Low Dissolved Oxygen (DO) Brewing Lager
Every few years there seems to be some radical underpinning of the brewing word that comes under assault. Remember olive oil instead of oxygen? Saisons fermented above 80F? Dark candi syrup the key to dark Belgian beers? Dry hopping during fermentation? After the debate calms down sometimes brewer's shift their process en masse, and sometimes most of them say it isn't worth the expense/effort/trade-off.
Two things I love about homebrewing are the passion it stirs up, and the flexibility it allows for testing novel techniques. After my friend Trevor talked my ear off about it, I read the German Brewing Forum's collaborative treatise on low dissolved oxygen (Low DO) brewing, The elevator pitch is that to mimic the character of large/classic German breweries (who steam purge equipment and deaerate brewing water) homebrewers need to go to great lengths to limit oxygen pickup on both the hot and cold side. This includes pre-boiling water, dosing oxygen-scavenging sodium metabisulfite, underleting the mash, and spunding their kegs. The supposed payoff is a near mythic German “it” maltiness that Ayinger, Paulaner, Weihenstephaner et al. create that you never taste from craft-brewed examples of helles, dunkel, bock etc.
I decided it was worth a try!
The problem with the method is that, according to the authors, even slight deviations may render the rest of the effort worthless. As little as 1 PPM of oxygen for a few minutes is enough to destroy all of that hard work! I did my best, but didn’t have the effort to go entirely on-method. On the hot side, I used a copper wort chiller (cleaned with StarSan to remove most of the tarnish) instead of stainless steel. On the cold side, I did a more modern lagering method warming rather than cooling towards the end of fermentation to ensure complete attenuation.
The other problem was that I misunderstood the amount of metabisulfite to add. I executed a no-sparge mash as suggested to avoid the risk of aerating during the sparge. The problem was that I dosed my entire mash volume with the rate of campden that they called for (100 mg/L), without accounting for the lower rate (10-25 mg/L) suggested for the sparge. Apparently I wasn't alone because version #2 of the treatise suggests 55 mg/L metabisulfite for no-sparge brewing.
To throw another variable into the mix, I used Weyermann Barke Pilsner for the first time (a sample from BSG, thanks!). This is a new release, an heirloom malt that is lower yielding in the field, but supposedly fantastic to brew with. It is said to replicate some of that elusive maltiness that is difficult to capture for non-German brewers.
The recipe is somewhere between a Pilsner and a Helles (with the other half currently fermenting as a Brett/beet saison, more on that some other week...)
Low DO Pilsner-Helles
Smell – Mostly clean aroma, just a hint of gentle yeasty-apple-fruitiness. Nose isn’t especially malty, I might have confused it for an American Premium if I didn’t know what I was being served. Appropriate waft of sulfur, not out of place. Luckily a "peanut butter" aroma it had early in lagering is gone.
Appearance – Pretty white head, good retention and lacing. One of the palest beers I’ve brewed given the avoidance of Maillard reactions in both malting and brewing. Moderate haze, not off-putting.
Taste – First wort Saphir hops provided a pleasant bitterness with some faint herbal notes. The finish exhibits big doughy malt, more reminiscent of a no-boil Berliner than anything else I’ve brewed. Finish has a hint of chemical-bitterness.
Mouthfeel – Light and crisp, as expected given the low OG. Firm carbonation.
Drinkability & Notes – A solid beer? Sure. Unique? I think so. Worth all the extra effort? Not for this batch anyway! It’s actually one of the lagers I’ve enjoyed least from my last few years of brewing. Not that I brew many, but the lingering flavor isn’t one that calls out for another sip.
Changes for Next Time – Adjust the sulfites to be more in line with the clarified suggestions reduce by 50%). Try going all-in on the Helles recipe, including some caramel malts to see if their flavor shines as noted.
