That site has been discussed here and links have been posted previously, though not for a while.

However, one caveat is that this publication is ten years old, based upon 1988 USDA recommendations. I mention that only because many are now growing heirloom varieties and dense pulp varieties which may not have been considered in the original testing.

The document does recommend the addition of acid for those individuals who are using one of the varieties listed previously, who are using unknown varieties, or who wish to further minimize any potential botulism risk.

That statement covers a pretty large group, particularly the line who wish to further minimize any potential botulism risk.

However, it is a purely personal decision. No one is required to follow the recommendation, and that would be true even if this document did not exist.

Elizabeth Andress has been wonderful about responding to emails. I know earlier she had mentioned (when I asked about pressure-canning tomato paste) that they were working from data generated originally by the USDA, not new data. Unfortunately, some of that data was lost or never transmitted to the NCHFP. Without the raw numbers they can't extrapolate alternative processes.

Carol

Yep - discussed and debated here many times before. ;) It's your choice.

Note: The USDA methods given in this publication are based on research released in 1988, sponsored by the United States Department of Agriculture, and conducted at the Extension Service Center for Excellence in Home Food Preservation, Pennsylvania State University.

Those 1988 guidelines have since been revised by USDA - twice. So the U of M is basing their recommendations on what is outdated and subsequently revised research. They have been asked many times to update the info on their website or to at least add a disclaimer but apparently choose not to do so for some reason.

USDA's point is that it is not just the variety of the tomato that determines its pH, it is also the soil and growing conditions used. They can affect the pH substantially as can the pH of your water used. So the official position is that "knowing the variety of your tomato" isn't enough to insure proper pH OR to maintain the pH stability of the canned item over time.

Proper acidification during processing insures your safety. Refusing to do so is your choice, your risk to take. ;)

Dave

Oh - I see Carol beat me to it.

Dave

My question (to the NCHFP) was very simple.

According to the NCHFP:

Carrots, (with a pH of 4.9 to 5.2) can be safely pressure canned in quarts for 30 minutes at 15 psi (for my altitude)

Beets, (with a pH range from 4.9 to 5.6) can be safely pressure canned for 35 minutes at 15 psi (for quarts at my altitude)

So now, tomatoes, (with a pH range from 4.2 to 4.9) must also have a corresponding time and pressure for safe pressure canning - without any acid added. So what is this time and pressure?

The answer was that they don't know, because they only tested acidified tomatoes.

If they don't know, someone must know, so I kept searching for this information.

There are folks that are pretty upset about having purchased pressure canners primarily for tomatoes and then finding out that the NCHFP is still recommending adding acid to them. To some of us this defeats the whole point of a pressure canner (I have no desire to can either beets or carrots).

This is why I was happy to find a site where they reported tests on non acidified tomatoes both with BWB and pressure canners. I do not see why tests performed 10 or 20 years ago are not valid today, so I feel comfortable and safe with the U of Minnesota recommendations. I understand many of you will not though, and of course you should not use these recommendations if you are not comfortable with them. Since I was excited to find this information I thought I'd share. I had read threads on this topic here, and I know I am not the only one bothered by this adding acid to my precious heirloom tomatoes. Sorry if this was already posted here before.

I have not had much luck finding density information for different foods, but my experience indicates tomatoes are probably less dense than carrots and beets. So I guess pretending I have beets (instead of tomatoes) could be one approach, and probably overkill, since beets are both denser and lower in acid than tomatoes. One concern would be over-processing, but I do not mind cooking tomato sauce for a long time, sauce is sauce, mushiness is not a concern here. Not sure if I will do that, of simply follow U of M process (they let the canner reach the desired pressure and then turn it off).

One of the goals behind the testing done at the USDA labs is to end up with not only a safe product but an edible, desirable product. In other words, why have it be safe if it is inedible?

