I haven’t had much experience with diacetyl in my beers. I’ve only brewed one lager, and that’s generally when you see diacetyl, because of the lower fermentation temperatures, and I allowed for a good diacetyl rest on the lager I did do, so I didn’t have any problems with it. That makes my latest conundrum all the more head-scratching. Both the bitter I kegged a while back and the dark mild I have in primary are loaded with diacetyl. In addition, I think both stalled out short of finishing fermentation. On the bitter, I was expecting a final gravity of around 1.009 and ended up with 1.013. That’s not terrible, really, though, so I let it go since it was stable. The dark mild, however, was at 1.019 after the yeast had been dropped out of suspension for a few days. I was also expecting around a 1.009. 10 points higher than anticipated is way up there. In addition, both have heavy diacetyl (think movie theater popcorn butter or butterscotch) off-flavors.
Since the bitter is already kegged, it’s off the yeast, so there’s not a ton I can do to it as is. For the dark mild, I tried rousing the yeast and I bumped the temp up to 74F. The 1.019 sample was on Friday evening. Yesterday morning I took another sample, and it was down to 1.016, so that’s progress. David said his bottomed out at 1.015, so I’m in that ballpark. He also didn’t have any diacetyl, so I’m hoping that it’s cleaning up now, and will be good to go here soon. He has his kegged now, and so if it turns out tasting good after carbonation, we’ll go with his for Bluebonnet and I’ll just give mine time and see how it turns out. For the bitter, I’m either going to make a yeast starter from a neutral dry yeast like US-05 and pitch it in when it hits high krausen, or I might take a couple of pints of yeast from the dark mild when it’s done and pitch it. Either way, I’m hoping the yeast will clean up the diacetyl left over from the WLP007 fermentation. My preference is probably to use new, clean yeast.
I’ve also heard that you can hook up your CO2 to your beer out post and let the CO2 bubble up through the beer in the keg while the valve on top is kept open, and this could help “blow-off” the diacetyl. I’m skeptical that will work, but I might give it a try. Otherwise, I’m not sure how I’ll have it ready to enter Bluebonnet, since my entries will have to be bottled before I leave on Sunday for Fort Sill.
Even if I can’t enter the bitter, or if we can’t enter my half of the dark mild, I’m still going to work on seeing if they can be fixed up enough where they’re good enough to drink. I’m confident that I can do that, at the very least. I used WLP007 that I bought less than a week apart from the same store, so maybe it’s a bad batch of yeast or something, who knows. I’ll probably avoid that strain from now on, though, since I’ve never had this problem before with other strains, even other English-style strains like WLP002.
In other news, I’ve be seeing lots of new homebrewers on my Facebook feed lately (or maybe not-so-new homebrewers, I just never saw their homebrew posts before, who knows with Facebook). I think it’s awesome so many people are getting into homebrewing. It’s a great hobby. You get to enjoy the process of making something yourself, and you have tons of control over the final product of your labors. Then, when you’re done, you have great beer to drink! I thought I’d share some of the lessons I’ve learned over the past couple of years, going from total newbie who didn’t know what he was doing, to award-winning homebrewer (it may just be one award so far, but I’m still pretty pumped about it!).
- Sanitation. It gets said over and over by pretty much every experienced home-brewer. Sanitation is the number one key to making good beer. I’ve been fortunate in that I have yet to experience first-hand the results of bad sanitation. I’ve had no infected beers. I have tasted some infected beers, though, and that’s not something that you want, unless you’re intentionally trying to sour beers, and that’s not something a new homebrewer should be doing, anyway. Everything…and I mean EVERYTHING…that the beer touches post-boil needs to be sanitized. A no-rinse sanitizer like StarSan or Iodophor is my recommendation. Both work very well.
