Canned Starter Wort

I’ll be the first to say that the method outlined below for making canned starter wort is most likely excessive. The canning process most likely kills off any microbes or organisms that would cause problems with the wort, so much of the sanitation and care I put into making starter wort is unnecessary and just adds time. That said, I have never had a problem with any of my starter wort, and I’ve never had an ounce of hesitation about using some of it. I’ve also never had any of my mason jars show signs of botulism or problems, so I think I will stick with this process. If you are reading it, I’m assuming it is because you are interested or looking for a procedure – mine is certainly a starting point.

My process takes somewhere between 8 and 11 hours. It could easily be shortened by a few hours by starting from DME, however since I brew all-grain, making all-grain starter wort doesn’t bother me in the least – and since I have complete control over the mash conditions, I can make a much more consistent and fermentable wort than you can with DME. So with that, here is my procedure:

Step 1: Brew starter wort

Starter wort all-grain setupI brew 5 gallons of starter wort at a time. My equipment is optimally sized for 10 gallon batches, but 5 gallon batches (of even low gravity) does not represent a problem. I typically mash for 60 minutes at 147-149 degrees, and the mash typically drops down to about 145 during the saccharification rest. This range produces a highly fermentable wort, which is desireable for making starters and propogating yeast. I take all the care and precautions I do with an actual batch of beer, trying to leave as much solid material (grains bits, husks) in the mash tun and as much break in the kettle as possible. The recipe is 100% brewers 2-row malt, and I throw in enough hops to bring the IBUs up to the 5-10 range – which typically only means 1/4 to 1/2 an ounce at sixty minutes. For starter wort recipes I recommend pellet hops as they settle better and come with fewer issues than whole hops can.

Step 2: Sanitize the mason jars

Sanitizing mason jarsStarter wort does not go into glass carboys for fermenting, but instead goes into 24 tiny little jars. I use quart mason jars, and do take the time to scrub, rinse and sanitize all 24 jars prior to draining the wort into them. Some may say this is unnecessary since pressure canning will essentially autoclave your wort and jars, however I still take the time to do this step. The jars are filled complete and soaked for 20-30 minutes, and I sanitize the lids as well. As I pour the sanitizer back into the bucket, I put a sanitized lid ontop of the jar and lightly screw on the ring – just holding it in place. The lid stays on the jar until I drain the wort from the kettle. While the starter wort is cooling and settling is an excellent time for this activity.

Step 3: Fill the mason jars

Once you’ve brewed your starter wort and chilled it down to 70 degrees, its time to put the wort in jars. Make sure the break is well settled out – you don’t want to fill your mason jars with a bunch of break material as well. I sometimes drain the kettle into a sanitized carboy and let it settle for a few hours, and then rack the beer into the mason jars instead of filling directly from the kettle – this may be a necessary step if you are a pump / counterflow chiller brewer.

Hose and NozzleTo fill the mason jars, I use a length of sanitized 1/2″ reinforced vinyl tubing with a nozzle stuck on the end. The nozzle is actually just the inner part of an airlock that broke on me – but it fits the 1/2″ tubing perfectly and works great for filling jars. The nozzle is obviously not essential, but I find it does a much better job directing the flow than just the hose does, which helps minimize spillage during transfers from one mason jar to the next.

 I unscrew the ring and lid from the sanitized jars one at a time, and leave the tops off only as long as it takes to fill each jar. I do not close the valve on the kettle as doing so may disrupt the break settled below the valve, but instead have another jar ready for filling right next to the one that currently is – this means only 2 jars ever have the lid off at any given time, and not for more than 30 seconds while a jar fills. As soon as one jar fills, I transfer the tube & nozzle to the next empty, and quickly screw on the lid and ring (not even finger tight). This process is repeated until the kettle is empty, or a whole bunch of break material gets into the kettle.

Step 4: Prepare the pressure canner

This is a step that will vary depending on your equipment. I have a large 21.5qt pressure canner with a metal-to-metal seal that can hold 7 qt jars at a time (All-American, Model 921), which works out to 3 or 4 canning cycles to get all 5 gallons of starter wort.

The very first thing I do is inspect the canner for problems, per the manual. This means checking for pitting problems, checking the pressure relief plug, making sure the vent pipe is clear, and the pressure gauge is functional. This past inspection I noticed that the gauge doesn’t zero completely anymore, and measures 2 PSI at atmospheric pressure. It seems that the 15psi reading is accurate (based on my past experience), however I will check into what it takes to get this recalibrated.

