Yes, if the tested and approved recipe I'm using requires its addition. Most of the recipes for tomatoes require the acidification step whether using BWB or PC.

Dave

I'm just curious... if it's required for toms in a PC, why not for all veggies?

The NCHFP provides approved guidelines for canning acidified tomatoes. Acidified tomatoes can be processed in a boiling water bath or a pressure canner.

Tomatoes must be canned as other vegetables in a pressure canner as they are considered low acid vegetables. The NCHFP does not provide processing times for tomatoes..only acidified tomatoes.

One can only speculate as to the reason why. My theory is that tomatoes have always been processed as acid and have recently been discovered to be low acid. So to maintain continuity and avoid confusion they opted to continue providing guidelines for tomatoes as acid vegetables which requires acidifying them.

Zeuspaul

zeuspaul

My husband and I are both concerned that the lemon juice will change the flavor of the toms, and hence, the sauce I make from them.

Because of the natural acidity levels of most vegetables - below 4.6 pH. Tomatoes, as a class, are considered are border-line pH. Article linked below explains it in more detail.

Dave

Here is a link that might be useful: Food Acidity and Processing Methods

"concerned that the lemon juice will change the flavor of the toms"

Thus the option of citric acid. Some do claim the lemon juice alters the taste, most don't as the addition is minimal. Citric acid is a tasteless approved alternative.

Dave

I'm a little confused about this as well. If you pressure can tomatoes the same way you would any other low-acid vegetable, why would you need to add acid? I've always WB'd my tomatoes, but plan to pressure can this year. I've never used the citric acid and am a little concerned it will change the taste of the tomatoes.

I found the following quote at the University of Minnesota site. Note the "or" in the last sentence.

"Researchers at USDA and at the University of Minnesota have found that most underripe to ripe, cooked tomatoes have a pH below 4.6. Unfortunately, a few varieties may have a pH above or close to 4.6. These include Ace, Ace 55VF, Beefmaster Hybrid, Big Early Hybrid, Big Girl, Big Set, Burpee VF Hybrid, Cal Ace, Delicious, Fireball, Garden State, Royal Chico, and San Marzano. Some of these are grown for commercial purposes and are not found in home gardens. However, safely canning these varieties requires additional acid for water bath processing or a pressure canning process similar to low acid vegetables."

Here is a link that might be useful: University of Minnesota

Dave,

I think you posted while I was composing my post. :) You answered part of my question - thanks!

I'm a little confused about this as well. If you pressure can tomatoes the same way you would any other low-acid vegetable, why would you need to add acid?

Because as I said above other vegetables are considered high acid, not low acid. They are well down into the acid side of the scale. So they are safe to can without additional acid. They must still be pressure canned because of density and botulism issues (different reasons for PC requirement).

But tomatoes (which are a fruit after all ;) are not rated as high acid. They are borderline at 4.6 or higher so because of the existence of many varieties of tomatoes with a pH of 4.6 or higher, tomatoes as a class are rated as borderline and so must be acidified whether PC or BWB is used.

Think of this this way. To be safe - the desired finished pH of the product is approx. 4.0 to maybe 4.2. Many things will be much lower on the scale so even more acidic even 3.0 but you can't be higher on the scale. Most all other vegetables (mixed vegetables is an exception) are already in the 4.0 range. Tomatoes aren't. They are 4.5 to 4.9 depending on variety. So you have to add acid in the form of lemon juice (bottled only), citric acid, or vinegar (which is yecky) to get them down into that 4.0 range.

Does that help?

Dave

Looks like I did it again. ;)

Dave

If you processed tomatoes without added acid and pressured canned them as you would other low acid vegetables, you would have to process for up to 100 minutes compared to the 20 minutes with the acid. The result would be an undesirable product.

The processing time for tomatoes and zucchini is 35 minutes (no added acid). Zucchini is lower acid than tomatoes so the mixture is lower acid than tomatoes.

Why would the processing time be so much greater for tomatoes than it is for tomatoes with zucchini?

Tomato sauce would be higher because of heat transfer issues. However I would think that the processing time for tomatoes would be the same or less than the processing time for tomatoes and zucchini.

Zeuspaul

Here is a link that might be useful: NCHFP tomato and zucchini recipe

I agree, some thing need to be explained.