Low DO Barke Pilsner Recipe
Batch Size (Gal): 11
SRM: 2.9
IBU: 21.8
OG: 1.043
FG: 1.009
ABV: 4.4%
Brewhouse Efficiency: 63%
Wort Boil Time: 65 Minutes
Malt
------
100.0 % - 20 lbs Weyermann Barke Pilsner
Mash
-------
Sacch Rest - 30 min @ 152 F
Hops
-------
4.00 oz Saphir (Pellet, 3.00 % AA) @ First Wort
Extras
--------
1.00 Whirlfloc Tablet @ 5 mins
1.00 tsp Yeast Nutrient @ 5 mins
Yeast
-------
Saflager W-34/70
Notes
-------
Brewed 8/7/16
Boiled 18 gallons of water (half distilled, half filtered DC) added 12 g of CaCl and 1 tbls of 10% phosphoric acid. Chilled to 160F, added 15 campden tablets (6,600 mg sodium metabisulfite for 68 L, about the 100 mg/L suggested), crushed. Underlet mash after purging under false bottom with CO2.
Poorer than expected efficiency, likely thanks to a less vigorous crush, brief recirculation, and no sparge.
Chilled to 72 F and transferred 6 gallons out and pitched the Bootleg Biology "Mad Blend." Left at 65 F to ferment. Not aerated initially. 15 seconds of pure O2 after 3 hours, and 6 hours.
Chilled the remaining to 58 F (underestimated the amount of ice needed) and pitched 34/70 (rehydrated, then given an hour on a stirplate with 2 L of diverted wort, and then another hour in the fridge at 48F to acclimate. Not aerated initially. Left at 48F. 15 seconds of pure O2 after 3 hours, and 6 hours. Upped to 52F after 18 hours to ensure it starts quickly.
8/11/16 Moved Saison out of the cold room, to ambient ~75F to finish out. Super sulfury.
8/15/16 Slowly started warming the lager portion 3F each day.
8/20/16 Kegged (well purged) the lager portion with 5.75 oz of Light DME. Left at 65F with the spunding valve set to 30 PSI to carbonate to mid-2s volumes. FG 1.009.
10/8/16 Added 14 oz of shredded beets to the saison secondary. Still pretty sulfury, hoping this helps!
February Kegged.
Posts
22 comments:
Indeed it is an absurd amount of effort - not to mention the absurdly long cold fermentation and lagering schedules. After 3 tries at it I understand the merits but it'll likely be a process I use only a couple times a year. My 3rd and final attempt for 2016 - coincidentally the only one with the proper ~50 mg/l SMB dosage - is currently lagering. Will be interesting to see if that "peanut buttery'ness" was due to SMB overdosing.
Lets break this down, in a effort to help others.
Improper dosage of SMB
Did not use Acid malt(it carries flavors over that are desirable, and in the paper)
Did not follow the recipe (caramalts and/or a malt blend is essential to the proper flavors)
Did not mash per the sheet(though I will be lenient here)
Did not use any of the recommended yeast strains(infact used 34/70 which we go out of out way to say to avoid)
Did not ferment as per the schedule
Did not spund
As you can see short of not adding SMB, this beer was brewed with the same standard methods the paper say to strictly avoid. I am not surprised at the result.
I don't know if it is a general problem to comprehend or follow instructions properly but hopefully others can break out of these habits and actually give it a proper go!
Bryan
It’s OK, you don’t have to be defensive! It’s just beer! I made multiple adjustments to my usual wort production process in addition to SMB (e.g., underletting, no-sparge, gentle boil, first wort hopping). And I did spund, although I had to add malt extract to ensure complete refermentation. The paper mentioned acidulated malt for pH adjustment, but I used phosphoric acid because I prefer the control.
I saw the note on yeast strains, but 34/70 is what I had on hand. I've had good results with it and this fermentation schedule over the years. In fact the dark lager I brewed with the yeast harvested from this batch doesn’t have any of the same off-flavors. I'm not clear why it would cause problems for a beer brewed with this method compared to others?