Sure you could likely pressure can un-acidified tomatoes for 30 or 35 mins like beets or carrots and they would be safe but the end result would be undesirable soupy mush. So the effective compromise they developed is to acidify them and then, depending on which method you use, you only have to PC them for 10 mins. or you can do them for a longer time but at only 5 lbs. of pressure. The end result is both safe and desirable.

Obviously we would all wish for greater testing and approved recipes for many things. No doubt about it. But in the real world on limited funding that just isn't possible. So the best USDA can do is provide basic tested guidelines that serves the majority and let you choose which way to go from there.

I'd regret someone going to the expense of buying a PC merely for tomatoes as it is so unnecessary. But the acidification requirements even when pressure canning has always been there since the PC guidelines for tomatoes was developed so if they just bought a PC just to avoid that requirement they were mis-informed.

As always, the choice is yours. We all make compromises of the guidelines now and then. Hopefully those compromises are based on a good understanding of the process involved. If not we may well pay the price. But where I and others here draw the line is at publicly advocating those compromises, those unapproved methods to others as safe.

And for those who find the taste of either the bottled lemon or lime juice unacceptable, there is always citric acid which imparts no flavor to the tomatoes. It is the same product used in all commercial tomato canning.

Dave

Tomatoes do not have the same density in a jar as carrots or green beans, etc. Density is also just as important as ph when canning. The heat penetrates the foods at different rates in the canner. The more dense the food, the longer the processing time. For example, a juice will take much less time that pieces of food in a jar. You cannot be insured the processing time for something with a comparable ph level will be sufficient, as the density will not be the same.
Also, most folks are not willing to pressure can tomatoes as long as they would take if not adding acid. They do it so it will also be more convenient for the majority of people. As was said, you would have mush, too, in the jars with the tomatoes.
Dave made a good point, even the commercial industry has to add citric acid to their tomatoes.
You also have to realize you may not live in Minnesota. That is only one state out of 50. As was said, you soil will yield tomatoes with an unknown and different ph than the ones they grew. Even my neighbor and I cannot be certain ours are the same ph level. The soil will make a difference.
Please, don't take a chance. Use the acid in your tomatoes.
I teach food preservation safety, so I get really concerned when I see people taking unnecessary risks with their foods.
Those Minnesota guidelines are outdated and risky to use. No one would tell you to bring a canner up to pressure and shut it off nowdays with the most current methods. We don't have people use 15 lb. pressure unless you have to due to living in higher elevations.
We are dealing with all kinds of budget cuts. Also, even in the food preservation field there are MANY who are thinking we should just go to online courses, no more hands on classes and labs. We are teaching our hearts out while we have the chance. Comes to no surprise that Elizabeth would say what she did. There is no money to fund these programs.

We are no longer funded to research new processes; perhaps you might want to share your request with companies like Jarden Home Brands (maker of Ball and Kerr jars), Mrs Wages or Presto who all supply the home canning industry."

It seems like the USDA NCHFP is now admitting they are passing the buck to others for the latest developments in home canning and that they are using dated information and are no longer researching new processes.

That is a refreshingly honest reply from the USDA. We used to get promises of new standards, and promises and promises. Now we are told there is no new research. Being told the truth is a good thing. I just don't see how they can be held in such high regard as THE standard for home canning. What they are is a repository for dated information.

Thanks cabrita for well composed and researched question. You hit the nail on the head. Many of us do not care if our tomatoes are mushy because we are making sauce! Acid is added to whole tomato products to reduce processing times and keep the tomatoes from becoming mushy.

I believe tomatoes are low acid foods and can be safely pressure canned just like other even lower acid foods. That's just my opinion, not a recommendation.

Our once great nation can't afford to research new home canning processes. Pretty sad.

Zeuspaul

"...Our once great nation can't afford to research new home canning processes. Pretty sad."

AMEN. They spend Billions on other things that have nothing to do with our self interest or self protection however.

