Posted on 22 February 2008 by

Botulism Real Threat in Canning Tomatoes

Canning TomatoesBy Michelle Fabio

In a sad reminder to tomato canners everywhere, 14 people were recently admitted to a Russian hospital, one of whom later died, because of an outbreak of botulism; the source was found to be homemade canned tomatoes consumed at a family gathering.

Botulism is an illness caused by the toxin “botulin” produced by Clostridium botulinum. As this toxin is one of the most powerful, for humans even one microgram can be lethal.

While botulism is a rather rare illness–there are usually fewer than 30 food-borne cases of botulism per year in the United States–and particularly in a food with high acidity like tomatoes, it can be deadly.

Here are a few things you can do to prevent botulism from affecting you and your family.

(1) As high temperatures kill the botulism toxin, follow The Tomato Queen’s advice when canning tomatoes.
(2) Before eating the canned tomatoes, boil them for at least 10 minutes.
(3) Discard any jars that have lost their airtight seal.

As the botulin toxin inhibits nerve function that leads to respiratory and musculoskeletal paralysis, symptoms of botulism can include dry mouth, slurred speech, double and/or blurred vision, drooping eyelids, difficulty swallowing, muscle weakness, difficulty breathing, vomiting, incontinence, and diarrhea.

If you are experiencing any of these, particularly within 6-36 hours after eating canned goods, get to the hospital immediately.

Source: Botulism, Canned Tomatoes — Russia (Khanty-Mansi)

21 Responses to “Botulism Real Threat in Canning Tomatoes”

  1. Nancy Bond Says:

    Excellent article that could potentially save people a lot of grief.

  2. michelle Says:

    Thanks Nancy; sometimes we forget that such basic dangers still exist.

  3. kim Says:

    Most of my can tomatoes will become spaghetti sauce. Based on your article, if I cook the spaghetti sauce to a low bubble boil for 10 minutes it should be safe?

  4. Chris W Says:

    I just started canning and i am having trouble. I canned whole tomatoes by the BALL BOOK. They started to bubble and produce gas. I threw them away. I didn’t want to mess with it. So i tried making my own sause. It been about a week and again now the sauce is producing gas. They seal well. And i cook them like i am supposed to. I don’t know what i am doing wrong.

  5. Asher Craig Says:

    ” How toxic is it? A little over a pound of botulin is enough to kill every human on Earth.” That’s some pretty toxic stuff!!

  6. Tom & Chris Says:

    Just canned tomatoes and some gars have water on the bottom why ,is it bad, how to stop it

  7. Jessie Says:

    my family just ate a can of bad tomatoe sause and is heading to the hospital now. my mom is a freak and thinks we got botulism because the sauce smelled rotten do u think its possible we got botulism

  8. vickie Says:

    I received a recipe from a friend that has been canning spagetti sauce for many years. I followed the recipe evrything went very well. I boile the tomatoes for several hours while I was cooking other things. I tasted the sauce it was excellent. I then boiled my jars and heated my lids as directions from ball said. I filled the hot jars with the beautiful still boiling sauce sealed set on the floor and the jars sealed right away and all looks well. Her recipe said not to move for 24 hours so I have not moved them yet. My husband tho upon learning of me canning these, said I was stupid because I did not add lemon juice before sealing. He said that the tomato sauce will be of no use because they will be poison when I open them. IS THIS TRUE?

  9. Michelel Says:

    Vickie, I use the same method for canning tomatoes. We have never had a problem with canning tomatoes this way. We only add a tsp of salt per quart.

  10. kim Says:

    Some points to be made:

    – botulism has no smell; so if your food smells bad, it’s not botulism. But if your food smells or tastes bad, DO NOT EAT IT PEOPLE!!

    – you absolutely should add lemon juice to your canned tomatoes, despite what others have done.

    – You also need to process it in a water bath/pressure cooker. Heat from the food will seal it without processing, but it is then NOT absolutely sterile. Even if you cook the crap out of it ahead. Your risk of serious bacteria thus increases. Yes, many people don’t and are fine. But that is HOW you get contamination. And become part of the few that do get ill.

