Purging Vessels with CO2

One of the bugaboos of my brewing has been oxidation, a papery flavor that develops after the beer has been packaged.  Oxidation alters the flavor of the beer over time, reducing its shelf life, but in extreme cases it can start adversely affecting the beer very quickly.  I’m not talking about hot-side oxidation, that’s been debunked as a factor in beer flavor.  I’m talking about any introduction of oxygen into the beer after yeast has been pitched.

Oxygen is vital to fermentation, at least initially.  I’ve read of some experiments in low-oxygen fermentation but I’m not quite ready to throw out years of brewing experience based on a few experimental runs using various oils as the source of sterols for yeast cell walls.  The problems occur if oxygen is introduced after fermentation is underway.  The compound responsible for the papery flavors can be detected at concentrations less than a part per billion so only a little can adversely affect beer.

As I write, I’m sipping a beer brewed October 4th of last year.  It’s April 18th:  The beer is six months old.  I can detect few signs of aging in it.  About the time of this brew, I got a CO2 tank and began sparging the vessels before transferring beer into them.  In fact, the beer tastes as good as when I bottled it.  By layering a bit of CO2 in the carboys before racking, I limited the amount of oxygen introduced to the finished beer.  It worked, as near as I can tell.  My beers no longer show signs of oxidations, not this nor any of the subsequent brews.

If you can’t afford to go out and buy a carbon dioxide tank and regulator, you can still get some benefits by limiting handling of the finished beer.  If you can avoid racking the beer, you eliminate one possibility to introduce oxygen.  If you have access to another inert gas and can sparge with it, that will work as well.  At least limt flow from the racking cane until the tube is below the level of the beer to limit splashing.  Bottom line, keep oxygen out of your beer.  It will taste better longer.

Kettle Souring

I got the tip on how to do this from Tim at the Dry Dock Brewery.  He’d given us a taste of his “Regal Tang” so I asked where the pineapple and mango flavors came from.  Turns out he’d used yoghurt to pitch lacto into hot wort, left it overnight, then boiled with hops the next day.

So I tried a batch.  I mashed, ran off the wort, boiled it for ten minutes, stuck a thermometer probe into it and cooled it to 120 degrees.  At 120 degrees, I pitched a couple teaspoons of my sourdough starter into it, insulated the heck out of it (as best I could), then left it overnight.  The next morning I checked the pH.  It was about 4.1, I wanted in the vicinity of 3.5.  I let it set a couple of hours then checked again.  4.0.  So I turned my hot plate on low.  The wort began to warm very slowly.  Seeing that it wasn’t about to get away from me, or so I thought, I went upstairs to take a shower.  When I came back to the wort, the pH was 3.9, okay, but the temperature was 151 degrees.  I’d killed my lacto.  So I boiled, fermented and still got a pretty good beer out of it, not as tart as I’d like but still nice.  Unfortunately, I didn’t take pictures.

New procedure involves my Inkbird temperature controller.  It controls both heating and cooling.  I generally use it to control my fermentation chamber – it’s holding the temperature above room temp for my 90-degree Belgian Saison.  Next batch I run my hot plate through it controlled to 120 degrees (50 celsius) with the probe in the wort.  The controller in Celsius mode holds the temperature to +/- 0.3 degrees, effectively 1 degree Fahrenheit, and the temperature is adjustable to 0.1 degree Celsius.  Interesting because the actual conversion of 120 degrees F is 48.9 degrees C.

So why kettle sour when there are other alternatives such as sour mashing, Brett fermentation, wild yeast, sour blends.  The literature will tell you, at least the snobbish parts, that kettle souring lacks “complexity” compared to other souring methods.  Here are my reasons for kettle souring above the others:

1.  It’s very controllable.  Some other methods give you what you get.  Souring in the kettle leaves you in control – you can stop the process at whatever level of tartness you want for the effect you want.  I’m even thinking of a very short kettle souring for my next batch of Irish Stout, since Guinness is rumored to use stale (read old), slightly soured beer in their blending process.

2.  You don’t contaminate equipment.  You boil the kettle after souring, killing off all the lacto before it can infect your next batch.

3.  It’s fast.  No waiting for a year or so for your Brett or your Lacto pitch to sour the beer.

4.  You can even control what you pitch.  Yoghurt works, sourdough starter works, natural sauerkraut would work, even pitching grains would provide lacto.

5.  Less chance of the enteric bacterial stench.  No need to stink up your work area.

6.  Most important, I like the results.

Brew Day – Dry Dock Naked Porter

Happy New Year to all!

My local craft brewery, the Dry Dock in Aurora, CO, brews a Vanilla Porter.  And I can’t stand it.  But when they leave the vanilla out, what a beer!  More to come, but first, a few other items.

Just finished Book 4 of the Brewing Elements series, Malt.  It was well written, a statement that pretty much ensures that the following review is not positive.  There was some useful information in there if you’re malting your own grain but for general homebrewing, not a lot.  You can learn how to calculate beer color from the book but Palmer already has told us how in “How to Brew” (the one brewing book that, if you don’t own, go buy, right now).  You can get a good idea of how to malt, a lot of info about the commercial production, shipping, storage and handling of malt and a good bit on some smaller craft malt houses but all in all, borrow it if you can, skip it if you can’t, unless you’re just fascinated by malt.  This book will not help you brew better beer at homebrew scale.