Thanks Dave - looks like you *did* do it again. :)

I really hate to be dense but...

If I have this right, the lower the PH the higher the acid, right? If this is wrong, my whole line of reasoning is off, but please bear with me.

The ph of peas is somewhere around 6.0, which would make them lower in acid than tomatoes. Am I right so far? But you don't add acid to peas when you can them. OTOH, the ph of tomatoes is in the 4.3 - 4.9 range, but you still need to add acid.

I'm confused.

I always use the USDA guidelines for canning so will add the citric acid, but I also like to know how things work. And my logic says that to add acid to a food that is higher in acid content than another food to which you do not add acid is just....well...confusing. LOL

I don't think peas are that low a 6 pH.

Thanks, I was aware of that from reading recommemed sites online. I just wondered why toms, when PCd, still needed acid added. I can't find citric acid anywhere where I live. Ordering it online is expensive what with S&H charges.

To: willowdee

That doesn't make sense to me except perhaps the time to safely PC toms is unknown. If I had to guess I would do them for the same time other watery veggies were done, such as summer squash. The consistency is about the same unless the toms are boiled down into sauce. Maybe give them an extra 5 minutes in the PCer.

To: willowdee

From what I've been reading on the sites people here recommended tomatoes are the only acid veggie (really a fruit) we can. Their PH is lower than everything else. All other veggies are less acid or higher on the PH scale.

I've been pondering this question all day. :) Have I mentioned I tend to be a bit obsessive sometimes???

Anyway, I've come up with a theory but have no idea whether it is valid or not. I'm thinking maybe the reason for the added acid is not so much that you can't can tomatoes without it, but to shorten the processing time. Processing time for tomatoes is 25 minutes @ 10 lbs. pressure. If they were processed for any longer, I'd think they'd turn to mush. Does that make sense to anyone else?

This will be my first time PCing tomatoes. I've always loved them WBd and I really hope the taste will not suffer by PCing them. It will certainly save time and seems safer to me.

I just bought 100 pounds of tomatoes, so I guess I'm about to find out. :D

Tomatoes can be canned as low acid vegetables or as acid vegetables. If they are canned as acid vegetables they must be acidified to bring them solidly into the acid side of 4.6.

If they are canned as low acid vegetables they must be pressure canned. The NCHFP does not provide processing times for canning tomatoes as low acid vegetables.

If they are canned as acid vegetables they must be acidified. If you acidify them you have the option of boiling water bath or pressure canner. The NCHFP provides processing times for acidified tomatoes.

Zeuspaul

I can explain it all later when I have time. Sorry, but I just got home from a meeting and have dinner to cook.
If you search you may be able to find the explanation on this from last year if you are in a hurry.
All veggies are LOW acid. There are no high acid ones unless you acidify them. That is why highly pickled ones can be done in the BWB.
Yes, all tomatoes both in the pressure canner and BWB must have added acid added to them.

This may sound completely goofy but is ascorbic acid approved for acidifying tomatoes? If so, could a person crush Vit C tabs and use them?

Ascorbic acid, as mentioned before is just a form of vitamin C. Vitamin C pills, have a mixture of cornstarch and other binders, so using the vitamin C pills isn't as exacting and can give foods an off color and/or flavor, as you have no control over how much ascorbic is in each pill. It has very little in acidic strength to acidify any foods. Its primary use is for an antioxident. Citric acid, which is true form of acid, is meant to acidify and cannot help prevent oxidation. Lemon or other citrus juices have only a small amount of ascorbic, while the citric level is much higher. These two acids, are VERY different, and are not suitable for each others uses. Tomatoes, are such that acidity can vary greatly from tomato to tomato, plant to plant and field to field. Some types are higher in natural acid than others. Also, weather, soil conditions, fertilizers and many other factors affect the natural acidity level. Thats the main reason for tomatoes to get citric acid added when doing home canning, because there is no easy way to know if the natural acid level is at its optimum. Because this acid can actually increase in strength, just like salt, when your boiling down a watery tomato sauce to make it thick, you could add the salt and citric acid to each empty jar before they are filed. 1/2 teaspoon of each (salt and citric) per quart. If you prefer salt free, there again, you do not need to add any salt. I add the salt and citric to the empty jars just prior to filling them. In this way, you get the exact amount you need, without any concern that it is increased in strength due to boiling out the water in the sauce.