The metal-to-metal seal on my canner requires a very thin coat of vaseline or petroleum jelly on the inside lip of the lid and the inside bevel of the canner to seal properly. One coating seems to last through about 4 cycles just fine – but since I only can starter wort 1 or 2 times a year (it lasts me a long time), it may last longer than that.

Preparing to canOnce the canner is lubed up, I put in a support tray for the mason jars to sit on (so they are not in direct contact with the bottom of the canner). I then put in 7 mason jars, checking to make sure the rings are screwed on tight, but not to tight. My general rule of thumb is to twist them until I start feeling a moderate amount of resistance. They should not be screwed on tightly as that can cause the jars to explode (!!) during the processing.

I then fill the canner with about 1 gallon of hot water, which fills up to a little below the neck of the mason jar. You don’t want the cans totally immersed, but you do want enough water where you don’t worry about it all boiling off during the processing. 1 gallon seems to be perfect for 3 canning cycles (21 jars) in my canner.

It is then time to put on the lid and process the wort. I typically put the canner lid on and lock it into place, then check to make sure the space between lid and canner is equal all the way around. Then I swing my lock nuts up and tighten them 2 at a time (on opposite sides of the canner). Before tightening down significantly, I do a second check on the spacing, then tighten finger tight (I don’t really crank down on them at all… its unnecessary and can really stick the lid on). Once things are all tighted up, its time to fire up the burner.

Step 5: Execute a canning cycle

This is the most important (and nerve-wracking) part of the entire process. It is probably just my safety training and exposure at work that makes me so nervous, but I look at the pressure canner as a 21.5qt pressure bomb, ready to explode and take out everything around it. Its somewhat irrational, since the pressure cooker has a built-in pressure relief plug that will blow at 18 PSI, but things can (and often do) go wrong. Another reason for the paranoia stems from my method of heating the pressure canner; My gas range doesn’t crank out nearly enough BTUs to be effective. The first time I canned starter wort, I did it on the stove and it took 2 hours for the canner to heated up to pressure… Which is nuts. The second time I adopted my current method which involves a Camp Chef 80K BTU propane burner I use for brewing – which has more than enough power to get the canner up to temperature and pressure in a hurry, and it is balancing the power with safety that I spend most of my time worring about when canning, and it will be heavily reflected in the following description.

Above all else, the inviolable rule I follow is to NEVER WALK AWAY while the propane burner is on and the canner is pressurized. Period. I’ll run and grab a drink or heed the call of nature while its heating to a boil, but once it is pressurizing I do not leave for anything.

  • The pressure canner sits on the propane burner before I load it with water and mason jars. It probably could be moved even full, but I try not to. The pressure weight is left OFF
  • I turn on the burner and keep the flame low and constant… to where they don’t lick up around the sides of the pressure canner, but there is a steady blue flame underneath. This allows the burner to come to a boil in around 10-15 minutes, which is absolutely as fast as I want it to (sometimes I dawdle and let it take 20).
  • I listen closely for sounds of boiling and for evidence of steam coming out the vent pipe. As soon as the boiling begins, I turn the propane burner way down so it maintains a boil, but is not so vigorous that the mason jars are knocking together inside. A steady stream of steam should escape the canner for 7 minutes before placing the weight on. This process is called “venting”, and it removes air in the canner and replaces it with steam – which supposedly helps prevent oxidation of whatever you’re canning. The steam should not escape so fast that it whistles, and you definitely should not see the pressure inside the canner rising – either of those indicate you should probably reduce the heat / propane being applied.
  • I place the weight on the vent pipe with the number “15” facing down, indicating 15 pounds of pressure. This allows the steam to slowly build up inside the canner, building the pressure and temperature to 15 PSI and 250 deg F. It should take 10-15 minutes for the pressure cooker to reach 15 PSI, and you must keep a constant watch on it to ensure everything seems normal. Again, there will be some movement of the pressure canner due to boiling, but you should not hear the mason jars knocking around inside too vigorously
  • As the pressure canner pressurizes, you may notice some steam accumulating around the vent pipe and perhaps a little escaping from the overpressure plug. This is normal… the overpressure plug will seal itself once the pressure builds some.
  • Once the target pressure of 15PSI is reached, start the timer for 25 minutes. Also crank back on the propane as far as you can without killing the flame. It takes VERY little to keep 15 PSI, and too much will run the risk of overpressurizing the canner. One thing I have found helpful is to choke the burner’s air intake pipe by rotating it fairly closed – this decreases the air mixture and makes the propane burn less efficiently, but it also keeps it from from burning so hot (and sometimes from blowing out when a breeze comes along).
  • The weight on the vent pipe will rattle fairly frequently… you want to shoot for a couple seconds of rattling followed by 15-20 seconds of quiet, but I find it very difficult to achieve on a propane burner. I more try to make sure that it gets 5 to 10 seconds of quiet every 30 seconds or so, and I keep a very close watch on the pressure.
  • A continuous rattle for more than a minute is bad news, and you need to crank back on the propane or kill the burner for 30 seconds or so. The continuous application of heat is not the critial aspect (unlike maintaining a rolling boil in brewing)… here you are just trying to maintain the pressure, so if you must cycle your burner on and off to maintain a pressure of 15 PSI, then that is OK too.

