Repurposing and Conserving CO2 During Kegging

With the current recommendations and restrictions on leaving the house, I’m trying to conserve basic brewing necessities as much as possible. This includes propane and CO2–neither of which can be ordered online (and really don’t count as necessities in the same way that groceries do, so it’s hard to justify many extra trips out to get more).

Keg purging is one brewing task that’s non-essential but nice, in terms of long-term beer quality. By keg purging, I mean replacing the ambient atmosphere in a keg (the stuff we breathe) with CO2 from a tank, to greatly reduce oxygen concentrations and postpone noticeable oxidation in the beer. My usual procedure prior to kegging is to fill a keg with StarSan, and push it out using CO2 from my CO2 tank. This doesn’t use a ton of CO2, but it still does use some up that could go to other purposes.

The easiest CO2-conserving scenario is to go without a keg purge, which is my normal procedure anyhow for many “non-delicate” beers (e.g., porters and stouts). However, I’ve noted that lighter lagers, pilsners, and blonde ales do show noticeable oxidation effects within a month or two without a keg purge. In the “good old days” of sharing growlers and homebrew happy hours and such, I could finish a keg in 4 weeks or so. Now, I expect many kegs will stay on service longer, and so I want to extend the quality as much as I can. Keg purging is nice, if possible!

One option I’ve considered is to use sugar-based carbonation (wort-driven krausening or corn sugar), which should both eat up any latent oxygen and carbonate simultaneously. I’ll likely try that for some future beers (especially more robust, darker styles), but I worry about oxidation risk from adding the sugar and also leaving the beer at slightly higher temperatures to allow the yeast to carbonate more quickly. It’s not an ideal option for light lagers.

So, how might I purge kegs to avoid oxidation and simultaneously conserve precious CO2 from my tanks? Reuse CO2 from empty kegs!

When a keg in the keezer is drained of beer, it’s full of CO2 at serving pressure. Normally, I just bleed this off before cleaning the keg. Why not repurpose the gas?

So, I hooked up a jumper between the gas ports of the empty keg and a StarSan-filled keg (the latter being the one I’ll fill with fresh, uncarbonated beer). Before doing this, I let the empty keg warm up, to give a bit more gas volume (yay, physics). I put a picnic tap on the StarSan-filled keg, hooked up the gas, and let the empty keg push out the StarSan.

It worked like a charm! The transfer took around 10 minutes, but the whole keg got drained, with a bit of residual CO2 left over. No CO2 went to waste, and I ended up with a purged keg ready to fill with pilsner!

The keg setup for CO2 purge. The keg at lower right is empty and just moved out of the keezer. The keg at upper left is empty and filled with StarSan. The red line is pushing CO2, and the clearish-white line is moving the StarSan into a sanitation tub (for use sanitizing equipment).
The colored lines and arrows here show the path of the gas and liquid. The yellow arrows indicate the flow of CO2, and the red arrows indicate flow of the StarSan.

Brew Updates: Palaeotis Pils 1.2 & Old Pine Pale Ale

I’ve kegged two of my brews in the past week, incluing my German pils and my American pale ale. Here are the details!

  • After 10 days in primary, I kegged Old Pine Pale Ale on 12 December 2017. I added the dry hops at this point, in a bag. Depending on how it works out, I may or may not remove the hops. I force carbonated the keg, and had it on tap by 16 December. The brew is pretty hazy at this point, and should clear up with time. Final gravity was 1.012, down from 1.052, working out to 5.2% abv.
  • My latest iteration of Palaeotis Pils started fermentation on 20 November 2017. It fermented at 50° until 27 November, when I raised the temperature to 54°. I raised the temperature to 66° on 2 December 2017, and cold crashed it on 10 December 2017. I kegged the beer on 16 December 2017. Final gravity was 1.010; with a starting gravity of 1.049, we’re clocking in at 5.1% abv. There is a touch of haze, which I’m going to settle out with time and cold.

Kegging Updates: Raspberry Belgian, Thumbspike Saison 2.1

I’ve done a decent bit of kegging this past week, to square away some beers slated for the Lake Arrowhead Brewfest that I’ll be serving with Horse Thief Brewers. The festival is just under a month away, but with a new baby soon to arrive in the household I know that time will be tight. Gotta keg while the kegging’s good!

Raspberry Belgian, transferring to the keg

Raspberry Belgian 1.1, transferring to the keg

My cold storage space is also tight, so I’ve decided to get the beers carbonated and conditioned using a more “traditional” keg priming technique. Not only does it cut down on my CO2 usage, but it also should help to eat up any residual oxygen from the transfer and help the beers stay a bit fresher. Now of course it would be ideal to do the full keg purge with CO2 and closed transfer thing. But as I said…I’m tight for time and not keen on always blowing through my CO2 supply. I also feel that these two beers should hold up pretty well (both are fairly high alcohol and one is quite tart); if it was a delicate lager, crystal malt heavy porter, or hoppy IPA, I would definitely do things differently.

