Diacetyl: What the ale is wrong?

The scientific definition of diacetyl is a vicinal diketone with the molecular formula C4H6O2. In simpleton terms, it is a movie theater butter or butterscotch flavor. Yes, I have heard that movie theaters actually are using diacetyl when they ask you if you want your popcorn buttered. Is this fact? I’m not saying no, but I wouldn’t doubt it. But diacetyl is a common problem in homebrew. I have even had a lot of commercial examples that have loads diacetyl. But this is is not a flaw in some English style beers.

So how does diacetyl get in our beer? Diacetyl is produced during fermentation.  It starts to show up in the low krauesen phase. Huh? Low krauesen? This is the phase of fermentation when the yeast has finished growing and you’ll start seeing a foam wreath develop in the middle of the surface.  The yeast has not completely adapted to the environment and ready to start metabolizing those sugars you worked so hard to create.  Ok, maybe I need to go in depth on the yeast development cycle one day.  It is quite interesting what all those yeasts do during fermentation.  Back to diacetyl.  It can start showing up in the low krauesen phase and the yeast will start cleaning up by products that were developed during late krausen phase.

Ok, so now we know when diacetyl can show up in our beer. Now why am I tasting it in my beer Well, it can be a lot of things.

  • If you have a long lag phase (from when you pitch to when you get to the growth phase of fermentation) which can be caused from poor yeast health or insufficient aeration.
  • Some bacteria strains can cause diacetyl production. Here is where I use that sanitation word. Any homebrewer has heard sanitation probably 3.7 million times. Seriously. Sanitation, so that’s 3,700,001 times.
  • Premature racking out of primary. See earlier? You might not be able to see when your beer in late krauesen. So make sure your beer is done fermenting by checking your final gravity for a couple days straight to make sure your gravity is not dropping.
  • Under pitching. Huh? So you’ve never made a yeast starter? You’ll improve your beer ten fold by making yeast starters. Take the plunge, get a stir plate and you can make sure you’ll have enough yeast to pitch.
  • Too much oxygen. Wait one minute. I bet you remember me mentioning earlier about insufficient aeration? Well of course I did, there can also be too much. Yeast absorb all the oxygen it can during the growth phase. Well if there is too much oxygen there will still be oxygen lingering when the fermentation is over. Most homebrewers don’t filter their beer. If there is still oxygen left over, the yeast will still be feeding off of it and still trying to go through fermentation phases. Also minimize oxygen exposure after fermentation started, e.g. while racking to the keg or bottling bucket.
  • Increase your fermentation temperature. That is use a diacetyl rest. A diacetyl rest is a common practice for lager beers. When you warm up the yeast it becomes a bit more active and it will help clean up the yeast. You can also use a diacetyl rest for ales, but most of the time you are fermenting at the correct temperature for the diacetyl to be cleaned up.
  • Use a less flocculant yeast strain. Flocculation is the state of yeast of being clumped together and falling out of solution. If the yeast is still in suspension it will be a little more efficient when cleaning up diacetyl.

Diacetyl will most of the time be a flaw in lagers, but not in every ale style. It is acceptable in a Czech Pale Lager, English and Scottish style beers and also a dry stout.

I’m sure we have all had this problem show up in our beers. This is one of the major issues that I fight with, especially since I started doing lagers.

Relax, don’t worry, have a homebrew.

How to Brew
Beer Judge Education Course

What I Learned: 2013 National Homebrew Competition

What did I get out of from this year’s National  Homebrew Competition? One that I cannot complain about my scores at all. Two, it is pretty awesome that all of my beers went to their respective Mini-BOS. Three, what can I do to make my beer stand out against the competition in a Mini-BOS? The beers I sent to this year’s NHC were just five beers I had around the house that were worth submitting to this year’s competition.


Three of them are my go to beers the other two beers were experiments per se, and they scored the best!

Chocolate Hazelnut Porter (BJCP Category 21A) – this beer has won m
e quite a few awards. It advanced to the second round of 2011 NHC with the same recipe, and it’s normally a holiday time brew. It’s usually on tap at my house up until May. I’ve almost blown that keg this year.

Judges Overall Impression –

Judge 1 – Certified: Great example of your chosen style and description! Score: 41

Judge 2 – Certified: Well balanced cocoa & hazelnut – Roasted grain & other porter characteristics are subdued & might benefit from being brought forward a bit. Score: 38

Hoppin’ Oaked Saison Squared (BJCP Category 22C) – woah! This scored a 41? I entered it as a Saison IPA aged on medium french oak chips. I brewed this beer for an intra-club competition and I entered this solely to get feedback from people outside of my homebrew club. I’ll enter this into other competitions just to see how it will do, and as the judges noted, I needed to be better on my description which the next competition I entered it into, I was a bit more descriptive.