Jim in So Calif

Cabrita

The USDA does have a pressure canning no added acid processing time for spaghetti sauce which is primarily tomatoes with garlic, onion, green pepper, mushrooms and some spice added. There is a specific Caution: Do not increase the proportion of onions, peppers, or mushrooms. These are low acid vegetables and it is often indicated that they can be reduced but not increased. If you reduce the low acid vegetables you are pretty much left with tomato sauce.
http://www.uga.edu/nchfp/how/can_03/spaghetti_sauce.html

Also there is a no added acid pressure canning recipe for stewed tomatoes tested for both pH and heat penetration reviewed and adapted for use in South Carolina by P.H. Schmutz, HGIC Food Safety Specialist, and E.H. Hoyle, Extension Food Safety Specialist, Clemson University. (New 06/99. Revised 08/07.) This recipe also contains peppers and onions so the same cautions apply.
http://www.clemson.edu/extension/hgic/food/food_safety/preservation/hgic3360.html

I believe everyone should follow USDA guidlines.

Zeuspaul

"Thanks cabrita for well composed and researched question. You hit the nail on the head. Many of us do not care if our tomatoes are mushy because we are making sauce! I believe tomatoes are low acid foods and can be safely pressure canned just like other even lower acid foods. That's just my opinion, not a recommendation."

I agree with Zeuspaul.

I pressure can my salsa (lots of onion & garlic) at 15 lbs for 25 minutes and it does not get mushy at all. I do add citric acid because I found that it has no detectable affect on the taste of my salsa.

TomNJ

Zeuspaul, thanks for bringing the spaghetti sauce recipe from that site. I had overlooked their recipes since I was looking for the very simple processing of tomato pulp after passing it trough a mill and just adding a little salt. We would then flavor/season it right before using, depending on what we use it for. However, making sauce is a good option, and also, as you say, I can simply substitute the low acid ingredients (peppers, onions, garlic) with just more tomatoes, omit the oil and voila! it is even safer and I do not mind using the processing times of 25-30 minutes. After all, I would cook a pasta sauce on the stove top for a long time anyways. Doing this we still follow USDA recommendations and adjust for a potential lower acid tomato by using the pressure cooker.

Thanks you Dave and Linda for your responses. After reading all your comments and going to the appropriate links I decided that I will follow the more stringent - Pressure cook for 25 or 30 minutes - rather than the U of M recommendation to just bring the pressure canner to pressure and turn it off. Processing for 25-30 minutes feels safer and will not hurt the product canned (sauce or soup). Also, as Zeuspaul points out, it is within the recommendations from the NCHFP! (it is just slightly hidden).

TomNJ thanks for the report on pressure cooking salsa, glad it does not get mushy even with the PC. Now vinegar or lime/lemon juice does not bother me at all on salsa (I use it even for fresh salsa) so we will probably try Annie's salsa just like it is, changing only the scoville rating of the peppers (not the amount of peppers). That would be BWB though. No problem there.

One type of tomato that gave us the most delicious pasta style sauce (and fresh gazpacho but I want to make hot soups too) was made with Kelloggs breakfast (large orange tomatoes). Unfortunately last year's were so sickly and weak it was not even worth saving seed so we are starting new orange tomatoes, to see what orange variety does well here. Persimmon is one we are trying this year (among others). Just from tasting these types of tomatoes my guess would be that they are the lower acid types. However, putting citric acid or lemon juice on them would not work for me. This is why I am so glad to have a pressure canning options just in case we get a good harvest of orange/yellows. Other orange/yellows we are trying are Golden Queen, Rainbow, Nebraska wedding and Azoyka (sp?).

There are also two tomato soup recipes that do not require acid/lemon juice added and that I plan to try (both). I will bump that thread or copy/paste since this site seems to be loosing valuable old threads.

We have raised Persimmon with excellent results, but only in "good" years with lots of sunshine. It's just a toss-up how the weather turns out. But we found it a wonderful tomato in the years when we're lucky enough to have favorable growing conditions, healthy, vigorous and with a wonderful flavor.

