The Other Dreaded D: DMS (Dimethyl Sulfide)

Last week we tapped our second light-colored lager, a German Pils - made with 100% pilsener malt. Our fist light-colored lager, an American Premium, suffered from diacetyl to the max (not enough yeast, no diacetyl rest). This time around I managed to get rid of the butter, but handily discovered another flavor: DMS.

At first I wasn't quite sure what I was tasting. The beer is super clear and beautiful, but yet - what is that? Unlike our previous lager, this wasn't terrible. There was just too much of something unbalancing the beer. After having a couple beer-judge friends taste it, the culprit was identified - Dimethyl Sulfide.

A small level of DMS in lagers is acceptable. In fact, now that I know what it tastes like (think corn when drinking a Schlitz), I can pick it out in other beers. Ours just has a too much of it - thankfully there's enough hop bitterness in there to cover it up some, especially when it's nice and cold. But we pitched plenty of yeast, and cooled fast by pumping ice water through our immersion chiller, so....

What Causes DMS?
The first thing each judge asked us is if we boiled with the lid on. Nope. But, I don't think I boiled hard enough to drive it all off. In an effort to save gas and avoid kettle caramelization, I've been experimenting with a less-than-rolling boil - just getting it going enough to be boiling. Well, no more wimpy boils here, now that I know that a boil isn't just to sanitize and add flavor/hops to the wort, it's also supposed to drive off stuff you don't want in there. So it's time to crank it up a bit (but not so much that hot wort is leaping out of the kettle!). In general, a 10-15% evaporation rate per hour seems to be the goal. So if you start with 7.5 gallons, you want to boil off around 1 gallon or a little more in an hour, or around 1.5 gallons for a 90 minute boil. In the meantime, I'm just going to bring the iced keg to a 4th of July party, where I'm sure it'll get sucked down pretty quick on this hot Chicago day (update: it did). Cheers!

Diacetyl Rest - Go for a Week!

In mid-late 2009 we brewed our first lager, an Oktoberfest. For our first lager (and having no temperature control device, just a fridge), it went really well. The final beer was malty with a nice hop bitterness, beautiful amber color, and crystal clear from the lagering (why filter a lager?).

I brought a sample to a Chicago Beer Society event, and one guy said he tasted a hint of diacetyl (a buttery by-product of lager yeast). I was unsure of this, having yet to train my palate for this flavor. But everyone really liked it and drained the bottle. Next day I brought a sample over to Half Acre brewing, and had a little lager schooling from head brewer Phil, who also tasted just a hint of the buttery diacetyl. After drinking this brew for a week or so, I was able to just pick it out too. He asked if I did a diacetyl rest, and I did do one for a few days. Phil said to just leave it out for a week! So next time, a week it is!

We've since brewed another lager, an American Premium. We had excellent temperature control, never letting the beer get above 50F (we pitched in the upper 40s), and a post-fermentation sample tasted great. So instead of doing a rest, I  just crashed it down to 36F and will be kegging it up soon for the super bowl. We'll see how that goes, but I think it should be fine. The yeast I used, Wyeast 2007, didn't say anything about needing a diacetyl rest, whereas the 2308 Munich Lager I used before clearly states that it benefits from one. So I guess the moral of the story is to read up on your yeast, and if a rest is needed, make it a week - cheers.

Brew Day: Super Jim Lager

Today we're brewing our second lager, and are dedicating it to a good friend of ours who passed away. He loved his American lagers, and the very first beer we brewed over a year ago was an extract lager that we named after him, calling it Jim Style. Unfortunately, it was Kool-Aid beer - warm water, extract, sugar, dry yeast (the Cooper's kit). It wasn't all that great. Now we're doing it right, or at least better, with some all-grain action.

The recipe is based on the American Premium Lager recipe from Brewing Classic Styles by Jamil Zainasheff. As usual, we've upped the hops slightly to quench our hop teeth. The recipe only called for 1.25oz of German Hallertauer at 60 minutes, but since we have 2oz, we'll likely toss the rest in when there's around 20 minutes left in the boil.

Below we'll breakdown the brewing process:

5 days ago: Made a 2 liter starter of Wyeast 2007 Pilsen lager. Hopefully it's enough, our LHB only had one pack. It actively fermented the entire time (we added some yeast nutrient), so it should be good. We'd feel better using a starter with another smack pack (like last time, which worked very well), but oh well - we'll just have to see.

9:45am - Mash in. Hit our target temp of 152F (maybe 151F by the time we had the lid on, close enough). Now we wait 90 minutes.

11:15am - Only lost 1 degree during the mash - success! Now to set the grain bed and start sparging. We use the fly sparging method using a colander in the top of the tun (slowly sprinkling water over the entire grain bed). Our goal is to collect about 8 gallons, which will take quite a while.

12:15pm - Might be sparging a little too slow, not even halfway there, speeding it up a bit. Being very careful to not let the water level fall below the grain bed.

1:00pm - Sparge complete. Time to move outside to boil.

1:11pm - Shooting for a pre-boil gravity of 1.040, we got 1.039 - not too shabby.

