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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?
    – Eaten by a Grue
    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.
    – Eaten by a Grue
    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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My understanding comes from a lifetime of bottling (UK equivalent term for canning), and helping my mother....I do not add acid to fruit or vegetables if I pressure bottle. I consaulted a local microbiologist who endorsed my opinion by saying that water baths are the main culprit where botulism is concerned. Any problems with pressure cooking bottling probably derive from user error in sterilisation of equipment, proper fitting lids and screwing down, and timing etc.

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