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I'd like to pressure can tomatoes without adding acid as recommended by the USDA (and outlined here). The reason being is, imo, the additional acid ruins the flavor.

My understanding of the official recommendation is that it specifically relates to food safety for water bath canning. This is further supported by statements like this:

High acid foods can be safely canned in a water bath canner. Low acid foods may need the addition of acids like lemon juice or vinegar to acidify them enough to be canned in a water bath canner. Non acidic foods require the pressure canner.

There are many recipes for safely canning low acid foods using a pressure canner but despite the above statement and a large volume of research to support it, I've been unable to find a single authoritative recipe outlining a safe procedure for pressure canning tomatoes without acid. I did however find a plethora of other threads about this very topic with nothing conclusive and no strong consensus, e.g.:

How can I safely can tomatoes using a pressure cooker without adding any acid? Can I simply follow the procedure for canning another low acid vegetable like carrots or green beans? Like 10 lbs pressure / 25 minutes? Or maybe err on the side of safety and increase time and/or pressure?

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According to Putting Foods By, 25th ed. (1982), you can fill tomato jars with just hot boiled tomato juice rather than requiring additional acid, and then pressure-can them:

  • 10lbs pressure / 40 minutes for skinned whole tomatoes
  • 10lbs pressure / 15 minutes for sliced or diced tomatoes

... with some adjustments depending on jar size.

However, their extensive (11 large pages) section on tomatoes notes that whether or not acid should be added when pressure canning is controversial.

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    Thank you very much for the great reference. My question then would be, why is it controversial? I understand that the acidity levels can vary but I think we can agree that any tomato substance will be more acidic than something like corn or carrots which are low acid. And canning those things without additional acid is somehow not controversial at all? This is where I get lost... is there a variable I'm missing in this?
    – But those new buttons though..
    Aug 30, 2019 at 2:45
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    Personally, I don't think there is. I think the various health authorities tend to go overboard with tomatoes because, in the US, there were several botulism deaths related to home-canned tomatoes in the 60's and nobody has forgotten.
    – FuzzyChef
    Aug 30, 2019 at 15:56
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    The book does not say why it's controversial.
    – FuzzyChef
    Aug 30, 2019 at 16:06
  • I am curious to know if you have tried it and, if so, how it turned out. As I understand it, 240 ° should kill everything in it. I am about to can 7 quarts of raw, unpeeled, quartered Roma tomatoes with nothing added. (No acids, salts, or water). I am trying 12 pounds of pressure (altitude ~500 ft) for 30 minutes. I will try to remember to report back with results.
    – Bob
    Aug 17, 2020 at 0:58
  • @Bob - How'd it go? You still with us? btw, I just canned 20 pints puree @ 11lbs for 25 minutes. Seeing as the official recipe for Spaghetti Sauce without Meat calls for a combination of tomato and lower acid vegetables for only 20 minutes, it seems reasonable to assume this would be safe.
    – But those new buttons though..
    Aug 26, 2021 at 3:12
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I have been canning tomatoes for 30 years with no acid of any kind. I have never had a problem with any jar. I do not use anything in the tomatoes as a preservative. I pressure can my sauce as in the book Putting Foods By.

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  • Thanks for participating on the site. However, I would suggest that food safety questions are better answered from a scientific perspective, rather than from personal experience. Acidity in tomatoes varies quite widely, and safety procedures need to be fully explained to be valuable.
    – moscafj
    Jul 25, 2022 at 15:23
  • @moscafj This answer does cite a source, one that as far as I know is well-regarded.
    – Cascabel ♦
    Jul 25, 2022 at 16:10
  • @Cascabel I think we usually like bit more by way of explanation. This answer doesn't really answer the question, rather, it shares a personal experience.
    – moscafj
    Jul 25, 2022 at 16:13
  • @moscafj Wanting more explanation is fine; you flagged this about food safety, though, and I do not think that there is a food safety-related concern here that requires moderator action. It's definitely not n=1; it cites an authoritative source.
    – Cascabel ♦
    Jul 25, 2022 at 16:21
  • Sherry, would you be able to share the canning process you use from Putting Food By?
    – Cascabel ♦
    Jul 25, 2022 at 16:21
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There is a recipe from the USDA for canning zucchini with tomatoes that is not acidified. It is 11lbs pressure for 35 minutes. If that is sufficient for tomatoes with zucchini, I cannot imagine why it wouldn’t be for tomatoes alone.

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  • Different ingredients carry different potential hazards, which in turn equates to varying levels of risk. Otherwise, why conduct raw material hazard analyses at all? Please take a look at some industry literature on this subject. Although not specific to food manufacturing and processing, there is a very well composed industry white paper I'm fond of referencing from the biopharmaceutical sector, it's very thorough and educational, and the methodologies involved are mostly synergistic (Ajinomoto, among other reputable QA teams, co-authored the publication); ...
    – Arctiic
    Jul 9 at 3:34
  • RAW MATERIAL RISK ASSESSMENTS backup. And here is one specific to the food processing industry: [Ingredients Hazard Analysis and Process-Step Hazard Analysis: Why Separate the Two? ](food-safety.com/articles/…) backup
    – Arctiic
    Jul 9 at 3:35
  • @Arctiic isn't this just a question of the acidity of the items being canned and the amount of time/heat it takes to make an item of that acidity safe for long term storage? Is there some other sort of assessment you believe the USDA performs? I looked through the link you shared, but I'm not sure how it relates to this argument.
    – Catherine
    Sep 10 at 19:29
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Y'all are speaking my language. I've called my extension office with this same question and basically was told we add acid because that is the tested approved way. Sigh. When I hit them with the logic that we don't add acid to low acid foods when pressure canning or to the approved spaghetti sauce why do we need to add plain tomatoes...it literally makes no sense. They told me it's because tomatoes can lose acidity over time when canned...which I asked again...then why don't we add acid to other low acid foods. They didn't have an answer beyond that is what is approved. I'm convinced it's overkill.

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  • Yeah, unfortunately they can only give you existing guidance rather than derive guidance de novo.
    – Catherine
    Sep 10 at 19:30

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