I agree with the improper dosage of SMB, which was a result of following the instructions in the original guide (I brewed before the clarification was posted). I’m glad I didn’t waste effort on the few things I skipped, because this alone was likely enough to produce off-flavors! I’ll try again, sticking even closer to the refined process.
The problem with a method this precise is that you can always say something wasn’t followed. If it doesn’t yield good results next time you can say I don’t have a DO meter or that my palate can’t appreciate the subtle flavor etc.
it's not a paper, it's a pdf.
so does one need to pitch a boat-load of yeast, since no O2 = low growth?
It is funny you say peanut butter, because I had that in my weizen and my Kolsch definitely has some DMS.
I like the idea of this technique and I am always trying to make the perfect beer, but the potential pitfalls and the razor slim margin for error make it tough to enjoy the process.
Andrei, yes. I'd suggest reading the linked pdf because I didn't go into all the details (and didn't follow all of the fermentation suggestions). I wanted to focus on the hot side as they noted that even Guinness and Budweiser have "Low DO" notes, so I assumed as long as I had a quick start to fermentation and minimal O2 pickup post-fermentation I'd have a good beer.
I was aware this LDO movement and I plan to try it. I reread the pdf again and it have an immediate benefit. I used potassium metabisulfite for dechlorinate water. Now I read potassium is harmful for the mash enzymes. So I have to switch to SMB. Thank you for this article.
I think it's a bit of a shame that proponents of this method are so haughty about it. The pdf in question provides no real evidence that the method works and there doesn't seem to be any, beyond a bunch of first-person anecdotal claims (which are notoriously unreliable, since we're all heavily subject to a range of biases) that individual brewers have felt it improves their own beer, and the claim that a bunch of commercial breweries use the process.
I'm not saying there's nothing to it (though, if I'm honest, I'm sceptical), but I think it would be good if fans of the method were a bit more patient with healthy, scientific scepticism and tried to come up with some better evidence for it than "Try it. Trust me, bro." A decent-sized, double-blind tasting trial would be a start.
I had similar notes in my Brake Pilsener malt Pils. The maltiness was underwhelming. Any thoughts with using melanoiden malt to add that flavor/darken the color to something more akin to Urquell?
You certainly could add some melanoidin, I did on a previous helles and liked the results. If all you want is color, a tiny amount of dark malt is the standard response.
What about adding diastatic malt to help with the efficiency?
The Pilsner malt has more than enough to self-convert. The issue isn't enzymes, but the efficient extraction of the sugars post-conversion. I should have just assumed a 10% drop in efficiency given the changes to my standard process. Hopefully I'll work out the kinks on round #2 in a few weeks!
I'm going to try one this winter.
I just want to encourage you not to give up after one attempt. I was one of the people who developed the ideas/methods and wrote the guide, and it took me personally about 10-12 batches before I felt like I was getting my system dialed in for low oxygen brewing. That was on top of all of the lessons learned by trial-and-error from the other brewers working on the method.
Believe it or not, we don't want brewing this way to be complicated for the sake of being complicated. I'm trying to get my turnaround time down to 3-4 weeks grain to glass, and on top of that I've made a lot of optimizations to cut down my brew day length to under 6 hours start to finish. I'd love to get that down to under 5 hours.
If I can offer some unsolicited advice, here's some of my thoughts:
1) A recirculated no-sparge system will take care of any efficiency issues you have and in theory offer lower oxygen pickup than any other kind of homebrew system. Here is a description with pictures of my setup:
http://forum.germanbrewing.net/viewtopic.php?f=15&t=321
With this system, a Hochkurz at pH 5.2 with 15 min@64c 30 min @72c 10 min@76c gets me 38 PPG efficiency and will take a 1.051 OG beer down to 1.008.
I've replaced the floating lid with a 14" flat bottomed stainless steel cake pan that floats on the mash with zero airspace and covers over 95% of the liquid surface area.