In any case, here are the details on everything.

Thumbspike Saison 2.1

I brewed this beer on June 25, and fermented it at the ambient temperature–around 75° on up. I kegged the batch on 12 July 2017, with 2.75 oz. of corn sugar boiled in 1 cup of water. Around 5 gallons went into the keg. Final gravity was 1.003, down from 1.055. This works out to around 6.8% abv.

Raspberry Belgian 1.1

I brewed this beer on 27 June, fermenting it at around 66°. On the fourth day of fermentation, 1 July 2017, I added around 1L (~4.25 cups) of Vintner’s Harvest raspberry puree. After about a week, I moved it out of the fermentation chamber to finish out at ambient temperature, around 78°.

I kegged the beer on 14 July 2017. The flavor was nice and tart, although at this point the raspberry comes through more in the aroma than in the flavor. I will have to see if that changes when I chill it and serve it carbonated; there might be some minor adjustments required prior to the festival, if that’s the case.

Because I wanted to keep this beer for home use too, I split it between two mini-kegs. Three gallons went into one, with 1.82 ounces of corn sugar boiled in 1 cup water (targeting around 3 volumes of CO2). The remaining 2 gallons or so went into another keg, which I force carbonated to around 2.8 volumes.

Final gravity for this batch was 1.013, down from 1.044. That clocks in at 4.1% abv–a very nice session beer!

Beer Update: Palaeotis Pils & Gondwana Pale Ale

Gondwana Pale Ale 1.5

I kegged the latest iteration of my Gondwana Pale Ale on 7 June 2017, adding two ounces of dry hops in a baggie at that time. Final gravity was 1.012, down from 1.053, for 5.4% abv.

Initial tastings show that this should be a pretty decent beer. It has a bit to mature yet, in that the yeast haven’t totally settled out and that seems to impart a harshness to the bitterness. I expect this should be much improved by the time I get back from Homebrew Con.

20170611_131001Palaeotis Pils 1.1

After brewing this beer on 20 May 2017, I started it at 50° and then let it ferment at 54° after a few days. I raised the temperature to 64° on 1 June, and then cold-crashed to 33° on 7 June 2017.

I kegged this beer today (11 June 2017). It has a final gravity of 1.011, down from 1.048, for 4.7% abv. At the time of kegging, I also added 1 tsp. of gelatin dissolved in 3/4 cup of water and heated to 152°, as a fining agent.

This beer tastes and smells amazing–I anticipate that it’s going to be a fine brew once it is clear and carbonated! Everything is on-point, and it’s a nice change after the disappointment on my Bohemian pilsner.

Big Batch Update: Saison, Amber Ale, Pilsner

There’s lots to report with kegging and fermentation for a few recent batches. So, here’s what’s new:

  • Thumbspike Saison 2.0

    • This might have had the quickest turn-around on any kegged beer I’ve ever done! I brewed the beer on 12 May 2017, starting with an 80° fermentation temperature. On 16 May, I raised the temperature to 85°. Everything really churned along, from start to finish (as you might expect with fermentation at those temperatures)! I kegged the beer on 20 May 2017, with a final gravity of 1.004. That works out to 6.7% abv. I’ve had it on tap for about a week, and it’s a pretty interesting and enjoyable beer. All of the ingredients melded together quite nicely, and I am pleased with the results. It’s a very refreshing brew for a warm afternoon on the patio.
    • My first impressions are that it has a very lightly fruity aroma, with a slight tartness on the flavor. Head retention seems pretty miserable at this point, but I don’t know if that’s a real feature of the beer or because I didn’t wash my glass from a previous beer before pouring this one.
  • Hell Creek Amber Ale 1.1
    • I brewed this beer on 14 April 2017, with a starting gravity of 1.060. I kegged the beer on 7 May 2017. Final gravity was 1.016, which equates to 5.8% abv.
  • Czech-ed Out Pilsner
    • This batch has the honor of being my first dumper, ever. I’ve weathered warm fermentations, low gravities, and incomplete fermentations, and have always soldiered through in the end. Alas, this particular batch just wasn’t any good. The culprit wasn’t infection, bad fermentation, or anything like that. It was bad hops! As noted in my original post, the late hop addition smelled really grassy. I should have known better than to add them to the kettle, but wasn’t quite that smart. So, I kegged the beer, carbonated it, and pulled my first sample…to a whiff of pilsner that smelled pretty much like freshly mown lawn, and not in a good way. It was almost reminiscent of jalapenos, but in any case was not reminiscent of what a good European pilsner should taste or smell like. Lesson learned!
    • In terms of fermentation history, I started fermentation at 50° on 9 April. I raised the beer to 65° on 21 April, and then dropped it to 33° on 30 April 2017. I kegged the beer on 14 May, at which point it had a final gravity of 1.011. This equates to 5.6% abv.