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Is there any risk of botulism from refrigerator pickling or brining? (referring to both meat and slices of vegetables/fruit)

I've read about the subject a fair bit, and know the inherent risks with garlic in oil or items vacuum packed in the fridge for a long time.

However, I recently read about the use of nitrite salt in refrigerator brines for cured ham (a week-long process), which the author claimed was used to maintain the colour of the meat (which darkens without the nitrites) and also prevent botulism growth. But if all the ingredients were at 4°C before going into the fridge, what botulism growth could there be, especially in one week?

Is there something I'm not aware of, or this person uninformed?

3

Botulism thrives in high-moisture, low-acidity, low-salinity, anaerobic environments at between 50 and 130 degrees.

In your refridgerator pickles, you're:

  1. keeping cold
  2. adding acid
  3. adding salt

All of which should at least prevent the botulism from reproducing in great enough numbers to be toxic, if not outright killing it.

That's not to say nothing nasty can grow in refrigerator pickles — you're likely safe from botulism, however.

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You won't grow significant cultures of clostridium botulinum in temperatures below 50°F. On the flipside, unfortunately, refrigerator temperatures - while retarding growth - do not destroy the bacterium or inactivate or destroy its toxin.

The good news is, normal boiling inactivates present toxins, so even if you have c. botulinum present in the brine but boil it, the combination of both the inactivation of the toxin and the retardation of growth in low temperatures makes brining a pretty safe activity.

Furthermore, c. botulinum really dislikes high acid environments. Brines are usually rather acidic. It's important to note that it takes 250°F over three minutes to cause significant damage to clostridium botulinum. All other means, such as boiling at sea level pressure or refrigerating/freezing only slows culture growth and prevents the production of botulinum toxin. That means even if you cooked, boiled, and froze your food, leaving it out in the danger zone for too long still poses a risk. Obviously pressure-canning does significantly lower it.

  • You say It's important to note that it takes 250°F over three minutes to cause significant damage to clostridium botulinum but then say even if you cooked, boiled, and froze your food, leaving it out in the danger zone for too long still poses a risk How so? Cos surely the cooking it will take it over the 250 degrees, and then the freezing will be fine. Or are you saying you are fine at cooking stage, but the risk is the cooling down temps before freezing. – redfox05 Aug 17 '17 at 0:53
  • @redfox05 Recall that the boiling point of water is 212F. Bacterial spores can survive both boiling and freezing. – Nicholas Pipitone Feb 19 at 4:25
  • @NicholasPipitone When I said cooking, I was referring to methods like oven cooking which could go higher than boiling (212) and the 250 mentioned depending on oven temp. So in that case, would it all be fine, or still a danger? – redfox05 Feb 19 at 16:03
  • @redfox05 Even if the oven is 450F, the food is not. The temperature of the oven is just how fast it cooks. So long as there's still water in the food, the food is limited to 212F. If there's no water left, then you just have a powder that'll be shelf stable anyway, and cjay appears to be talking about generic "cooking", which is talking about cooking things that have water in them (Which is basically everything other than milk powder and spices). Without a pressure canner, you can't get non-dry food to ever be 250F. – Nicholas Pipitone Feb 20 at 10:23
  • @redfox05 If the food was theoretically 213F, and there was still water, then the water would boil until it was back at 212F (Boiling causes it to cool as sweating cools you down from a workout). Overall, cooking at even 450F will still keep the food in the 150s (Think steak temps), and trying to cook it for longer will just suck the food dry until it becomes tough jerky. Once it's dry, it'll then rise up to the temperature of the oven. See healthycanning.com/oven-canning for more explanation – Nicholas Pipitone Feb 20 at 10:24
1

AFAIK, you are not in significant danger of botulism in any kind of pickling or brining, refrigerated or room-temperature. The acid and/or the salt prevents the growth of botulism bacteria. Garlic oil is a specific danger because it has neither acid nor salt, and canned tomatoes because they don't have enough acid (yes, really).

That's not to say that you couldn't get other unpleasant microorganisms, but not botulism.

I am not a biologist or doctor, though. Hopefully we'll hear from one.

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