatoes would be potentially unsafe for eating. And any long term storage would be out of the question.

gardnpondr - Linda Lou's advise is right on and it is vital to follow the detailed cool down procedures. She teaches this stuff for a living. ;)

Siphoning has several potential causes, all discussed in detail on NCHFP, and pressure fluctuations during processing is the primary one. But it does happen now and then and while not ideal, the food is still safe assuming good seals form on the jars.

For me, whenever it happened, it was always caused by me changing the heat levels too much or too quickly. When that happens the pressure falls off just a smidge and liquid gets sucked out of the jars.

With practice and experience you learn to hit the perfect heat balance - do some practice with jars with colored water in them until you get a good feel for it and no colored water at the end. ;)

Dave

Here is a link that might be useful: NCHFP - Siphoning

Simply adding a little citric acid to the jars of tomatoes will help to prevent any health risk. A pressure canning is not necessary once the acid level is raised. Boiling Water Bath is the most current method used today for high acid foods. Use the pressure canner for low acid foods.

Citric acid sure won't compensate for proper processing. You MUST process for the safe time and method to destroy spoilage bacteria and get a true vacuum seal.
Trying to tell people to not do things safely is wrong.
No, pressure canning is not necessary, but it does result in a superior and more nutrious tomato product. Also, saves time for me. A boiling water bath for tomatoes packed in the jars, even with the required citric acid or bottled lemon juice is 90 min.
Since I deal with many people about canning, I do find pressure canning tomatoes seems to be the preferred and most widely done method.
This is from USDA :
Recommendation: Use of a pressure canner will result in higher quality and more nutritious canned tomato products.

There is no mention of the acid requirement Ken, just the processing methods. Linda Lou is right that just adding the acid or bottled lemon juice - which is required for both processing methods - doesn't make improperly processed foods safe.

We either do the full BWB with the added acid OR we can pressure can with the added acid. But either way, we need to do it correctly and the method described by gardendawgie simply isn't acceptable acid or no added acid.

Dave

I am NOT saying not to process, I am ONLY saying that citric acid is necessary to safely can the tomatoes IN ANY PROCESSING. A pressure canner is not necessary, as tomatoes and tomato sauces can be BWB with no safety isues, provided the person canning has some idea of what a BWB is and how long to have the jars in it. I've been BWB canning tomatoes for over 30 years and always add citric acid and always use a BWB canner. I still have a few jars left of tomato sauces that are still bright red color and are dated 1992 and older.

Oh my goodness, didn't mean to stir up a hornets nest!
I have a Presto Pressure canner with weight. I was following the Ball blue book on the time to process, can't remember right now how long it was. This is a new book, not an old one. I did follow the cool down in the book. That's WHY (because they were still in the canner and the water looked discolored. I thought the water was discolored but it wasn't. It wasn't the water IN the jars but the water OUTSIDE of them. Actually I didn't add water to the jars. It was only tomatoes and tomato juice in them. I used lemon juice like the book said as well as the salt. After I took them out, it was fine. I had left the jars in there like it said to do in the water. I do remember that I used 10 pounds pressure. Also they were raw when I put them in the jars. I didn't follow the directions in my canner book because I knew from reading on here the time they gave wasn't long enough. This is an older canner and seems times have changed since this canner was bought.
Thank you for all your responses!

ALSO while we're on this subject, I'm curious about something. A friend of mine pressure canned some potatoes the other day. When she took them out, one of the lids, not the ring, but the lid was bent up on the edge a little. WHAT would cause that to happen?

The lid buckled most likely from the ring being put on too tightly. There was no way for it to expand to allow it to properly vent.
Either that or they tried to hurry the cool down time and removed pressure manually, which is a bit "no no". The time it takes for pressure to build and the cool down time is part of the safe processing time.

No hornet's nest. ;) It is just the limitations of this medium. It is easy to misunderstand what a another poster "meant" to say. And none of us are ever as clear in our posts as we think we are. So we debate things like this all the time here but we always come to agreement in the end.

I understood what you meant about it being the water outside the jars - that is siphoning as mentioned above. It is nigh on to impossible for fluid to get inside the jars. Long as you follow a recent edition of the BBB you'll be fine.

Dave

I used to *finger tighten* the rings per canning jar instructions. Frequently I would end up with tomato juice in the pressure canner. Now I *hand tighten* the rings and rarely end up with siphoning.

Zeuspaul