- Fermentation temperature control. If sanitation is the number one key to making good beer, then fermentation temperature control is the number one key to going from good beer to great beer. My first beer was fermented in the pantry in the middle of summer in Texas. Even with the A/C running, the temperature in there was mid-to-upper-70s. Ale yeasts like it in the mid-to-upper-60s to ferment cleanly. Some Belgian strains can get up into the 80s and be ok, but even then, you generally will start fermentation lower and ramp up once active fermentation is complete. Higher fermentation temperatures can create all kinds of off flavors. In my first beer, an Irish Red kit from Northern Brewer, I had some pretty bad fusel alcohols, which give a “hot” or “solvent” type flavor. While the beer was still enjoyable, I knew it could be better. In order to attempt to better control my fermentation temperatures, I started using what’s called a swamp cooler setup. I used a bathroom in our house upstairs that wasn’t used much, if at all, and could be completely dark. I had a Rubbermaid tub and filled it up with enough water that the water level was even with the beer level in the carboy I was fermenting in. I would then drape a wet t-shirt over the carboy, with the tail of the shirt in the water. This would help with evaporative cooling of the carboy. I also rotated out frozen water or Gatorade bottle to keep the water around 65F, or whatever my target temperature was. I’d swap the bottles out when I left for work in the morning, when I got home in the afternoon, and before I went to bed at night. This worked pretty well, and I saw an improvement in the quality of my beer very quickly. It was still far from perfect, though, as there would be some pretty major temperature swings, especially during the day in the middle of the hot Texas summers. I knew I wanted to be able to more finely control the temperatures. Eventually, I moved to the setup I have now. I got an old, but perfectly working, chest freezer from Craigslist and an STC-1000 temperature controller from Amazon. Using a couple of different blog posts (here and here), I got the temperature controller wired up. The heating side goes to a light bulb inside a paint can that sits on the compressor hump inside the freezer, and the cold side goes to the freezer itself, which sits out of the way in the garage. It works perfectly. I’m able to keep the temperature within less than a degree of the target temp, even in the heat of the summer or the cold of the winter. The quality of my beer made another huge jump. I was able to create a saison with a pretty complex fermentation schedule. It started at 65F, and stayed there for 3-4 days, until active fermentation completed, then I bumped it up to 75F and let it rise up to there over the course of a couple of days. I kept it there for another 10 days or so before bringing it up one more time to 78F and letting it finish there. That’s the beer I won a gold medal for, so you can see the benefits of having good fermentation temperature control. While I haven’t taken much advantage of the ability to do lagering, I can now do lagers, even in the summer, if I so choose. The length of this paragraph alone should show how much I think about fermentation temperature control! It probably should be overall number 1, but without proper sanitation, fermentation temperature won’t get you anywhere!
- Yeast. If you're not pitching enough yeast, you could overwork the little guys, which can also cause some off-flavors. Generally, you can see increased levels of diacetyl from underpitching, and you can also see stuck fermentations (yes, this did occur to me with my problem describe above). There are a couple of ways to ensure proper pitching rates. For most 5 gallon batches, a single pack of dry yeast is going to be more than enough yeast. If you're using liquid yeast, even if it was produced that day and is 100% viable, you're going to be drastically underpitching. The best way to pitch liquid yeast is by doing a yeast starter. A yeast starter is basically a very small batch of unhopped wort. For every 10ml of starter volume, you'll need 1 gram of DME (dry malt extract). So, for a 1L starter, you'll need 100g of DME. I like to use the lightest DME I can find, so you're not adding any color to your wort. Boil your water and add in the DME. I usually boil in a seperate pot, then pour the water into my pyrex flask, then add the DME. Bring the DME/water mixture back to a boil and let it boil for at least 15 minutes. After you've cooled the starter wort down to 70F (with such a small volume, this is pretty quick in an ice bath in the sink), give it a good shaking to aerate the yeast (or, if you have the setup, you can actively oxygenate the yeast), then add your yeast. Cover the top with a sanitized piece of foil. If you have a stir plate, before covering, you'll need to drop in your stir bar as well, then put it on the stir plate. I use the lowest setting that I get a vortex going at. If you don't have a stir plate, no problem, you'll just need a bit bigger starter, and will want to shake your starter periodically. Mr. Malty's starter calculator is a great resource for determining how big of a starter you're going to need based on your batch size, the starting gravity of the beer you're making, how old the yeast is, and whether you're using a stir plate or not. After 24-48 hours, your starter should be pretty much done. At this point, you can pitch the whole thing into your wort, or you can put it in your refrigerator to get the yeast to drop out of suspension. I generally will cold crash for a day or two prior to brew day, then take the starter out of the fridge at the beginning of my brew session and let it warm up to room temperature. When I'm ready to pitch, I'll decant off most of the liquid, leaving only the yeast cake plus enough liquid to swirl around in the flask and have a slurry to pitch. It all goes into the wort at that point, and you're only adding a negligible amount of extra wort in. You do also want to be sure you're not overpitching. Check the starter calculator to see how many yeast cells you need for adequate pitching.
If you’re doing the three above things, and doing them well, you’ll make great beer. It doesn’t matter if you’re a 100% extract brewer doing only recipe kits you buy online, or if you have the ultimate 3-tier all grain system and you’re making your own recipes and crushing your own malts.
Happy brewing everyone!