Judges Overall Impression –

Judge 1 – Certified: An excellent beer. The flavors are well matched and compliment each other. You need to do a better description in the future and don’t make the judges guess what the base style is. Score: 43

Judge 2 – Provisional: An interesting beer which as much not a saison as its not an IPA but its nice the wheat and oak makes for a great texture. While Belgian yeast and hops provide a nice bubble gum spiciness, very unique, slightly fusel, but not solventy. For the competition I judged it as an IPA with Saison aspects. Score: 40

Let’s Stout It Out (2012) (BJCP Category 13F), the 2011 version of this turned out really good, but the only problem was that I only brewed a 3 gallon batch and it was really good. So in 2012 I tweaked the recipe a bit based on the success I had with my Regal Porter. I used the base malt I had on hand and also changed to Scottish yeast, which my little secret in 2012 on the malty beers I brewed this year.

Judges Overall Impression –

Judge 1 – Rank Pending: A good representation of the style. Fermentation was well done in order to not be hotter than it is. The alcohol aroma is a bit much. Score: 37

Judge 2 – Master: Has al the right flavor elements, but higher alcohols are a bit too fruity / floral and harsh / hot. Be sure to pitch HUGE for high-grav beer like this, oxygenate well, keep temps under control. Consider different yeast strain. Score: 34

Two Sides of the Schwarz (BJCP Category 4C) – ok I have pretty much had a Schwarzbier on tap at my house since I got a fermentation chamber. I received really good feedback from 2012 NHC so I tweaked the recipe a bit. 2012’s was a bit too roasty for the style. So I backed off of it a bit, and I get a lower score in 2013. Live and learn and keep brewing it.

Judges Overall Impression –

Judge 1 – National: A fairly nice beer that suffers from a little diacetyl. Aside form a diacetyl rest at 68 degrees F 75% of the way through fermentation (75% x (OG – FG)) maybe aerate more and/or lager longer. Otherwise nicely done. Score: 35

Judge 2 – Certified: This is a good beer. That has balance between the base male and the roast. Also has enough hops to balance the malt. Score: 34

Regal Porter (BJCP Category 23A) – this was another experiment at the Wickham Brewery and it turned out phenomenal! This was brewed as an Imperial Porter. Sweet, chewy, luscious, and it is awesome with some ice cream! I only hope I can recreate it. The experiment for this beer was to do a parti-gyle brew day. Which if you haven’t done one, it is a long brew day, but you get TWO beers out of it, which is spectacular. The beer had almost six months of age on it and it is just getting better with time. I’m really proud to get a 43 on this beer.

Judges Overall Impression –

Judge 1 – National: Very well made beer with no major technical flaws. Imperialzing this beer amped up the good parts of the base style without adding any unpleasant harshness. It may benefit slight with more carb & perhaps cutting back on the highly kilned malts a touch. Score: 42

Judge 2 – Certified: An excellent Impl porter. Roastiness, malt sweetness, hops & alcohol are all bumped up but not harsh or conflicting. More carbonation is needed to improve aroma, appearance, and to maybe thin (dry) out the flavor a little. Score: 44

I learned quite a bit from most of these sheets. The one glaring thing is when submitting specialty beers, be very descriptive of your beer. You do not want to keep the judge guessing. After judging at my local competition this weekend I totally I understand. I was judging fruit beers and there were a couple beers that did not state the base style so I had to make assumptions. After we were done judging the competition I found the second bottle of the entry and the name says what the style was. So there you have it and of course I was wrong on one of the base styles. But it still scored well, I at least got the category number right.

I submitted the same five beers to my homebrew club’s local competition, and I will compare those sheets with these judge comments. Should be interesting. Hopefully this will kick start me to write on my blog more.


Deciphering Judge Comments

I think I’m going to do a series on the blog about this. I just entered two more beers that have been in competitions this year. This will be something good to write about in an upcoming blog post.

I’ve entered quite a few homebrew competitions, and I have really tried to take the feedback as constructive criticism. It is hard to take when someone rips your beer. I’ve sent soured beers, flawed beers, and some good beers. I have been fortunate to get some good feedback, but I have never really been told your beer sucks, which is a good thing. When studying for the BJCP, I learned that the overall impression is not just your impression, but using your brewing knowledge to suggest what the brewer can do to make that beer a better fit into the style in which it was entered. What will make this beer a 50 point beer. I’ll give you a couple examples of what judges have said on my sheets, and just maybe this will help lure you to enter more competitions.

