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General Category => Yeast and Fermentation => Topic started by: beer_crafter on August 08, 2011, 02:23:37 PM

Title: Freezing wort-- am I risking botulism?
Post by: beer_crafter on August 08, 2011, 02:23:37 PM
Sometimes when I brew, I will save 1-2 quarts of my last runnings, boil them for 15 minutes, put into a tupperware, cool down, and then store in the freezer for making a starter at a later date.

After reading an article about canning wort, I am wondering if my process is opening the possibility of botulism.  Is this process safe?
Title: Re: Freezing wort-- am I risking botulism?
Post by: denny on August 08, 2011, 03:09:41 PM
To be safe, I think I'd boil it after freezing, before you use it.
Title: Re: Freezing wort-- am I risking botulism?
Post by: blatz on August 08, 2011, 03:10:36 PM
Sometimes when I brew, I will save 1-2 quarts of my last runnings, boil them for 15 minutes, put into a tupperware, cool down, and then store in the freezer for making a starter at a later date.

After reading an article about canning wort, I am wondering if my process is opening the possibility of botulism.  Is this process safe?

eh - I would do what I do to be safe instead: same process, except I just save the runnings, freeze them and then defrost and boil when needed for a starter.  yes its not as convenient as what you are doing, but it would be safer to can if you want to have ready made starter wort.
Title: Re: Freezing wort-- am I risking botulism?
Post by: beer_crafter on August 08, 2011, 03:21:26 PM
Right, so I do exactly that-- defrost, boil and then cool to make my starter.  So, the wort is boiled twice.  But I thought that it is the growth of botulism spores that produces the toxin, not the existence of live spores themselves?  In other words, I thought that boiling botulism-tainted food does not make it any less toxic.  I could be wrong. 
Title: Re: Freezing wort-- am I risking botulism?
Post by: a10t2 on August 08, 2011, 03:30:34 PM
Even without boiling the wort a second time, your procedure should be perfectly safe. Boiling won't totally kill off the spores, but it will certainly denature the toxin itself, if any is present to begin with. Once the yeast is pitched into the wort, the rapid reduction in pH will also significantly inhibit germination of the spores, and once the spored are ingested the pH of your digestive system is low enough to stop germination entirely. The wort would only be in the "danger zone" from the time it thaws until the yeast is pitched. As long as that doesn't extend over several days, there's very very little danger.
Title: Re: Freezing wort-- am I risking botulism?
Post by: hopfenundmalz on August 08, 2011, 04:02:45 PM
There was the great Botulism debate on the HBD in the 95-97 timeframe.

http://hbd.org/

Click on the seach function, do a Google domain search for "botulism".  Hope you have some time to spend reading that.
Title: Re: Freezing wort-- am I risking botulism?
Post by: beer_crafter on August 08, 2011, 04:05:17 PM
Great info, thanks y'all
Title: Re: Freezing wort-- am I risking botulism?
Post by: EHall on August 08, 2011, 04:19:14 PM
so if botulism is present when you pitch, would it survive thru the fermentation and development of alcohol?
Title: Re: Freezing wort-- am I risking botulism?
Post by: Jimmy K on August 08, 2011, 04:31:00 PM
Are we all missing something? Or am I? Freezing is a pretty foolproof food preservation method that is practiced by millions of people around the world EVERY DAY with little or absolutely no precaution taken to prevent botulism. There are no 'safe home freezing' classes at the local extension office, no books, nothing. Freezing won't neccessarily kill contaminating microorganisms, but it will stop them from growing.
Title: Re: Freezing wort-- am I risking botulism?
Post by: hopfenundmalz on August 08, 2011, 04:40:52 PM
Are we all missing something? Or am I? Freezing is a pretty foolproof food preservation method that is practiced by millions of people around the world EVERY DAY with little or absolutely no precaution taken to prevent botulism. There are no 'safe home freezing' classes at the local extension office, no books, nothing. Freezing won't neccessarily kill contaminating microorganisms, but it will stop them from growing.

I think the HBD thread was about canning the wort.
Title: Re: Freezing wort-- am I risking botulism?
Post by: tschmidlin on August 08, 2011, 07:03:42 PM
You don't even need to boil it, taking it above 140F should denature the toxin, and since you are freezing the wort for storage there is really nothing to worry about.
Title: Re: Freezing wort-- am I risking botulism?
Post by: 1vertical on August 09, 2011, 03:10:22 PM
Quote from: CSUextension
The majority of reported cases of botulism have traditionally been food-borne in nature. In recent years around 30 cases per year have been reported.
 

http://www.ext.colostate.edu/pubs/foodnut/09305.html  (http://www.ext.colostate.edu/pubs/foodnut/09305.html)

Not very many per capita....but you would not want to go through a poisoning by this agent.
Title: Re: Freezing wort-- am I risking botulism?
Post by: denny on August 09, 2011, 04:12:17 PM
so if botulism is present when you pitch, would it survive thru the fermentation and development of alcohol?

I'm not a microbiologist, but my memory of this discussion before tells me yes, it does.
Title: Re: Freezing wort-- am I risking botulism?
Post by: tschmidlin on August 09, 2011, 05:11:51 PM
There is a difference though, between survive and grow.  It might (or might not) survive as the pH drops over the course of fermentation, but it won't grow at beer pH.

Spores will survive freezing, but if you boil the wort before you use it then you have little to worry about from botulism.
Title: Re: Freezing wort-- am I risking botulism?
Post by: denny on August 09, 2011, 05:52:57 PM
Thanks, Dr. Tom!
Title: Re: Freezing wort-- am I risking botulism?
Post by: tschmidlin on August 10, 2011, 03:42:07 AM
Thanks, Dr. Tom!
Not yet :)

Paperwork first! ::)