Dealing with an Off-Flavor

Please note: I have since discovered the problem seems to be something completely different. While chlorine in brewing is definitely a problem, this whole post should be taken with a grain of salt.

I’ve now had four batches ruined by a nasty, smoky plastic off-flavor that is first noticeable shortly after fermentation begins. This is commonly attributed to chlorine in the water, something I have always treated. Tracking down the cause has thus been difficult, especially since there is pretty much nothing I did or used brewing these that I didn’t elsewhere without problems:

  1. Pale ale, 5 gallons, March 2012
    • Hagerstown, MD tap water w/ 1/2 Campden tablet in 10 gallons
    • Rahr 2-row, English crystal 60L, wheat malt
  2. Chicha de jora, 2 gallons, May 2013
    • Washington, DC tap through PB-1 carbon filter (~6 months old)
    • Peruvian maiz jora (malted purple corn)
  3. Pale ale (different from #1), 1 gallon, July 2013
    • Washington, DC tap with 1/4 Campden tablet in 5 gallons
    • Briess 2-row, Briess crystal 20L
  4. Chicha (different from #2), 1 gallon, October 2013
    • Washington, DC tap through Watts carbon filter (~2 months old) and treated with a full Campden tablet in 5 gallons
    • Briess 2-row, maiz jora

I didn’t slouch, as far as I can tell, in removing chloramine from the water. I made many batches using carbon-filtered water without further treatment, and made two good beers using raw tap water with Campden for dechlorination. Batches 2-4 didn’t make it to bottling, but #1 did and I used Brita water to make the sugar solution. Up until #3 I also did not treat the water used to make the sanitizer, either StarSan or iodophor. With #4 I used distilled water to mix the StarSan. Since this still didn’t solve it, I was about ready to give up on water as a factor.

I’ve considered a few other potential contributing factors. I was able to eliminate contamination as a possibility through saving unfermented wort, sterilizing it and carefully pitching yeast on two of these batches. Both times I got the off-flavor, even using other yeast strains. I thought also about oxidation, either in the mash or in the grains themselves since some of these were pre-crushed and a little old. But that theory fell apart with batch #3, which used malt I bought that day and crushed 30 minutes before mash-in. Plus, as far as I can tell the plastic flavor points in the direction of phenols, not oxidation. Cleaning products and such were also fine as far as I could tell, and saving the wort as mentioned above also helped eliminate some of those variables. As for equipment, batch #1 shared only a copper immersion chiller with the other three, as I wasn’t brewing at home.

I was at just about my wit’s end with this when I got a new bit of info. Reading AJ DeLange’s HBD article about dechlorination, I found out that chlorophenols can form in the water supply itself. Phenols are abundant in nature, and can react with chlorine at the water treatment plant just as it would in your beer. In that case, dechlorinating the water doesn’t do any good since the chlorophenols are already formed–assuming, of course, that I understood the article correctly.

In retrospect, for at least batches #3 and #4, the water had a bit of an earthy taste. I’ve noticed that a lot here after rainstorms. Even through the filter the taste was there. I don’t remember what the water for #1 or #2 tasted like, so I can’t say for sure this is related to the problem (not that I could if I did, anyway). But, at least, it’s something to go on.

I have to do a lot more testing, but it could be an issue of bad upstream water quality, and in the case of filters I could have run the water too quickly. With too high a flow rate the water may not be spending enough time in contact with the carbon. AJ and many other brewers are unequivocal about carbon filters’ efficacy in removing chloramine, despite some claims to the contrary, but the rate is definitely a factor. The removal of other undesirable compounds is also affected. So, it sounds like the way to go for me is slow filtration, and perhaps getting a chlorine test kit to verify effectiveness.

I made another batch this weekend, a light cream ale in which any such off flavor will be obvious. I ran water through the filter very slowly. It was clean and had no off taste or smell. The 2-row malt was the same as in #3 and #4. To sample without disturbing the main batch, I separately fermented sterilized leftover wort as I’ve done before, and so far it is clean. I’m just hoping that holds true.


100% Popcorn Malt Ale – Tasting

100% Popcorn AleMy excitement about this beer, which was probably very evident from my original post on it, was tamed a bit when I went to bottle and measured the FG. After correction, it was about 1.001. What was supposed to be a 4% ABV beer turned into about 5.3%, and with such a low FG I feared it would be very thin and/or a little boozy.

I would imagine this low FG is due to the extended mash, specifically the ill-advised extra 1 hour rest with fresh amylase at 63C/145F as was recommended in the instructions for the amylase formula. This particular amylase formula has beta-amylase, but being of fungal or bacterial origin I wasn’t (and still am not) sure it has the same temperature range as grain amylase. So, I went with the optimal temperature given, which in retrospect probably meant the optimal temperature for converting all starch and dextrins into fermentable sugar.

Fortunately, it looks like it wasn’t that big of a problem. Notes follow.