Drats! Now my head is spinning too. I thought sure I had a handle on this - finally - after all the reading I did in the past few days. But after more reading my old brain just blew smoke out my ears. Between all the low-highs and the high-lows and acid and non-acid and the contradictory claims from different sources it makes no sense.

I know Linda Lou can explain it when she gets time or we can always write to Dr. Andress and ask her. She is very good about answering questions.

Meanwhile, I'll just keep doing what the recipe tells me to do.

Dave

PS: citric acid from canningpantry.com is very reasonable. Just bought a new supply.

To: willowdee

Please report back and let us know. :)

To: digdirt

Yes, the price for Citric Acid was only $2.99 but the shipping was $8.16!!!!!! Total for the container w/shipping was $16.15 - never mind. I'll use the lemon juice and if it ruins the tomato flavor I'll omit it and go back to the way I always did them. Since they're used for sauce and always boiled at least 20 minutes or more I wont worry about botulism.

greenhouser, I processed my first batch in the PC last night. I haven't tasted them, but I'm taking Dave's word for it that the citric acid won't change the taste. I did learn one thing - if you PC tomatoes with no added liquid like I do, you have to pack them tighter than you would most other veggies. I lost quite a bit of liquid in each jar and wound up with something little less than a quart in each jar. Today, I'll be doing the rest, but will pack a few more tomatoes in each jar. They do look really pretty, though. :) Does my heart good to see those jars full of food stacking up. Ah, the joys of canning. LOL

Ok, I wrote to Dr. Andress and here is the reply I got.

Thank you for visiting the National Center for Home Food Preservation.

> question -> When pressure canning plain tomato products, why is acidification still required when it is not required for other pressure canned vegetables that are less acidic than tomatoes?

Thank you for checking. This is the statement about acidification on our website, below. The last sentence notes that the BWS and PC process times are equivalent:
If a procedure from the USDA Complete Guide to Home Canning for canning tomatoes offers both boiling water and pressure canning options, all steps in the preparation ("Procedure") are still required even if the pressure processing option is chosen. This includes acidification. The boiling water and pressure alternatives are equal processes with different time/temperature combinations calculated for these products.
http://www.uga.edu/nchfp/how/can_03/tomato_intro.html

In other words, the pressure process times are the equivalent to the boiling water heating; these pressure processes are not botulism processes like are calculated for low-acid foods. In a similar vein, there are pressure processes for many of our fruit products, but they are not botulism processes simply because they are in a pressure canner. Those are the equivalent to the acid processes in a BWC for each of those fruits.

You can use a little bit of acid in tomatoes to keep the process heating shorter like boiling water, which helps preserve quality and nutrients. It would take enough acid to create a pickled product for lower the other vegetable pHs to a boiling water-safe level. Non-acidified pressure processing times for tomatoes would most likely be longer than those we published as boiling water equivalents.

I hope this helps; I am not sure how many more ways to say it! let me know if this doesn't do it.
Elizabeth Andress
--------------------------------------
Elizabeth L. Andress, Ph.D.
Project Director, National Center for HFP
Professor and Extension Food Safety Specialist
Department of Foods and Nutrition
The University of Georgia
208 Hoke Smith Annex
Athens, GA 30602-4356
Phone: (706) 542-3773
FAX: (706) 542-1979
-----------------------------------------------

Dave

Ken,

Thanks for the reply on the Vit C tabs. I figured they wouldn't work but thought I'd give it a shot.

Since the majority of my processed toms are later used in sauces, chili, etc. I don't notice any taste issues when using lemon juice. But that's me. =)

Citric acid is added to some commercially canned tomatoes, and sometimes they also add calcium chloride. The latter is to keep texture if the tomatoes are whole or chopped. Citric acid can affect taste, if you dislike acidic foods. One way to counteract that is to add a small amount of sugar. It will not nutralize the extra acid, but will give your taste a little closer to something like "Prego' which has a lot of sugar added. Something that people may not think about is the FUTURE. Yes, a 1 pound bag of citric is cheap with costly shipping, but wht not buy FIVE POUNDS or even TEN POUNDS. Doubling or buy bigger amounts are not usually double the costs. Citric has no expiration date and if your canning tomatoes every year, the measly small 1 pound of it will not last very long. I don't buy any canning supply in small amounts, as I always need it for canning and just hate to run out in the middle of a procesing.