Step 6: Slow cool down to regular boiling

Cool down to boiling. There’s something you don’t hear everyday. This step is easy. After the 25 minutes at 15 PSI, kill the burner. Come back in about 20-30 minutes after the canner has naturally come back down to a pressure of 0 PSI and 212 degrees. You should be able to tell its ready by knocking the vent pipe weight a little – if it hisses and steam escapes, leave it alone for another 5 minutes. Repeat until the hissing stops.

You do not want to try to make it cool down faster. Throwing water on the canner could cause thermal stress and permanently damage it. Pulling the vent weight off causes the pressure to escape quickly, resulting in superheated water and wort errupting all over the place. Just leave it alone.

Once the canner is cooled down, you also don’t want to wait too long before removing the weight. In theory, a vacuum could form in the canner and cause the canner lid to suck down into the main canner shell – which would make step 7 a royal PITA. I haven’t ever had that happen, but its one of the warnings in the canner book.

Step 7: Canned Wort Extraction

Once the pressure canner is back to atmospheric pressure and normal boiling temperatures, its time to remove the lid. I unscrew all of the bolts (in pairs on opposite sides, just like tightening). I then carefully do a quick check to see if the lid will just come off – which it never does. Every time I’ve ever pressure canned, I’ve needed to use a screwdriver to very carefully pry up the lid. This must be done carefully and gently as my canner is made of aluminum, and could potentially be scratched or bent by the (harder) steel screwdrivers. It shouldn’t take significant prying… just a light bit of leverage on one side, followed by a little more on the opposite… and maybe a 3rd or 4th prying at the 3 and 9 o’clock positions if necessary. Again – this should not require alot of force.

Canned wort - cooled and ready for useOnce the lid is off, I set it carefully on a towel or something to prevent it from getting scratched, and use the canning tool to remove the extremely hot cans of wort. I typically set the cans on the concrete floor of the garage. They’ll look a little gnarley – the canning process will cause more break material to form, and since they are so hot they will have a significant haze – but all the big stuff will fall out after 2-3 days at room temperature. After about 1-2 weeks sitting at room or cellar temperature, the jars should be completely clear with all the break settled on the bottom. Careful decanting will leave most of that break in the jar when you go to use the wort in a starter.

Once all the mason jars are out of the canner, wear some gloves and screw the lids on finger tight. Don’t crank down on them – but make sure they’re sealed. After about 10 minutes, the tops should suck down and become completely sealed to the mason jars. If you hit the tops with screwdriver, you should be rewarded with a high-pitched “ping” – if it has a low pitched thud, then it hasn’t sealed and you’ll need to try again (or use it ASAP). The jars themselves should cool down to a temperature you can handle in about 2-3 hours.

Once the tops are all screwed on, load in your second batch of 7 and start from step 4 again. I do not re-apply the vaseline with every cycle… just the first one, and that one coat should carry thru all 3 or 4 cycles without problem. More important than anything is to make sure that your lid space is equal all the way around, and you don’t rush the heat-up or cool down.

Hope this helps, and good luck!

    1. lhd7osc
      June 20, 2014 at 8:08 am

      Two questions: Do you leave them at ‘cellar’ temperature when storing? And how long do you think they’ll store?

      • brewznet
        June 21, 2014 at 6:43 am

        Yes, I store them in my basement at “cellar” temperature after processing them with the pressure canner. As far as how long they will store – I am not sure. I typically use all 5 gallons (24 jars) in a matter of 6 months, and have seen no issues over that timespan. As a low acid “food” product, I imagine it follows the same guidelines as any other, but you are probably fine up to a year (or perhaps more).

    1. May 26, 2009 at 7:54 pm
    2. February 11, 2012 at 5:40 am
    3. March 8, 2012 at 9:43 am

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