2) The SMB dose is system dependent and depends on how much oxygen you pick up. Some people are so rough on the wort that 100 mg/l in a no-sparge mash still probably wouldn't be enough protection. For others, 25-30 mg/l may be enough. You can also try mixing SMB with ascorbic acid (eg 25mgl each) as we've done some preliminary experiments demonstrating that it can act as a drop-in replacement for SMB and maintain the fresh grain flavor post-mash/boil. See:
http://forum.germanbrewing.net/viewtopic.php?f=49&t=539
3) My fermentation nowadays goes like this: pitch at 6-7c, ferment at 9-10c, then rack with 1% extract left and as little yeast as possible. Mature at 6c until FG then to 3c. If you're confident in your measurements, you don't need a spunding valve. With a cooperative yeast like WLP835 you should be able to go grain-to-glass with good clarity in 4ish weeks.
Too much yeast carried into lagering and you'll have autolysis spoil the low-oxygen malt flavor before the beer ever clears.
4) If your finished beer tasted like a no-boil beer, I wonder if you didn't boil enough. I've gotten DMS in a few of my beers before I dialed in my boil and it wasn't nice. Heat stress is just as big of a concern though. The boil is a very Goldilocks thing.
http://forum.germanbrewing.net/viewtopic.php?f=53&t=440
5) Not all pils malts are equal. There is a flavor difference between a bright pils closer to 3 EBC (Swaen, Avangard, etc) that tastes hay/grass-like and a darker pils at 4 EBC like Best that is closer in flavor to pale ale malt (but not quite). And of course there is variation lot to lot. 100% 3 EBC pils is gonna make a boring beer. I would cut it with vienna, pale ale, etc. I have been happy with 77% wey barke + 20% vienna + 3% carahell/carared, but want to switch over to using a darker pils like Best.
6) Biological acidification (i.e. sauergut in the mash and boil) is a huge deal. Like, almost as big of a deal as LoDO. It will lock your mash pH in place even with no-sparge, massively speed up conversion, give you even brighter wort with even better flavor, improve break in the boil, give you a faster and more vigorous fermentation/maturation, make your beer clear faster, make your foam stickier and longer lasting, and massively improve the flavor of the finished beer. More on that here:
http://forum.germanbrewing.net/viewtopic.php?f=46&t=533
http://forum.germanbrewing.net/viewtopic.php?f=46&t=537
I hope you give the method another go and get better results next time.
Oh, I forgot one more thing:
100% FWH in my experience is overwhelming and harsh in a bad way and covers up a lot of the malt flavor. I wouldn't go over 30%. I actually don't FWH nowadays, and instead use 60 min + 10 min boil additions (~1g hops / liter at 10 min, the rest at 60 to hit your IBU target).
Cheers for all of the advice and links! Really appreciate it. Looking forward to attempt #2.
Although I agree that the paper could be better at referencing the literature, the only unproven part is the adaptation of a commercial method to homebrewing.
The most used textbooks in the world, Künze and Narziss, clearly favor this process for Helles Lagers (but not for Dunkel nor for Weissbier).
So, one can say more evidence is needed in a homebrewing scale, but one CANNOT say there is no evidence.
Do either of those sources specify why it is preferred for Helles and not the others? It's great that it is in a text book, but it could just be for the lighter color, shelf stability, or some other factor other than a particular malt character.
From a professional brewer's prospective, that "paper" is a bit of a joke. The fact that they are talking about DO levels in finished beer in ppm is funny. Of course the beer tastes oxidized. On the commercial brewing side, anything above 70ppb TPO (.07ppm) in packaged beer (bottles) is considered a MAJOR problem for us. Seeing sub 10ppb in kegs or brite tanks is not abnormal.
Luckily for homebrewers we don't have to deal with our bottles being sent out into the cruel world of warm storage and indifferent shipment!
We asserted that standard homebrew packaging processes result in DO levels of 1 ppm or more, and that you really need to be under 100 ppb. We asserted that spunding is the easiest way for a homebrewer to achieve that.
I'm not sure how that makes us a "joke".
Post a Comment