  11. brad Says:

    wikipedia info…

    Although the botulinum toxin is destroyed by thorough cooking over the course of a few minutes,[1] the spore itself is not killed by the temperatures reached with normal sea-level-pressure boiling, leaving it free to grow and again produce the toxin when conditions are right.[citation needed]

    While commercially canned goods are required to undergo a “botulinum cook” in a pressure cooker at 121 °C (250 °F) for 3 minutes, and so rarely cause botulism, there have been notable exceptions such as the 1978 Alaskan salmon outbreak and the 2007 Castleberry’s Food Company outbreak. Foodborne botulism is the rarest form though, accounting for only around 15% of cases (US)[12] and has more frequently been from home-canned foods with low acid content, such as carrot juice, asparagus, green beans, beets, and corn. However, outbreaks of botulism have resulted from more unusual sources. In July, 2002, fourteen Alaskans ate muktuk (whale meat) from a beached whale, and eight of them developed symptoms of botulism, two of them requiring mechanical ventilation.[13]

    Other, but much rarer sources of infection (about every decade in the US[12]) include garlic or herbs[14] stored covered in oil without acidification,[15] chilli peppers,[12] improperly handled baked potatoes wrapped in aluminum foil,[12] tomatoes,[12] and home-canned or fermented fish. Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods.

    Oils infused with fresh garlic or herbs should be acidified and refrigerated. Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated. Because the botulism toxin is destroyed by high temperatures, home-canned foods are best boiled for 10 minutes before eating.[16] Metal cans containing food in which bacteria, possibly botulinum, are growing may bulge outwards due to gas production from bacterial growth; such cans should be discarded.

  12. Inaccurate Article Says:

    This article is inaccurate. Botulism isn’t cause by the tomatoes being acidic. It is caused when the tomatoes aren’t acidic enough. The spores will not grow and secrete toxins if the PH is above 4.5 so you should add vinegar to the mix and test the PH

    ALSO! Cooking the sauce may kill the spores, but will do nothing to eliminate the toxins created by the growing bacteria. Follow the book when canning and you will be safe.

  13. Chemist Says:

    The poster “Inaccurate Article” above is incorrect in saying that a higher pH is more acidic. A lower pH means a more acidic environment; high pH means a more alkaline environment. Hence, in a less acidic (higher pH) environment, botulism can thrive. Just wanted to clear up any confusion, should you decide to test the pH of your canned foods.

  14. Tammy Says:

    My canned tomatoes have working bubbles in the. one week after canning. i used vitamin c for the acid but what did i do wrong. thanks

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  16. Food tech Says:

    I have noticed puffing / spoilage of tomato paste (brix of around 28) packed in aseptic bags in bulk barrels.

    Is there any scientifically proven process to resterilize the spoiled paste and consume this one, without having any impact on food safety risk?

  17. Molecule-R, an Introduction to the Science Behind 40 Spectacular Recipes, by Molecule-R Flavors Inc | ANZ LitLovers LitBlog Says:

    […] The book begins by explaining all sorts of things you’d rather not know about the 2500 food additives that lurk in the processed foods that most people eat on a daily basis.  These additives consist of stabilisers, acidifiers, preservatives, enzymes and texturing agents and if you want to avoid them, as I mostly do, then you need to grow your own vegies, buy carefully and make your own meals from scratch.  Even if you’re not paranoid about it, it’s getting hard to buy a tin of tomatoes to make your own pasta sauce, because these days the tomatoes have mostly been ‘improved’ in some way.  Fortunately you can still buy Italian tomatoes that are just tomatoes and that saves the anxious process of bottling them (because I am a bit paranoid about botulism). […]


    I made home jarred tomatoes. Some jars separated with water on the bottom of the jars and tomatoes on the top. When I opened the jar of tomato it exploded the tomatoes out.
    I opened the jars with water on the bottom of jars cocked for 2 hours added salt 2 tablespoons of baking soda salt and some olive oil. Please tell me if I keep or throw away. Thank you

  19. Jill Hawk Says:

    Is it safe to freeze raw tomato puree? My sisters do it all the time.

  20. Marian Listwak Says:

    Curious: My understanding of botulism is that it survives in hermetically sealed containers, once the air hits it, the botulism spores multiplies rapidly, although it cannot survive in foods with an acidity of ~5.5 and lower. What apparently makes people sick is the toxin that it creates.
    So let us say that a jar of tomatoes that have a ph of 4.9 (botulism cannot survive) it looses its seal, which makes it no longer hermetically sealed, a small amount of mold forms on the top changing the ph to lets say 5.8, since the environment originally was one that botulism could not survive how would botulism form after the fact?

  21. Allyse Says:

    Here is the World Health Organization post on botulism – it is thorough and easy to read:
    Important take aways:
    1. Botulism bacteria produce spores are heat-resistant, but the toxin they release (which causes the disease) is destroyed by boiling. 5 minutes minimum, 10 to be sure.
    2. The bacteria itself is anaerobic, which means it grows in a lack of oxygen. Therefore, it is more likely to show up in ready-to-eat foods packed in low-oxygen containers.
    3. It does not grow in the refrigerator or in acidic conditions (pH 4.6 or lower).
    Learn something new every day!

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