Category 4C: Schwarzbier – Two Sides of the Schwarz

2013 National Homebrew Competition

Judge 1 – National – A fairly nice beer that suffers from a little diacetyl. Aside form a diacetyl rest at 68 degrees F 75% of the way through fermentation (75% x (OG – FG)) maybe aerate more and/or lager longer. Otherwise nicely done.

Judge 2 – Certified – This is a good beer. That has balance between the base malt and the roast. Also has enough hops to balance the malt.

2013 War of the Wort

Judge 3 – Recognized – Light smooth roast with malty richness made a very nice beer. Hop character was a little low in flavor and ok to be hidden in the aroma. Would like to see a little more hop flavor, although with a lighter roasted schwarz this is not completely a bad thing. Very nice beer!

Judge 4 – Certified – Enjoyable well brewed schwarz. I think the bitterness is a tad too intense. Suggest reducing hop bitterness and backing down a little on the sharpness of the roast. Very dry.

Let me note, these entries were from the same keg. So technically unless something was wrong with the bottle, these should have been the same beer. But you know that finicky home brew. So what can I do to make this beer fit better into style? One judge noted diacetyl. Shall I worry too much about the diacetyl that was noted? Not really since I should make my diacetyl rest good practice. It wasn’t a major flaw noted. So what did the judges tell me that will make this a 50 point beer? Not too much. Judges 3 and 4 both noted hop character, but in different aspects. This beer has been lagering since January so of course hop flavors would have dropped out. Judge 4 was the only one to note hop bitterness was harsh. Was it hop bitterness, or did I extract too much roasted bitterness? To conclude, they all four thought it was a well brewed beer, but it wasn’t a great beer. What can I do to make it great? Other than the detected diacetyl, which I do not typically detect in my beers until someone tells me. Mirror? Hello? Then the more hop character. This style has a low to moderate hop character, so I do not believe I will change my hop schedule. My major issue that I get out of these four comments is the diacetyl I need to work on my lagering practice. Patience is not my friend, so that means lagers aren’t my friends either, but I do enjoy drinking a well brewed lager.

Category 13C – Oatmeal Stout – Quaken Oaten Stout

2013 Bluff City Extravaganza

Judge 1 – Non-BJCP – a very drinkable beer. I would have liked some more sweetness and or oatmeal character. As the beer warmed I noticed a slightly tinny/metallic notes though were not overwhelming.

Judge 2 – Non-BJCP – Beer suffers from off flavored and over carbonation. Not sensing oatmeal character. Could be a good beer with tweaking.

2013 War of the Wort

Judge 3 – Provisional – Good beer very drinkable. Maybe try changing mash temps to try to get more unfermentable sugars to balance the bitterness. I would like more oatmeal character too.

Judge 4 – Certified – the beer was not too far off style, but balance was problematic. Tweaking of recipe or procedure is recommended. Needs more oatmeal sweetness/slickness.

These are two different batches, so technically these are different beers, but I want to show you that the judges’ comments are not too different. But it is the same recipe with similar ingredients I could not get Maris Otter for the War of the Wort batch, so I did substitute the base malt for what the home brew shop had in stock. I did have a slight issue with the beers sent to the Extravaganza being over-carbed. Was my fermentation not complete? Apparently not. That was a ding there. That beer sat in the carboy for 3 weeks, guess I needed to raise my fermentation temps up towards the end of fermentation. I am baffled by the way  WLP002 flocculates and it appeared to finish pretty quickly.

I have had trouble getting that oatmeal sweetness/slickness that judge 4 mentioned. Body has been a problem for me with this beer. I need more dextrines. Is the way I handle my oats wrong? I use Quaker oats from the grocery store. Should I use quick oats? Should I cook the oats like I would for breakfast before I mash? I do bake the oats to try to bring out more nutty characters. I will need to ramp up my saccrification rest to 156, I normally mash at 154. This will also help get those long chained sugars I need for more dextrinous wort. This is a beer I want to to nail down as I really enjoy drinking this style.

I know this beer is not a 30 point beer in the oatmeal stout category. It fared better in the War of the Wort. My goal is to perfect this recipe. I will.

How many beers have you let your friends drink and they tell you it’s awesome? It’s great? Well this oatmeal stout, no one has told me to my face it is not quite right, as an oatmeal stout that is. Do they know better? Some of them do. I’ll still drink this keg, sorry rose bush, you’re not getting this beer. I know this, but I wanted some feedback on it outside my circle of friends.

I hope this kind of put a bug into your ear about entering competitions and how they can help you brew better beer. If you only enter one a year, enter the War of the Wort next year, if you enter two, enter HBAMM’s Monster Mash, which will be held in the Oct/Nov time frame.