To: digdirt

Yes, the price for Citric Acid was only $2.99 but the shipping was $8.16!!!!!! Total for the container w/shipping was $16.15 - never mind. I'll use the lemon juice and if it ruins the tomato flavor I'll omit it and go back to the way I always did them. Since they're used for sauce and always boiled at least 20 minutes or more I wont worry about botulism.

Heavens yes - buy the bigger containers, not the small $2.99 one then the shipping is appropriate. As Ken said, it keeps forever. I bought my last batch some 8-10 years ago. ;)

I'll throw this into the mix but please note that is is NOT approved.

If you find you just can't handle the lemon juice or citric acid additive for some reason (and I honestly believe you will not even know it is there), then at least consider using Fruit Fresh. It does contain some citric acid along with ascorbic acid (predominant acid ingredient) and is readily available at any grocery store.

I repeat - its use is not approved as a replacement but is does provide some acidification. Just an under-the-table suggestion. ;)

Dave

Dave, thanks for contacting Dr. Andress. Now, *that* makes sense. Now I can stop obsessing. LOL

Thanks Dave.

As Elizabeth said, the ones in the PC and BWB are equivilent processing times. Folks don't normally want to PC tomatoes for a longer time. It is based on the "general" public. It is easier and faster to just add the acid. It would take a long time for the heat to penetrate the tomatoes in the pressure canner that most people would not want to do that.
All the commercial tomatoes have citric acid added.Fruit fresh is only for color preservation, not for adding acidity. Do not use it instead. It must be citric acid or bottled lemon juice.
The Minnesota guidelines are not safe to rely upon for tomatoes. One thing, most of us are not in Minnesota. Secondly, this is their own independent study. This is not the USDA standard testing.( The National Center For Home Food Preservation are the ones to rely upon. They are the leading authority when it comes to canning. Elizabeth Andress wrote the USDA guidelines.) Our soil will be different than theirs. If you grow the same tomatoes in your garden and I grow them in mine they ph level can be totally different.
The canning times for the other veggies are based not only on ph, but density. It depends upon how the cells of the veggies absorb the heat in the pressure canner. Denser things take longer to process. For example, green beans in water will heat faster than a jar full of just packed tomatoes. Same reason the zucchini and tomato mixture is processed with no acid added. The juice from the tomatoes, the way they are diced, etc. all make a difference in heat penetration .
Same reason tomato juice doesn't take as long to process as whole tomatoes. The juice is thinner and less dense.
So, that is most of the reason behind tomatoes taking so long. We find that the crushed tomatoes result in the best texture, faster times, etc.
There is a comparable time, but that is for tomatoes packed in water. Who wants to fill their jars full of water with tomatoes ???
If you raw pack them, then it does take 85 min. in the BWB canner. So, when we teach canning lessons we have them do the crushed tomato version from the NCFHFP. You crush and heat some of the tomatoes first, then keep adding the rest of the tomatoes to the pan and heat them all.
The PC is supposed to have a higher nutrition value than the BWB canned tomatoes.
If you think them too tart, some folks add a pinch of sugar. I don't even notice the tartness of the added acid to tomatoes.
I hope I answered everything. If not, then ask me again.
Things are CRAZY around here now !
Oh, and the thing about boiling them first before you eat them. Well, if botulism is there, think about you opening that jar, touching the lid with botulism on it. Then, maybe dripping it on the counter. Just not really that wise to use boiling as insurance in my personal opinion. Either you processed them correctly and they are safe or they are not safe. So, I suggest do it correctly and no risk involved.

digdirt

I plan to use some of the Fruit Fresh since the guy at the store said it does the same thing as citric acid, so I bought it. I know *now* they're not the same thing, though they may both keep fruit from browning.

The costs are getting out of hand with this - and my canner still isn't even here yet. I'll never order anything online from Wal*Mart again. My string-beans are starting to come in and God only knows where the canner is. This being a semi-rural county with many farms and country/farm families, you'd think canners and canning supplies would be easy to find .... WRONG! :(

linda_lou

What is the safe time for quartered toms or crushed toms with lemon juice in a PC?

greenhouser

This might help...