1:22pm - We're boiling. Got to love the propane burner. When we were doing this on our stove-top it would take almost 2 hours just to get to a boil.

1:50 pm - Bittering hop addition: 1.35 oz. Hallertau.

2: 30pm - Added .65oz Hallertau. Also added wort chiller (to sanitize w/ heat) and whirlfloc (to help all the protein/break material settle to the bottom so it doesn't wind up in the fermenter).

2:40pm - Added yeast nutrient.

2.50pm - Turn off heat, and begin cooling. A reading for the Original Gravity (OG) showed we were off our target of 1.053, we had 1.046. Perhaps we didn't boil vigorously enough, which was intentional because we didn't want any carmelization to darken the beer's color. Regardless, it'll still be good. We scaled this beer to a mash efficiency of 75%, and we came out at 74%.

Below are some pics of our new cooling process. After cooling as much as we can with the garden hose hooked to the immersion chiller, we switch over to a cooler full of ice water (and snow this time of year) with a sump pump, and hook that into the immersion chiller. This works very well.


3:30pm - Temp down to 45. Sanitizing fermenter and letting break material settle to bottom of boil pot.

3:50pm - Transferring wort to fermenter. Decanted and pitched the starter at 46F. Most of the foam you see below is just from aeration - trying to get as much oxygen into the wort as possible to help the yeast reproduce. There a little Star San foam in there too. This will be our first time using the new fermentation chamber, a Sanyo SR-4912M with a Johnson A419 temperature controller. There was a soda can dispenser on the door, which we just cut out so we could fit our carboy w/ milk crate in there. You can't see it, but we also propped the milk crate up 3/4 inch with some boards we cut to fit under the crate, so that the lip on the door could slide under the crate and close wo/ issue. We'll ferment this at 50F for a few weeks before moving onto lagering at 40F or so.

Now for the hardest part - waiting for signs of fermentation, which was 3 days with our last lager. Wish us luck! Cheers.

Edit December 15, 2009: We had fermentation going in less than 24 hours, wooo-hooo!

Lager Lag Time & Lessons Learned

We brewed our first Oktoberfest last weekend. It was the first lager we ever brewed - we used the Marzen Madness recipe straight out of Brewing Classic Styles: 80 Winning Recipes Anyone Can Brew. The book recommends pitching cold - at or below the fermentation temperature of 50F. It also recommends pitching *a lot* of yeast, to ensure a clean fermentation with minimal byproducts the are associated with yeast reproducing (like fruity esters and buttery diacetyl). By pitching enough yeast, there is minimal reproducing to do, and the yeast can get down to the business of fermenting sooner.

The Classic Styles book is interesting in that it tells you how many "packs" of yeast to pitch. Lager recipes are all around 4 packs. I'd rather make a starter. I made a 1500ml starter in a 2000ml flask. Once that fermented out, I chilled, poured off the spent wort/beer, and added another 1000ml of fresh wort on top of the little yeast cake still in the flask. The day before brew day paranoia about having enough yeast set in, and I bought another Wyeast 2206 Bavarian lager to be extra sure.

Lesson learned: Since there is little krausen with lager yeast, next time I'll just make two back-to-back 2000L starters.

The night before brew day I put my starter and Activator pack (which I let swell at room temp for a day) in the spare fridge, which I had set at around 48F. On brew day, I cooled the wort down to just below 50F using ice water and a sump pump hooked up to my immersion chiller, much like described towards the bottom of this page. (I suppose I could have let the wort cool in the fridge overnight, but I really like my brew day to be a "day," and not have to aerate again.) After oxygenating the wort to the point the entire top of the carboy was filled with foam (by just trickling the wort through the funnel at the top), we let it settle about 5-10 minutes in the fridge while we cleaned up, then pitched the entire slurry and Activator pack. After a little carboy-shake, back in the fridge it went. I'd say the wort was around 52F, so I set the fridge a little lower to help cool it down below 50F.

The next morning, the fridge was at around 46F, and the temp strip on the carboy was around 48F. No visible signs of fermentation yet. I turned up the temp just a bit, so it was hovering around 52F. Roughly 24 hours after pitching, we had some small signs of krausen. 36 hours later we have this:

The temp is now stabilized around 50F, perfect. Of course, having only brewed ales we are used to seeing the fermenter bubbling like crazy 12-24 hours later. This was certainly a change of pace. I surfed this topic quite a bit, and guys were panicking after a day of no activity. I was ready to wait 3 days until I'd let myself worry about it, since the book said to pitch at around 45F and let it warm up to 50F over the next 2 or 3 days. I didn't pitch quite that low, but did chill it almost that low after pitching. So whatever that means, as long as you get your temps in the ballpark, aerate well, and pitch plenty of yeast... it's time to relax, have a homebrew and be patient!

We'll post a follow-up on how the beer tastes, in like, oh November? Jeez lagers take patience - cheers and good brewing!

UPDATE: Well, it was more like January when we served this, but mighty tasty! Our friends certainly drained it. Just a touch of diacetyl - an issue we're working on.  Going to try doing a diacetyl rest sooner and longer next time.