Now to brew day.  The Porter is very dark, 40 SRM.  It has lots of roasty-toasty flavor, in fact, I’d classify it more a robust porter than a brown porter.  I’m brewing it to 4.8 ABV, very sessionable.  It’s low-hop, 20 IBUs:  Malt is the key player in this beer.  It has some complexity, malt-sweetness to balance out the other flavors and I’m hoping my brew will get close to it.

Everything went well.  Really.  There was nothing to complain about.  I even enjoy a good Denver brew day in the snow….


I hit all my numbers and determined my new boil rate for the new, wind-shielded burner.  In the past, I’ve had to turn the flame up much higher to keep the wind that seems to blow here every time I start a boil from blowing the flame aside and stopping the boil.  So I got this shielded number.  Using my stick gauge, I was able to determine this bad boy was boiling off about a gallon an hour, less than my previous setup.  So I am now able to start with 7.25 gallons of wort to get to 5.5 by boil end rather than the 7.75 I used to start with.  Fewer boil overs, less mess.

Another new piece of equipment:  While cleaning up last brew day, I wasted yet another hydrometer.  I use a refractometer on brew day so I can take multiple readings easily but for the “real” measurement, it’s the good old fashioned triple-scale hydrometer.  The only problem:  The “cheap” hydrometers at the homebrew shop may not be well calibrated so it pays to check:


I filled the sample jar with distilled water, cooled it below 60 degrees F, the calibration temperature of the hydrometer, then let the water warm up.  Once it hit 60 degrees, I checked the reading, 0.998, or an adjustment of -.002 degrees.  So I now have to subtract 2 points from every reading I take with the new hydrometer.

If you haven’t calibrated yours, I’d do so.  Cheers!

Kottbusser Recipe

Having seen a search request land here, here’s my Kottbusser recipe.  It’s currently scaled for 10 gallons for brewing on the Ruby Street Brewing 10 gallon rig.

Yesterday’s experiment told me that next time I’ll sour mash the brew.  To do that, make your wort as usual but chill down to 120 degrees.  Pitch lactobacillus in one of two ways, either as a culture you bought or through throwing a few grains of malt into the warm wort.  Keep air away from the wort to avoid culturing acetobacter – you’ll get a vinegary taste if you do.  To keep air away, either cover the wort with plastic wrap and by that, I mean floating the plastic on the wort, or use a blanket of carbon dioxide to keep oxygen away from the wort’s surface.  In 12-24 hours, take a sample and if it’s tart enough, boil and add your hops.  Caution:  Don’t let anything you can’t sterilize fairly harshly come in contact with the soured wort.  Lactobacillus can be hard to get rid of once you have it.  I keep a separate setup of buckets, racking canes and so forth for anything soured.  I sour the mash in my kettle since it will be boiled and everything else is very clearly marked.  Duct tape is good for this.

Chances are the original beer was soured after the boil.  Lactobacillus Delbruckii is sensitive to hop oils so it won’t work quickly as a culture once the beer is hopped.  Lactobacillus Brevis is not but it will require very careful handling – it’s a very aggressive spoilage bacterium!  To sour in storage, again, cool the wort to 120 degrees.  Innoculate the wort and let it cool slowly for a few hours to let your lacto get going, then finish cooling and pitch brewer’s yeast.  Let the beer ferment, then bottle or keg as usual.  The beer will sour slowly, taking up to three months to develop tartness.

Hat tip to Ron Pattinson for tips on the recipe and techniques used to develop this recipe.

Brew in a Bag

Sunday night John Brindle gave a great talk on the Brew in a Bag technique at the Aurora City Brew Club (AC/BC) meeting.  Brew in a Bag, really mash in a bag, involves the use of a mesh bag to contain your grains during mashing.  Lautering then involves raising the bag up out of the wort and letting the bag drain.  The original technique was no-sparge but now a “teabag” sparge is used to get conversion rates near or in some cases even above what you can get with a picnic cooler mash/lauter tun.

I’ve used BIAB for some of my small batches but in the conversation after the talk, we arrived at another great use:  Developing recipes.  Since I was in Poland this year, I have wanted to brew a Baltic Porter.  It’s a really big beer, 8 to 8.5% ABV.  It also provides a chance of making nineteen liters of very expensive swamp water, so I intend to use BIAB for very small batches (one gallon) to dial it in before scaling up.  More great uses of the technique are testing malts, SMASH (Single Malt and Single Hop) batches or any other brew where you may not want 50 bottles of whatever it is you could be brewing.

BIAB requires minimal equipment above extract batches.  The technique is described very well in many places on line so I won’t go into it here.  Another advantage is a shorter brew day – I can turn out a batch in an evening as opposed to six to eight hours for my larger brews.  It’s a weapon in the homebrewer’s arsenal, to be used when it’s appropriate.  And I can testify to the quality of beers produced.  John’s are excellent.