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A little while ago, when making a starter for my blonde ale, I had yet another boil-over...

My procedure was pretty standard; add some DME and water to a 2000ml Erlenmeyer flask and boil on the stove for 15 minutes or so. I'd then cool the wort using an ice-water bath, pitch my yeast, get it going on my stir-plate, and clean up. Start to finish this would normally take 30 to 45 minutes. I don't know what I've been doing but, lately, I just can't seem to avoid boiling over. I end up making a complete mess of my stove and add an extra 15 minutes to clean everything up. I even started using foam control to lessen the chances of a boil-over but still seem to screw it up. (I think the problem may have something to do with keeping a steady temp on my electric glass-top range.)

At any rate, that last boil-over prompted me to pick up a pressure canner and a couple of cases of mason jars (about $9/case at my local ACE hardware). I had heard some mention of canning starter wort on The Brewing Network. It sounded like a great way to save some time and also avoid the dreaded boil-over. Another great resource I came across when searching the topic online was Drew Beechum's article, "The Starter Made Easy". [Edit: Forgot to mention Bugeater's forum post. Lot of good info there as well. Thanks Wayne!]

Last night I finally got some time to try it out. I probably could have saved time by filling a few jars with DME and water and just processing that one batch but I decided to go all-in. I ended up mashing 8 pounds of 2-row at 150°F and pulled off 7 gallons of 1.038 wort. This was enough to fill up all of my 12 half-gallon jars and another 4 quart-sized jars.

With my new Presto 23-Quart Pressure Canner ($79 shipped from Amazon), I was able to process 2 gallons of wort at a time (4 half-gallon jars). Even though they're only processed for 15 minutes at 15psi, each batch took a considerable amount of time...
  • boil 10 minutes to evacuate all air from canner
  • place regulator on vent to bring up to pressure. ~5 minutes.
  • process @ 15psi for 15 minutes
  • take off heat and allow to cool. This took about 45 minutes.

I had 4 batches to process because I had an extra 4 quarts more than I expected (mash efficiency was about 80%. Up from 75%.). That's about 5 hours just to can everything. The whole process including clean-up took me about 7 hours. I ended up with enough for 14 two-liter starters. (A good year of brewing for me.) If you figure 30 minutes to make a starter on the stove, it would add up to 420 minutes. 420 minutes = 7 hours!!! I guess I broke even... but no boil-over!! Plus, I'll be able to make a starter at the drop of a hat. Just pop the lid on one of my jars, dump into a sanitized flask, pitch the yeast and place on stir-plate. Nice!

Some info on pressure-canning:


When pressure canning low-acid foods such as wort, it is important to follow proper canning techniques. Jars must be processed for 15 minutes at 15psi (250°F).
Failure to do so may result in death!

The pressure-canning process is relatively simple but it's extremely important to follow it exactly. The problem is that wort is a low-acid food and the canning process removes all oxygen. What you're left with is a low-acid, anaerobic environment rich in nutrients... the perfect environment for the bacteria Clostridium botulinum to grow. As botulinum grows it creates nasty neurotoxins that can cause botulism. Spores of this bacteria can survive temps of up to 240°F. If you're not careful to keep your canner at the correct pressure for proper amount of time, you could end up with the botulinum toxins in your starter wort. Bad news!

"Botulinum toxin is the most acutely toxic substance known with a median lethal dose of about 1 ng/kg (1 part per trillion) (intravenously) meaning one teaspoon can kill 1.2 billion people."
(I'm quoting Wikipedia here so it must be true.)

Per DrYeast on The Brewing Network's forum:
"There's an easy way to tell if your food poisoning is botulism or not.
Quick onset, cramping, liquid out of both ends, want to die = not botulism.
Slow onset, paralysis and death = botulism."

NOTE: During the normal brewing process, the fact that botulinum spores may survive the boil isn't that big a deal. The spores cannot grow in an aerobic or acidic environment. As the yeast ferments the beer it may use up oxygen but it also increases alcohol and reduces the pH enough to inhibit the bacteria's growth. Again, it's the growth of the spores that create the toxins.

The Jars

The Rig

Filling Jar
Not so easy when taking a picture.

The Pressure-Canner
With 4 half-gallon jars.

Before and After Processing

Protein Break

Follow Up: Making a Starter from Canned Wort

Views: 2858

Comment by Craig Walter on July 23, 2009 at 9:57pm
You are way to good at this.

Comment by Jeff Louella on July 24, 2009 at 1:54pm
Did you boil the wort first before filling the jars, or pull it right from the Mash Tun?
Comment by Sam Scott on July 24, 2009 at 2:02pm
I collected all the wort in my boil kettle, however, I did not boil it. I stirred it to make sure there was no stratification of sugars and then filled the jars. Obviously, from the pictures, I ended up with a lot of break material after processing the jars. Not sure how this will affect the starter. When I go to use the canned wort, I'll try to leave most of the break behind while filling the starter flask.

Next time I might boil the wort in my kettle and let the break material settle out before filling the jars.
Comment by D Walter on July 25, 2009 at 5:49pm
so unless i am mistaken here you still need to boil the wort anyway correct??? are you thinking this wort wont boil over as easily as the dme right in flask method??? o and i love this idea by the way and Craig is right you are too good at this lol... see you soon
Comment by Sam Scott on July 25, 2009 at 7:57pm
Once canned they don't have to be boiled again. That is, when I make my next starter, all I have to do is take a (room temp) jar off the shelf, dump it into a sanitized flask and pitch the yeast. I can get a starter going in less than a minute or two.
Comment by D Walter on July 26, 2009 at 9:13pm
o ok i see thats a great idea that i will have to steal and make my own...
Comment by D Walter on July 26, 2009 at 9:15pm
o and if you put the wort in the jars hot wouldn't they pressurize themselves as they cool???
Comment by Sam Scott on July 27, 2009 at 1:00pm
Dan, your question makes me nervous... so, first a disclaimer: You MUST use a pressure-canner and procees the jars at 15psi for 15 minutes. This is the only way to ensure the wort reaches the temp (250°F) required to kill any botulinum spores that may be present (see warning above).

I'm just not sure what you mean by "pressurize themselves". The jars are sealed by a reduction in pressure in the head-space under the lid. That is, as the wort cools in the jar, a vacuum is created that sucks the lid on and seals the jar. If you put the lid on a jar filled with hot wort and let it cool, a vacuum may form and the jar may seal. However, if that hot wort didn't reach 250°F, you didn't kill everything. You'll end up with an anaerobic, low-acid, nutrient rich medium where any surviving botulinum spores will thrive.


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