Freezing, pressure canning and botulism...

All things preserving - canning, water bath (vacola), freezing, drying your harvest. We discuss all methods and the pros and cons, be nice to each other, please we all have our ways of preserving.
missy
Posts: 24
Joined: Mon Nov 02, 2009 7:34 pm

Freezing, pressure canning and botulism...

Postby missy » Mon Dec 21, 2009 8:59 pm

I have a mixed up and muddled up question to ask. See if you can figure out what I am asking ...

How come you have to pressure can beans & corn etc but it's ok to freeze them? From what I can gather, freezing doesn't kill the botulism spores. So is it just because they aren't in an anaerobic state in the freezer? Or is it because the freezing prevents the toxin from forming? I started wondering since I froze some basil leaves in ice blocks last week but realised that you would have to can basil. Can you put basil in say tomato sauces and water bath it? or would you have to pressure can it if you put basil in. What about garlic. I'm thinking you would pressure can... Can I leave my basil frozen or am I just asking for trouble there?

Thanks and congrats to the person who figures out how to answer this "question"... :D
Missy

minnie
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Joined: Sat Mar 15, 2008 9:23 am
Location: Alice, West of Casino, NSW
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Re: Freezing, pressure canning and botulism...

Postby minnie » Tue Dec 22, 2009 4:05 am

Hi Missy,

My understanding was always that botulism needed certain conditions to grow. I always give the example of my aunt and two cousins who got it from a can of corn (supermarket can) that had a tiny hole in the can, too small to allow anything to escape but enough to let in enough oxygen to give the right conditions.

Here's a couple of things I found with a google search - there's a lot of information about botulism, much of it from the US where there is a greater number of people getting it.

For botulism to occur there must be several conditions present. The spores must be present in a low-acid food, which means that the food is processed or stored in some way that removes the oxygen and not enough heat is applied to destroy the spores.
http://www.publichealthgreybruce.on.ca/ ... -borne.htm


In August and September 2001, several cases of botulism, a life-threatening illness caused by the bacteria Clostridium botulinum, were reported in the United States. Frozen, fully-cooked products were suspected of causing these illnesses.
http://www.fsis.usda.gov/Fact_Sheets/Fr ... _Botulism/


I thought the information on frozen foods very interesting, the full information is worth reading and defrosting and refreezing seemed an issue. Something I've always be told not to do, and I do know people that think it's okay and refreeze things like meat, I don't!

In Australia botulism is a reportable disease and some time back I looked up the numbers, from memory since about 1990 we've had the odd year with one case, there was one case of infantile botulism (different from food borne, it's from honey with babies under 12 months), there was a year with three (I figured same family, like my aunt and her boys in the 70s) and otherwise most year none. For a population of approx 22 million it's not many. But it doesn't mean it doesn't happen and it also isn't just about home preserved as many cases of food poisoning generally come from commercially processed products.

With your basil, I think it would be fine. I put basil in my pasta sauce that I hot water bath, I don't put garlic into it until I'm using it then I mix in garlic. I do put garlic in salsa though as it has vinegar in it so it up's the acidity. The big no no is garlic in oil. I like to keep some things a bit generic and add later with what I feel like at the time of cooking.

I hope this helps?
:D
Vicki

Mojojo
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Joined: Sun Nov 09, 2008 8:01 pm
Location: Perth and Donnybrook, WA

Re: Freezing, pressure canning and botulism...

Postby Mojojo » Sat Dec 26, 2009 12:36 am

Doesn't C. Botulinum need an oxygen-free environment to grow? I think the holes in the can thing might be letting off the gas they produce, or allowing dirt and dust (containing bacteria) in that is the issue - not the oxygen.

That why botulinum loves low acid bottled (BWB) food - no air, sits in the pantry at the perfect temperature for a bacteria party.

On the freezing corn and beans:
Its not the actual bacteria that make you sick - its the toxins they produce when they are active - multiplying away that its the problem.
The spores are only active between 3 to 4 celsius and 50-ish celsius.
You are right missy they are not killed by freezing, but are inactive, not toxin producing. (if, like Vicki's link said, they are there in the first place) Defrost and cook without delay - for all foods.


Definately defrosting then re-freezing is not good at all... and yes, people do it and might not get sick, but it certainly increases the likelihood. Inactive spores of any variety of bacteria get the chance to happily multiply and start making toxins, then popped back in the freezer for a sleep again so when they are defrosted again the party just starts again, only bigger this time. Its also why defrosting in the fridge is a good idea, as then it is never sitting around in the temperature danger zone (4 - 70 celsius) - especially with large items where the outside may be fully defrosted and at room temperature and the inside stil frozen.

Also a good point is the danger zone in temp when cooling cooked foods before freezing them. I still remember the motto from my cheffing days - four hours at four degrees no deeper than four inches, then into the freezer. NEVER left to cool at room temp if they were going to be frozen. I've sadly thrown out a giant batch of spag that was meant to go in the freezer and got forgotten about and not found til the next day. Just not worth chancing it.

I freeze basil in ice cube trays (and as pesto) every summer. Actually, now you mention it, need doing now as mine is all going to flower. :)
~ Jo
_________________
Two roads diverged in a wood and I -
I took the one less travelled by,
And that has made all the difference.
~ Robert Frost

minnie
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Joined: Sat Mar 15, 2008 9:23 am
Location: Alice, West of Casino, NSW
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Re: Freezing, pressure canning and botulism...

Postby minnie » Sat Dec 26, 2009 6:49 am

Hi Jo,

I think the holes in the can thing might be letting off the gas they produce, or allowing dirt and dust (containing bacteria) in that is the issue - not the oxygen.


Yes I'd say you're right - holes let the bacteria in and then so small sealed with the corn, or I'm assuming. I was quite young I think it was the late 60s and only know the three collapsed and were rushed to hospital and only just made it. It was said luckily the youngest and my Aunt's mother didn't like corn. I'm always funny about dented cans or old looking since.

While we have much more salmonella and EColi (also kill) in Australia, often the one feared the most Botulism is extremely rare. Whether this is because we don't have a lot here I don't know, certainly don't have all the answers but I'm the only person I've ever met that does know personally someone who had it.

The poultry farm in Tasmania that kept getting eggs with salmonella was interesting... now eggs is something people are funny about, like washing the dirt off them, that's one not to do!

I waffle ;) ... have a good boxing day everyone.
:D
Vicki

missy
Posts: 24
Joined: Mon Nov 02, 2009 7:34 pm

Re: Freezing, pressure canning and botulism...

Postby missy » Sat Dec 26, 2009 3:49 pm

Thanks everyone.

I picked some beans the other day, blanched them and stuck them straight in the freezer. They look wonderful and green and still crispy, although I hope they stay that way when they are cooked. I hate soggy beans...

Now about that pesto... can you can it? Well you must be able to, otherwise how is it that you can purchase jars of pesto??? I foolishly discouraged my DH from buying the really big sized freezer a few years back and since we buy bulk meat, bread and milk (although I sure hope we are going to stop having to do that soon) I can't fill it up with too many things over the year. I was hoping to get around this problem by canning more things.


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