Here is a link that might be useful: NCHFP

It looks like willowdee got it right. Tomatoes can be canned without acid but the quality suffers. Adding acid reduces the processing time and results in a less *mushy* product.

Tomato sauce, puree and paste seem to fall into a different catagory. The NCHFP doesn't require the addition of acid to paste. However it does require the addtion of acid to sauce and puree.

S&W doesn't add acid to tomatoe sauce, paste or puree. They add acid to all of their whole, sliced and crushed tomato products.

Zeuspaul

Here is a link that might be useful: S&W sauce

All the commercial tomatoes have citric acid added.Fruit fresh is only for color preservation, not for adding acidity. Do not use it instead. It must be citric acid or bottled lemon juice.

I know you are correct Linda Lou but I figure it is better than not adding anything at all. greenhouser said she would just do them as usual - with no acidification. I think the Fruit Fresh would be better/safer than just doing that.

It does contain some citric acid but there is no way to determine how much acidification it would supply. I offer it as a "it's better than doing nothing" suggestion. ;)

Dave

For the cost of shipping at over $8.00 for a SINGLE and SMALL order of citric... It makes more sense to buy 4 (whatever the weight?) of them or more. I would expect the S&H would be same for 4 as it is for just one. Citric acid will not expire or spoil, like ASCORBIC acid. Ascorbic acid cannot be used to increase acidity as its not suitable for that use as I stated before. Adding it to 'increase safety' in canning tomatoes would require about half a cup or more per quart. By then ascorbic would cause a bad taste to tomatoes. People that work in, or own stores can tell you anything you like to hear, even if its very wrong. I would more than just doubt a statement about sustituting an acid for an antioxident. If you are not sure about the statements above, see/read the following site links:

http://en.wikipedia.org/wiki/Ascorbic_acid
http://en.wikipedia.org/wiki/Citric_acid

Why not add bottled lemon juice then and not citric acid crystals ?
If you want to PC the crushed tomatoes, here is how to do so :

How do I? ...Can Tomatoes
--------------------------------------------------------------------------------

Selecting, Preparing and Canning Tomatoes
Crushed Tomatoes (with no added liquid)
A high-quality product, ideally suited for use in soups, stews, and casseroles. This recipe is similar to that formerly referred to as "Quartered Tomatoes."

Quantity: An average of 22 pounds is needed per canner load of 7 quarts; an average of 14 fresh pounds is needed per canner load of 9 pints. A bushel weighs 53 pounds and yields 17 to 20 quarts of crushed tomatoes-an average of 2¾ pounds per quart.

Please read Using Pressure Canners and Using Boiling Water Canners before beginning. If this is your first time canning, it is recommended that you read Principles of Home Canning.

Procedure: Wash tomatoes and dip in boiling water for 30 to 60 seconds or until skins split. Then dip in cold water slip off skins, and remove cores. Trim off any bruised or discolored portions and quarter. Heat one-sixth of the quarters quickly in a large pot, crushing them with a wooden mallet or spoon as they are added to the pot. This will exude juice. Continue heating the tomatoes, stirring to prevent burning. Once the tomatoes are boiling, gradually add remaining quartered tomatoes, stirring constantly These remaining tomatoes do not need to be crushed. They will soften with heating and stirring. Continue until all tomatoes are added. Then boil gently 5 minutes. Add bottled lemon juice or citric acid to jars (See acidification directions). Add 1 teaspoon of salt per quart to the jars, if desired. Fill jars immediately with hot tomatoes, leaving ½-inch headspace. Adjust lids and process. Recommended process times are given in Table 1, Table 2, and Table 3. (Acidification is still required for the pressure canning options; follow all steps in the Procedures above for any of the processing options.)
Process pints or quarts in a pressure canner for 15 min.
Use 11 lb dial gauge canner, 10 lb. weighted gauge canner, unless you need to adjust for higher altitudes.
*****************
This is the method I like to use. I have 2 pressure canners, so not only can I stack pints, but I can do 2 canners at once.

Why not just do a small batch with lemon juice then use a can as you normally would to see if you detect an off flavor?

Excellent idea. Not every likes acidic food and not everyone likes any kind of lemon flavor.