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Today I’d like to address the recommendation to use a non-anaerobic fermenting vessel and pour oil on top of the brine instead of using an airtight fermentation system.
Initially, I thought this might be a good idea for those who have stated they can’t afford a Pickl-It or a Harsch, so I started doing more research. Then I found that oil can actually give dangerous bacteria that can cause illness a safe harbor, away from the dropping pH in the brine. This allows the nasties you don’t want in your ferments to have a way to survive.
If you check a variety of county extension agency websites, the botulism issue is why oil-preserving methods are no longer recommended for food preservation. The only safe way to preserve things in oil is to heat the product to a temp high enough and long enough to kill the botulism toxin- it’s almost like a form of pasteurization.
Oil gives an anaerobic environment without the pH drop that is the ideal environment for botulism to grow. By only having a brine ferment, the botulism comes into contact with the dropping pH and is killed. When you add the oil, you give the botulism a place to hide and thrive, producing its toxin.
Botulism is a serious illness caused by a toxin called Botulinum that is produced by several different types of bacteria- Clostridium botulinum, C. butyricum, C. baratii and C. argentinense. The toxin that the bacteria produce is tasteless, odorless and colorless. Because it multiplies readily in soil, it can be on vegetables. That’s normally not a problem for eating fresh or cooking because the oxygen in the air keeps it from mutiplying and producing the Botulinum toxin that makes people sick- from what I can gather, eating the bacteria themselves isn’t usually dangerous, it’s the toxin they produce that can be deadly.
In an anaerobic ferment, the pH drop kills them so the toxin can’t be produced. Heat is required to kill it- you have to boil the product for 20 minutes to inactivate the toxin and kill the bacteria in home-canned food. Botulism is not a threat in a properly prepared ferment with a low pH since the bacteria are killed before they can produce the toxin. However, when you give it a harbor in oil combined with a low or no-oxygen environment, it starts reproducing and churning out toxin. It can produce enough toxin to make someone ill in 2-3 days. That means there could be enough to make you sick before you start consuming the ferment.
So using oil does present a risk in giving the bacteria not just a toehold but an anaerobic place to thrive so that it can produce the toxin. While botulism isn’t very common, it isn’t an easy illness to get through, either, and it normally requires hospitalization and weeks of recovery. The ventilator is credited with dropping the death rate from botulism, but untreated the fatality rates reach 60%. It obviously isn’t something to be trifled with.
The other part of the equation is that if you’re using decent quality olive oil and enough of it to actually seal off the brine because you see the value of truly anaerobic fermentation, you’re not going to take too many ferments before you could have paid for a Pickl-It. If you’re a traditional foodists who ferments regularly, it’s a penny-wise and pound-foolish choice. If I used a half-cup of oil per ferment, at the price I pay for olive oil, I could pay for a 2L Pickl-It including shipping in less than 20 ferments. Around here, that’s less than six months. In the summer, it’s even less time than that. I’d rather put the money towards the Pickl-It and not risk the botulism.
I believe you could also run the risk of the oil going rancid before the ferment is completely consumed, making you throw out batches. You also have to consider the flavor and texture changes that will be caused by the addition of oil. In talking to some people who have tried it recently, they weren’t happy with the final product compared to a ferment without the oil.
So in conclusion, even if we could find evidence of oil being used more than 250-300 years ago, I would still avoid it due to the botulism issue. Being paralyzed and hooked to a ventilator for a couple of weeks doesn’t sound fun… or cheap. I’d rather use a Harsch or a Pickl-It and avoid the oil.
It wasn’t too many years ago that people regularly died of illnesses caused by improperly stored food. I can recall my great-grandmother discussing it; she was careful to ensure it wouldn’t happen in her own kitchen. I don’t want to be lax in my recommendations and cause harm to someone. So the bottom line is that between the issues with the potential for botulism and the cost, I will stick with my Pickl-It and my Harsch instead.