Comment by tripletao
2 years ago
The publication that I linked includes references into the peer-reviewed literature. The author has a PhD in microbiology, and is currently employed as a co-PI at the UC Davis Western Center for Food Safety:
https://www.wcfs.ucdavis.edu/linda-j-harris/
So while it's possible that she's mistaken, I think it's much more likely that you are. If you still think it's the former, then I'm open to review any references that you link.
> It's very clear that uncooked garlic stored in an anaerobic environment goes bad quickly, but if you have a good standard of cleanliness, cooking (part of the industrial canning process) almost certainly does retard the growth of bacteria.
You are continuing to assert this on your own authority. I linked an expert who explicitly stated that roasting didn't make it safe; but you seem to have disregarded this, seeming to imply--again, solely on your own authority--that it's still fine for "a few days".
Is there anything that would convince you to stop this? I understand the process feels safe to you, since you've done it hundreds of times without incident; but unless you'd consider p ~ 1/100 of a future incident to be an acceptable risk, that's not meaningful information.
The rest of your comment shows no familiarity with any modern canning process, and is filled with mistakes. But most fundamentally, are you not aware that botulism spores survive at 100 C? That's the reason why pressure canning is required for low-acid foods, elevating the boiling point of water to ~121 C. (That might be what you mean by "industrial canning", though many people pressure-can safely at home. That's what I meant by "elevated pressure" in my first comment. There don't seem to be any published methods for home pressure canning of garlic, but one could be developed.)
Normal roasted garlic still contains some water, which means it couldn't possibly have reached a temperature above 100 C at ambient pressure. So I don't see why you think that's safe. Perhaps the surface gets hotter and the spores are mostly at the surface; but in the absence of studies, and considering the downside, that seems like a remarkably bad gamble.
You and everyone in the food science field can convince me to stop this by providing a peer reviewed article indicating that roasting garlic does not get an internal temp hot enough to kill botulism (I will actually check this next time) and that botulism spores can inhabit the interior of the garlic. I would expect the latter to be false even if the former is true (the surface is the place all of these things grow). I also suspect that the former may be true - you roast garlic enclosed in foil and covered in oil, which are correct conditions for raising the internal temp past the boiling point of water without the water being able to completely boil off, and the sugars in the garlic do caramelize, indicating a relatively high internal temp (Fructose starts caramelizing at 110C).
You are asking me to follow the words of scientists who have not done the science. I am asking them to do the science. Particularly since their mechanistic theory has a huge hole: the actual processing of the vegetable. By the same standard, they should be telling you that cooked chicken and eggs are both unsafe - the raw product carries salmonella and the final cooked form is an ideal environment in which salmonella can grow.
You know as well as I do that scientists do not publish negative results. I haven't found anyone replicating growth of botulism in raw garlic, though, so I assume that the studies just haven't been done, not that anyone is hiding anything (this would be an interesting negative result). There have also been 0 food safety incidents, as far as I can tell, implicating cooked garlic stored in oil - it's all raw garlic.
With regards to this publication, I am mostly shocked that they are recommending acidification with no expiration date - they should be giving it a very hard timeframe of months if they want to hold themselves to a consistent standard.
It costs the FDA and USDA (and these people at UC Davis) nothing to say "conditions seem fine to grow bacteria so don't do it" without checking whether the process is actually safe with acceptable food handling procedures. I am fine with the FDA saying that - I have no plans to sell food - but the FDA has a lot of rules that are written out of an abundance of caution rather than out of need.
By the way - another way of making roasted garlic in oil is to "confit" the garlic completely in oil - submerge the garlic in the oil and cook it at 275F (~135C) for ~3 hours. This will absolutely, without a shadow of a doubt, raise the internal temp of the garlic to 135C, and if you handle it correctly, you will not re-introduce any bad bacteria. The FDA still won't let you sell it and that still goes against the UC Davis recommendations, despite being obviously sanitized. It is also delicious.
In other words, science is smart, but scientists can be dumb. Follow the science, not the scientists.
I don't think the study that you're asking for is likely to ever be performed. Even if the interior of an intact clove of garlic is free of botulism, pest damage, rough peeling, etc. might introduce it there. The goal of typical processing is to make the food uniformly safe, without relying on the initial distribution of the pathogens. For example, that's why the acidification method linked above applies only to chopped garlic, to ensure the acid penetrates all the way through.
The caramelized bits of roasted garlic almost certainly reached temperatures far above 121 C. The concern is the minimum temperature though, not just the surface temperature.
I'm not sure how your analogy with chicken is supposed to work. If you cooked chicken, submerged it in oil, and then incubated at room temperature for a few days, then I definitely wouldn't eat that either. The problem isn't the initial population of C. botulinum; it's that they multiply under the anaerobic conditions of the oil.
Likewise, I'm not sure what you think is wrong with their advice on the acidified garlic. The botulism simply won't grow at low pH, no matter how long you wait. The taste and texture will eventually become disgusting, but that's not a safety concern.
You seem to have the idea that cooking fully sterilizes food. That's not correct; it decreases the population of pathogens, but not to zero. So the cooking potentially makes the food safe to consume immediately (since the dose makes the poison, and the dose is very small). But if the food is incubated under conditions where the bacteria can grow, then the dose gets exponentially bigger and the food becomes unsafe. Methods that rely on perfect sterility (like pressure canning) achieve that by applying heat when the food is already in a closed container, and are assumed to lose that sterility once the container is opened.
Water-free garlic in oil should be safe at room temperature, and that publication gives directions for dried garlic in oil. I'd guess that confit would be safe too, and I'm not sure why you think the FDA would forbid it. (Note that it would be safe because of the low water activity, meaning that even if botulism spores are present they can't multiply. It would not be safe because it's "sanitized".)
> I'm not sure how your analogy with chicken is supposed to work. If you cooked chicken, submerged it in oil, and then incubated at room temperature for a few days, then I definitely wouldn't eat that either. The problem isn't the initial population of C. botulinum; it's that they multiply under the anaerobic conditions of the oil.
Let me spell out the analogy: The problem with chicken isn't long-term presence of a bacteria colony (botulism), it's presence of salmonella. Salmonella doesn't need days to become a problem - it's a problem immediately. Chicken when raw is a great environment for salmonella. Chicken when cooked is a great environment for salmonella - in fact, there are numerous food safety incidents that occur when people use the same utensils on raw and cooked chicken, transferring the bacteria. Hence, the only reason it is safe to eat the cooked chicken is because you kill (enough of) the salmonella during the cooking process.
Conversely, he document you cited makes the claim that raw garlic is a great environment for botulism, and so is roasted garlic, and does not address whether the cooking process kills the bacteria. In fact, it makes the claim by implication that there is no roasting process that kills the bacteria. As far as I can tell, these claims are made without any actual experiment, and it is simply enough that the environments before and after processing are good for harboring the bug.
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