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Botulism concerns re infused oils and confit

Charcuterie

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#61 Jenni

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Posted 02 August 2011 - 12:56 AM

I used to use fresh herbs. But now I use dried, I find that is safer. I always store it in the fridge. With fresh herbs I used to notice a slight film at the bottom of the container, I haven't seen that with the dru herbs.

Haven't had the problem with garlic olive oil.

I heat the oli to about 220-250, five minutes or so, let it cool down then strain and put it in a ball container.



Two things:

*If the oil got contaminated with botulism it would not be visible, so visual clues such as you noticed are not helpful. I don't think dried or fresh herbs would make a difference in this case.

*I'm pretty sure someone here once explained that even if you heat the oil itself up to a high enough temperature to destroy the spores, the stuff in the oil does not heat up to that same temperature so it does not mean that the product is safe. Something about waters boiling point being 100 and you can't make water go higher than that unless you heat it under pressure? God I don't know, someone help me out here. I remember that the key point was that heating it up (not under pressure) is not helpful.

#62 MaxH

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Posted 02 August 2011 - 09:00 AM

I used to use fresh herbs. But now I use dried, I find that is safer. ... Haven't had the problem with garlic olive oil.
/ I heat the oli to about 220-250, five minutes or so, let it cool down then strain and put it in a ball container.

Zaskar, evidently you are thinking of hazards different from the topic of this thread. With botulism you don't, in reality, empirically have any idea whether anything is "safer" or not, nor whether you've "had the problem with garlic olive oil," unless you catch the food poisoning, in which case you may improve your chances of survival beyond the classic 50-65% with prompt medical attention for the strange neurological symptoms you'll experience. For preventing botulism, the heating-the-oil comment above repeats a gross misconception addressed before in this thread and elsewhere in eG.

Folks -- please, please, read this whole thread! before repeating misconceptions already addressed here.


There are different strains of C. Botulinum, with different low-temperature-resistance

Yes, I have that information in depth, in print, and it's behind my comments here. For example, selections from much more info in a current standard authoritative physicians' reference (the professional Merck Manual, emphasis to distinguish from other Merck pub'ns with related titles):

Seven ... antigenically distinct toxins are elaborated by the sporulating, anaerobic gram-positive bacillus C. botulinum. Human poisoning is usually caused by Type A, B, E, or F toxin. Type A and B toxins are highly poisonous proteins ... Exposure to moist heat at 120 C (248 F) for 30 min kills the spores [SEE upthread comments on the persistent hot-oil misconception about this, and why -- MH]. Toxin production can occur at temrperatures as low as 3 C -- i.e., inside a refrigerator -- and does not require strict anaerobic conditions... Home-canned foods are the most common sources, but commercially prepared foods have been implicated in about 10% of outbreaks. Vegetables, fish, fruits, and condiments are the most common vehicles... In recent years, noncanned foods (eg, foil-wrapped baked potatoes, chopped garlic in oil, patty melt sandwiches) have caused restaurant-associated outbreaks... C. botulinum spores are common in the environment...

Always take your food-safety info directly from reliable authoritative sources, not from rules-of-thumb quoted confidently and sincerely on online food fora!!

#63 Blether

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Posted 02 August 2011 - 09:44 AM

...

... Toxin production can occur at temperatures as low as 3 C -- i.e., inside a refrigerator -- ...


- slowly, as I understand it. I extracted my personal rule of thumb above from a long paper that described experimental results over time for different strains / substrates / temperatues.

Always take your food-safety info directly from reliable authoritative sources, not from rules-of-thumb quoted confidently and sincerely on online food fora!!


Amen.

Edited by Blether, 02 August 2011 - 09:45 AM.


#64 MaxH

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Posted 02 August 2011 - 10:59 AM

Blether, since you added the point about temperature, here's a little more on that complex subject incl. an aspect the health-science sources rarely address for home cooks.

Official advice quoted way upthread certainly favors refrigeration over unrefrigerated storage. (Purely from memory, in the lethal US case Roueché publicized, the spiced mushrooms, after long boiling in wine, were kept under oil for something like ten days in a cool household storage pantry. Incidentally Roueché didn't report the C. bot. spores' source in that case -- might equally have been the mushrooms themselves or one of the spices, such as peppercorns.)

The refrigeration picture is complex both because of multiple C. bot. strains (which the medical sources tell all about) and the variation in refrigerator temps. (which they don't). I've measured some of the latter directly, using the precision recording thermoms. that I use elsewhere with wine storage. Nominal target temp. for US refrigerators is 38F (3.3 C) (for still other reasons). But in practice (a) the target temp. varies somewhat between units and (b) more importantly, it cycles up and down, how much depending on thermal mass enclosed, construction, and especially, how much time the door stays open. I've observed temp. swings to about 60F (15.6 C), down to below freezing (which explained some wilting vegetables. :-(

So the official advice to refrigerate vulnerable foods for a few days and freeze for longer storage [more quoted upthread] isn't and really can't be more quantitatively specific.

