[Free Rider]

This may be a stupid question, but I can't seem to find the answer anyway. Background... I want to start making my own jams.

1. In documents describing canning there are warnings all over the place about botulism. The bacteria are apparently on all fruits and vegetables (and other places too), but don't become toxic other than in an anaerobic (airless) environment. It is killed with heat, which is why canning uses high temperatures.

2. I bought a Foodsaver vacuum sealer to remove air from bags and cans, sealing the food in an airless environment. This is supposed to help the food keep longer.

3. One can also freeze food in airless environments (to prevent freezer burn) and I've used that Foodsaver vacuum sealer for that purpose too.

Now the question -- why the warnings about botulism in scenario 1, the canning thing, and not in the vacuum sealing or freezing instance? Should I be afraid of that food which has been kept in an anaerobic environment?

[Luc_H]

My answer here is: kinda yes.

First, Clostridium Botulinum is a spore making bacteria found everywhere but originates from the soil. The spores develop in warm, moist, low acid, anaerobic (without oxygen) environments where a lot of proteins are available (particularly meat). That type of environment is found under rotting animal carcasses. If any one of these conditions change, the bacteria reverts to making spores and waiting for the next opportunity. Obviously spores travel on air currents.

Knowing spores are killed at specific time-temperatures combinations, covering 2 conditions is considered safe. in Canning, the right temperature-time combo plus proper sealing covers 2 conditions, an additional factor would be an acid food (i.e. tomatoes) and lack of appreciable amount s of protein (also in the case of tomatoes).

Canning must be well controlled because cans are stored at room temperatures and are anaerobic (2 conditions uncontrollable).
Now you understand the increased danger potential of meaty spaghetti sauce in a can compared to tomatoes (proteins).
compared to chicken à la king or pâté: (proteins + low acid)

Vacuum sealing meat is problematic because: moist, high Proteins, low acid, no spore killing heat treatment. The only things working for you is storage temp.

Fortunately, botulism develops very very slowly and at near room temperature.

Safe practices are, if using sealed vacuum bags: Vacuum meat cold or frozen, freeze ASAP, thaw rapidly in cold water bath or in the fridge for no more then 24hrs, never leave meat to warm up to room temperature while still vacuumed packed.

Nitrite (nitrates) combined with erythorbate/ascorbate are the only additives that prevents botulism (and only botulism since this combo is not a generic antimicrobial). It prevents botulism from developing during the long curing processes sometimes at near room temperature.

Personally: I do not vacuum pack fresh meat, I don't buy pre-packaged cooked roast beef (no nitrates) and I only can at home acidic - low protein foods.

I am overly cautious that way.

Luc H.

[Free Rider]

Luc, I knew you would come to my rescue.

I'm not packing meat at all. Should I worry about the vegetables? Or only when I have cheeses and such that are higher protein environments?

I recently packed and froze prickly pear. I believe they have a protein-eating enzyme. I suppose it should be okay?

[siduri]

I don;t know about all the other conditions you describe (vacuum packing, etc) but want to put your mind at ease on jams. Jam is also somewhat acidic, and no protein, and it's boiled very well, so if you pack it into jars you just boiled for several minutes, you won;t get botulism. Same for pickles packed in vinegar (acid)
Other stuff, i would beware of, and they usually say you should process under pressure.

[Luc_H]

Free Rider,

I don't know what to advise about packing vegetables other then make sure you hit the temperature for the correct amount of time. most veggies are low acid but also low protein. Botulinum prefers a high ration of protein (particularly meat proteins but not exclusively).

Cheeses, particularly hard ones, by nature are acid and also prevent colonization by other bacteria because the resident lactic bacteria guard their turf like street gangs do very exclusively. Low danger there.

One product that is very dangerous is packing garlic in oil... I forgot to mention that. There are well founded warnings about this practice because
Anaerobic, no heat treatment, moist, low acid (protein is debatable) but the bulb comes from the soil hence has a high potential of carrying spores.


Luc H

[Luc_H]

Originally Posted by siduri

I don;t know about all the other conditions you describe (vacuum packing, etc) but want to put your mind at ease on jams. Jam is also somewhat acidic, and no protein, and it's boiled very well, so if you pack it into jars you just boiled for several minutes, you won;t get botulism. Same for pickles packed in vinegar (acid)
Other stuff, i would beware of, and they usually say you should process under pressure.

I got carried away and forgot to cover jam... ditto what Siduri said (plus sugar traps water preventing many bacteria from surviving).

Honey is problematic if it is not pasteurized it should not be given to children under 2. Honey are known to contain spores which are destroyed by stomach acids and prevented from sprouting in the gut because of our resident flora of gut microbes. Children under 2 lack one or both of these conditions.

Luc H.

[Free Rider]

Thanks, all.

Another question, related: Is C. Botulinum killed below 38 degrees F?

[Luc_H]

No.
(in general, bacteria never die at near or freezing temperatures.... in the real world some do but never all of them).
The spores are even better at surviving freezing temps.

Luc H

[Free Rider]

Eeek.

I suppose that means I should cook the prickly pear I froze rather than eating it raw or thawing it and making it into ice-cream?

[Luc_H]

Free Rider,

Hold on!!! Back up a little!!!!
How did you come to that conclusion?

I said that bacteria will not die that doesn't mean they will multiply while frozen! What I wanted to say is freezing does not in anyway kill bacteria in food (a misconception).
Bacteria propagation basically stops at 4C (38F) and lower. Regardless which bacteria is on the food at the time you freeze it, the population will be the same when you thaw it (think of cold/freeze has hibernation). It will not be more contaminated.
Thawing a piece of meat that is vacuum pack and leaving it in the fridge for an extended period of time (2-3 days) starts to get risky but leaving at room temperature them things can get nasty (not only on a botulism level but other microbes as well).

That said, if you thaw you prickly pears in the fridge then make ice cream with it, no problem. Even eating them is still no problem, any bacteria did not have a chance to develop while cold/freezing. Just don't break the cold zone... stay below 4C (38F) to prevent bacterial growth.

Luc H.

[Free Rider]

Hooray!!!!!!!!!

[Luc_H]

Luc wipes his brow... phewwww!

[KYHeirloomer]

Luc,

I think there's a lot of confusion on people's part as to the difference between microbial presence and microbial growth; and what that means in practical terms.

Maybe you could post a tuturial on that for the folks who don't quite understand.

[Luc_H]

Hi KYH,

Let me think about that...
Thanks for proposing....
Luc H

[Free Rider]

Hmm... now what about mincemeat? The recipe I use has no beef suet or anything. It's just fruit and sugar and alcohol. I assume that the sugar, citrus and alcohol inhibit the botulism as the mixture is kept at room temperature for three months before it's used.

After having read the botulism warnings, I began to wonder why I'm still alive.