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100% Malted Popcorn Ale

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It’s time for something a little different and not really yeast-related. I recently decided to try home malting again after two unsuccessful previous attempts. The BYO article earlier this year provided the inspiration as well as the missing information I needed to do it easily and correctly. After a successful, though undermodified, batch of wheat malt, I decided to repeat my first experiment: malting run-of-the-mill popcorn from the grocery store. I did this two years ago, before I started brewing at all, so I knew very little about how it worked in practice and ended up throwing it out before I did anything with it.

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DCY02 & DCY03: DCambic Isolates

DCY02 and 03 Fermentation in Progress

I am happy to report that isolating the yeasts from The Mad Fermentationist’s DCambic was a success. I have written about it previously and had some issues at first. A lot of stuff going on in life then kept me from the project for a few months but eventually I got the time to get it going again. I have been posting off and on about it on Twitter, but it’s time I document it here.

The key to success the second time was growing a liquid culture first from a sample Mike gave me, rather than plating it straight from the sample. After a few step-up culture iterations I was able to isolate four different yeasts from the beer, instead of just the one I got the first plating attempt. Two were useless for brewing: one is possibly Rhodotorula and the other is another yeast that does not ferment. The others were almost certainly Brettanomyces.

I can tell them apart on a plate because one (DCY02) grows white colonies and the other (03) tan colonies. Liquid cultures are also markedly different: DCY02 forms a pellicle very quickly, smells very funky and drops out fairly quickly, whereas DCY03 takes much longer to form a thinner pellicle, smells very fruity and drops out a lot slower. Taste profiles from the starter are along the same lines as the smell.

I made two simple extract beers in April (1.040 of pilsner DME) and the picture above is of fermentation about two weeks in. They were slow to start but that may be due to low pitching rates. In any case, I have not yet bottled these as they seemed to reactivate after I moved in late May. Perhaps just shaking them a bit roused enough yeast into suspension to do something, and I want to make sure they’re done before I bottle. (I will update this once they are done.)

Strain Descriptions

DCY02: The “white” isolate, based on colony appearance. This has a funkier Brett character with less of the fruity qualities. It produces a pellicle very quickly, and during fermentation produces a thick foam cap that looks more like Sherry flor than ale yeast kräusen. It dropped out of suspension faster than DCY03.

DCY03: The “tan” isolate. This is significantly less funky, and a lot fruitier. It doesn’t produce much foaming during fermentation, and in fact may appear to be doing nothing at all. If shaken, though, there will be a lot of CO2 released. It did not produce a pellicle until several months after pitching and left the wort cloudy for about a month.


I hope to have more details soon, both from my beers but also from those of a few brewers I sent samples to. This was also the first time I’ve distributed anything so I kept it limited to four people. However, in the future I will release larger amounts to whomever wants it for a small fee to cover shipping and materials. Future announcements will be made on the blog and on Twitter.

PSA: Monitor your Yeast Bank

Much to my horror, recent attempts to revive four(!) different banked yeasts from my library have been unsuccessful. I fortunately have “backups” of the ones I consider most important, the “DCY” yeasts (which reminds me that I need to post an update about the DCambic yeasts, which are still fermenting one half-gallon each) and was able to work from that. But what I had considered my primary source of the two DCambic strains appears to be totally dead after just a few months.

I made a switch about six months ago to banking in isotonic NaCl solution after reading Samuel’s post on the matter. My previous attempts at reviving strains have succeeded, even with vials that were a few months older at the time. So, I’m suspecting operator error at this point and am very unwilling to cast this as a fault of the method. After all, Samuel used it for a while, and this is not a novel method. Possible problems include:

  • Improper solution: I used sea salt, because I couldn’t find a pure salt without additives. A lot contain minute amounts of dextrose, and I was trying to limit any sort of metabolism. Due to unknown levels of other salts in the mix it could require a different amount to be isotonic. I could also just have measured it wrong.
  • Storage temperatures at the back of the fridge were too low. Perhaps they dipped into freezing at times, and the small volume cooled off quickly.
  • I just moved a few weeks ago and somehow they got damaged in transit. Not likely, I don’t think, since I just moved within the same building and they were back in the fridge in just minutes.
  • Or, perhaps, I simply killed the sample while transferring into the salt solution. I had already revised my transfer method to avoid shocking yeast with a hot loop but it’s still a possibility.

The other two attempts were from slants. I have not had any issues in the past even with old slants, but these two for whatever reason opened slightly in storage and the tape around the cap wasn’t enough to hold the air in. They dried out as a result. I have successfully recovered yeast from such a slant before, but I am not so lucky this time–not yet, at least. As a last-ditch effort I will add sterile wort directly to the slant vial instead of picking off with a loop.

In either case, though, this highlights the need for monitoring things and perhaps something as simple as periodically tightening the caps on my vials. I may switch back to slants, at least temporarily, while I figure out what could be going wrong with the salt solution method.

Update: I was able to wake the two slanted strains up from their dead, dried, reddish state by adding sterile wort directly to the slant and shaking vigorously throughout the evening. In addition to having dried off, they were also slanted on media I made very early on that wasn’t ideal. I am surprised, frankly, that I was able to do this.