Remember taste is no indicator of acidity as it's just as likely the tomato tastes less "acid" because it's higher in sugar. That's certainly true of a number of yellow tomato varieties. (Taxi comes to mind.)

Carol

cabrita,

I've enjoyed reading your thoughts and research on this thread --- thanks!

I second Carol's comments on tomato acidity --- some knowledgeable tomato forum folks have shared research showing that, while most people find a lot of yellow tomatoes taste less "acidic" than most reds, they don't actually tend to be lower in acid, but higher in sugar. Most of the ones that are low acid are varieties that were specially bred for that purpose mid-century, like Jet Star, but there are a few others that have tested below the threshold; ripeness can also be a factor. (And I imagine the weather, as it can affect water content. But that's just my musing.)

I LOVE yellow tomatoes. Thought I've noticed a lot of those with yellow or gold in their names are really orange. (And those with purple in their names are pink; those with black in their names are usually purple --- go figure!)

I have done very well with Amish Yellow, which also has the advantage of being pretty meaty (for a thicker sauce faster!). Same with Yellow Bell. I also love Yellow Perfection, which produces millions upon zillions of tasty little yellow golf balls --- not so handy if you make your sauce by peeling (since it takes a long time to do small ones) but no problem if you use a food mill.

An orange that did really well for me last year was Earl of Edgecombe. I tried it several years in containers with measly results but once in the ground it seemed happy.

Kellogg's Breakfast I've really enjoyed too but it is a late and not very productive variety for me so I couldn't count on it for batches of sauce....

(Of course, your climate is v. different; do you have a v. long season or is it too hot for some of the year where you live?)

Usually I mix tomato varieties for sauce but every year I try to make a batch or two of all-yellow and/or all-orange sauce and the colourful jars just make me smile all winter, and do tend to have a distinctive taste with a bit of citrus zing.

Good luck!

Zabby

Carol and Zabby, thanks for the feedback on the orange varieties! Now I have more of them to try for next year. Very interesting about the acidity. It makes sense, our oranges/tangerines seem to loose acidity later in the season, but in reality they just get more sugar, so the acidity is not noticed as much. Seems like the same story with the orange tomatoes.

I have been feeling stupid and kicking myself in the butt for three years, my first encounter with a Kelloggs breakfast that was so productive we made sauce with them, and I did not save seed! I thought that was 'normal'. Silly me.

Carol, my seed source for the persimmon (an old friend) is in Portland Oregon, small world? Taxi is such a cool name for a yellow tomato.

I forgot we are also trying rainbow (orange and red bicolor) and of course, again sungold cherries, but those are not for canning. I agree Zabby that the bicolored ones probably make the most awesome looking jars of tomato chunks and sauce.

Extreme heat here happens more during the fall (every other year it seems). This is after the tomatoes should be done fruiting, once the fruit is set, extreme heat is less damaging. Possibly an 'issue' we have is extreme thermal variations between day and night, and heat spikes so we could be 50 degrees F cooler from one night to another day at noon on the same week for example. I think some tomatoes do not like that, and we are testing many varieties to see which ones tolerate these fluctuations.

cabrita, last year after making the USDA/NCHFP approved recipe 'Tomatoes with (Okra or) Zucchini' I was frustrated by the same question you have. The approved recipes I found said I could can tomatoes and zucchini together with no added acid, but plain tomatoes were not safe unless acid was added. It made no sense. Dropping the zucchini could obviously only improve the acid status - if I remember zucchini is 95% water. And considering the sometimes thick texture of its green peel, change in density would not appear to be a problem. Since I prefer tomatoes NOT be intact when cooking into sauce, I did all my canning of plain tomatoes using the same timetable, which is pressure can hot-pack pints 30 min. - quarts 35 min. at 15 psi (at my altitude). Don't see where it is a risk at all... just common sense.