#65 Kouign Aman

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Posted 02 August 2011 - 05:05 PM

I read the same book, as a result of which I always wash new jeans twice, never graft tomato plants to jimson weed rootstocks, and can't see the name Huckabee without thinking of hogs. :laugh:

I have GOT to get this book ! :D
"You dont know everything in the world! You just know how to read!" -an ah-hah! moment for 6-yr old Miss O.

#66 MaxH

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Posted 03 August 2011 - 09:19 AM

...I have GOT to get this book ! :D


A little more on Berton Roueché, then, for anyone so unlucky as to be unacquainted with his writing! Including info you won't see in standard online sources.

From about the 1950s through the 1980s, Roueché wrote a column in the New Yorker, "Annals of Medicine," reporting real-life cases of rare or tricky disease identifications, often solved by public-health doctors, that came to be called medical detective stories. Many involved foodborne illnesses.

Roueché's name was almost a US household word in his heyday: For literally decades, his original paperback anthologies Eleven Blue Men and The Incurable Wound, and a collection he edited of other medical writing (Curiosities of Medicine), were on every airport or supermarket books kiosk. Later, longer, anthologies included newer material and some, but not all, of the gripping stories in the famous original two books. You've seen some Roueché stories already (not always clearly credited), like the case of the "poison pants" that Arey alluded to earlier, if you've watched much of the celebrated US medical TV series House. (Credit Roueché for at least some of its success.) Possibly his best-known story, "Eleven blue men" (also the first anthology's title), has long been recommended to medical students (in a standard medical text I have) for its case study of a rare foodborne illness, accidental distribution of sodium nitrite mistaken for salt in a cafeteria. Nitrite depleted the victims' blood oxygen temporarily and they turned blue; contrast another of his cases, a man turning bright orange, with a similarly hard to trace but much more benign foodborne cause I won't spoil for you.

The cases are fascinating; Roueché's style is part of it. He was an incisive nonfiction narrator with scholarly attention to background. Thus his leprosy case (opening with a man reading a magazine, smoking a cigarette, and smelling something burning, only to find it was his own skin from the cig. and he hadn't felt it) goes into ancient and religious accounts of the disease, whose victims often were shunned. That is one of the memorable early stories absent from the large later anthology The Medical Detectives, which I have. The original two books (which I sold off for a few cents when graduating from college) becamse so rare and sought that they fetched upwards of $100 when I last checked. And some of their most memorable stories don't seem to've been reprinted much if at all, for whatever reason. Maybe medical obsolescence, or increased cultural sensitivity to certain details. The leprosy case ("A lonely road"), heroin addicts in Harlem carelessly cutting their drug ("A pinch of dust"), and specifically the botulism case I've cited in this thread ("Family reunion") all are missing from the large modern anthology The Medical Detectives.


#67 Kouign Aman

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Posted 03 August 2011 - 12:51 PM

Wow! Thank you. I will try to dig up a copy at below the current going price.

I wonder if he was involved in finding the cause of death for 3 hunters, found dead around their morning campfire?
Turns out they'd left the coffee pot out overnight, and in the am, first one up just heated up the leftovers, and all drank. All 4 died - the poisonous salamandar/newt that had crawled into the pot overnight, and the hunters that it poisoned inadvertently.
"You dont know everything in the world! You just know how to read!" -an ah-hah! moment for 6-yr old Miss O.

#68 loki

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Posted 18 August 2011 - 08:08 AM

And peach are not 'low acid'. They are in the 'acid' category. I don't think they've even been a problem. Who knows where these people get this stuff. I just heard on a newer PBS show that excluding oxygen is all you need to do to prevent spoilage, when it's actually the opposite for botulism. Must have taken a little information about keeping out O2 to prevent mold and such and basic human biology and come to an erroneous conclusion.

#69 Choumethemoney

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Posted 16 September 2013 - 11:03 AM

I am a retired microbiologist. Botulism comes from the soil and one ppm of the toxin is lethal. The reason you don't keep a raw plant (basil) immersed in oil even in the refrigerator is that botulism is an anaerobic bacterium. It goes without oxygen and in non acid conditions. Basil leaves and oil are a perfect place for this bacterium to grow.
You can make all the pesto you want and put it in the smaller baby food jars and freeze it. Even if present, the organism can't grow in the freezer. As you have read above, citric acid will acidify the product which has also been heated, so commercial products are safe, but not as tasty.
Remember no acid, no oxygen, is a definite no no, thus all the cautions involving canning green beans. Be safe and freeze your basil and smile all winter long.





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