Update #2: Correcting update #1, it looks like only one of the slants actually yielded live yeast. As for the two DCambic yeasts from the NaCl storage medium, colonies finally are visible a week after plating. This is not unusual for Brettanomyces left at 20-22C/68-72F so this may have been much ado about nothing.

Baking with SD Isolate

Bread made with SD yeast isolate

I finally got around to doing something I’ve wanted to do since the beginning: bake bread leavened with the yeast isolated from a sourdough culture. A few days before baking I started growing a starter of sorts. I did three steps up from a very small amount of yeast stored in isotonic salt solution. This is similar to what I do for beer but I stopped at about 200mL of weak broth (can’t remember if it was YEPM or MYPG; I forgot to label the jar when I made it). Once I had enough and it had settled I used a sterile pipette to suck up the sediment from the bottom, about 6 grams’ worth of loose, liquid sediment for a 500g dough. It rose overnight in the upper 60’s with a proof of about four hours the next morning. The tiny amount of yeast is in line with what I’d use with dry baker’s yeast for a long rise–it’s probably equivalent to a sixteenth of a teaspoon or so of active dry yeast. The dough is just flour, water, salt and yeast.

I figured it’d not be worthy of a post because it’d probably turn out exactly like a bread made with standard baker’s yeast. After all, it’s just yeast, with no lactic acid bacteria to create the sourness. To a great extent that is true, but the neat thing is that this yeast apparently produces a ton of diacetyl. I had noticed this before when using the sourdough culture it came from (my wheat starter) but I had for some reason assumed it was bacteria doing it. But when I took it out of the proofing basket today I got a massive whiff of butter. This made for a quite nice aroma while baking, although it seems to have completely disappeared in aroma and taste by the time the bread cooled.

These yeasts were the fastest growing (at least in terms of visible colonies) that I’ve seen so far. I suppose that’s consistent with what you’d expect from a continuously-refreshed culture like sourdough, but that’s just speculation. I have no idea what species they are, but I’m fairly certain it’s not S. cerevisiae based on the quick growth and colony characteristics. The colonies spread out much more than I’ve seen with S. cerevisiae. They are also whiter and flatter. I keep meaning to ferment wort with it to see its alcohol tolerance and sugar utilization but never get around to it.

Sourdough Plating #3 and DCambic Update

This is the third and final attempt at plating out the whole sourdough starter. I did a few things differently:

  • I fed the three sourdough starters and let them ferment for 12 hours before starting. Last time two of the starters were right out of the fridge.
  • I put even less of each culture in the sterile water to dilute it
  • I used bromocresol green + potato dextrose plates, plus one potato lactose plate

The rye starter’s plate grew mold in a few days. It totally took over before I had a chance to see anything else growing. The other two starter’s plates plus the lactose plate (on which I plated the wheat starter) were totally fine. I let them grow out for 16 days.

Clockwise from top left: brown rice flour starter, wheat flour starter, wheat starter on potato lactose plate

The colonies look translucent and shiny from certain lighting angles, but they are off-white, smooth and round and actually matte. I did not see any flat colonies like last time. The weirdest surprise is the almost identical growth on the lactose plate. I am going to assume that this is due to whatever sugar was in the potato and not the lactose. My goal in doing so was to see if I could get the bacteria to grow on there and was not expecting the yeast to grow at all. You can see very tiny colonies on each of the plates between the large yeast colonies and smaller yeast colonies. They are transparent and shiny. I believe these are the lactic bacteria.

I think I may not have used enough bromocresol green, or the plates were old enough that it had already started to fade. I was expecting green colonies here, too, but they were white. On my first (recent) attempt I did see green colonies but the plates were also darker back then. The colonies looked quite similar between the two starters. This is a change from the first time I did this (earlier in the year) but could be because I am using a different medium.

I picked out a yeast colony from each and plated it on YEPM medium (recipe from jaapie’s site; the ingredients are not cheap or easy to find for hobbyists like me). In the past, the yeast I isolated from the wheat starter didn’t appear to ferment maltose whereas the rice starter’s did. We’ll see if these grow on it (from what I can tell, yeasts generally but not always can grow on something they can ferment and vice-versa).

On another note, I finally resumed the DCambic project from April. I had isolated a yeast from it back then but it appeared to not do much besides make lots of strong fruit esters. Notably, it didn’t seem to produce any alcohol. This time I instead went for growing it in liquid first instead of plating directly from the sample. I now seem to have two different types of yeast in liquid, judging from the two colors of sediment I see. A darker sediment formed first. I then started shaking to aerate the culture on a regular basis for a few days and then added this to more sterile wort, which I similarly shake on a regular basis. I am now seeing a lighter color sediment forming as well. I also see lots of evidence of fermentation, though I did not see any krausen at any point. I shook up the culture yesterday and streaked a sample on a PDA plate. I’m hopeful that this time I can get the yeast that produces the distinct Bretty aroma I can smell from the culture.