Tag Archives: off-flavor

Off-Flavor: Problem Solved, Hopefully

I am finally quite confident I have identified the source of my problem. The culprit appears to be the malt I bought at a nearby HBS. Given that I crushed and brewed with this grain the day I bought it, it definitely looks like it was bad when I bought it. It was the very fact that it was bad from the day I bought it that made me suspect other things first. That is quite a shame given how much time and beer I’ve wasted.

After I again began to suspect the malt I decided to buy some more fresh, and do a comparison. It wasn’t a perfect apples-to-apples comparison, with the newer malt being Maris Otter and the problem malt US 2-row. But the rest was the exact same: I mashed 60 grams of each in 300mL of the same water for 30 minutes (in the oven), filtered through a fine sieve and then boiled without any hops. I added some yeast slurry I had in the fridge, about 75mL in each flask. I did my best to clean off the residue on the mill, especially given that the only grain I’ve ever used it on had been this questionable malt. I am fairly sure I ended up with some of it in the Maris Otter half, though.

In a comment, Sui Generis mentioned that a time when he brewed with questionable grain it was clear from the beginning that something was wrong. That hadn’t been the case for me before. But this time, both due to having something to compare to and to having no specialty grains or hops to mask the aroma, I noticed the 2-row flask smelled a bit off while boiling, just like what I smelled in the bad beers. This intensified after fermentation began but was obvious even when still.

The Maris Otter half smells very clean in comparison. If I really look for it, I think I detect some of the off smell there, too. But that could be in my head, or it could be due to some residue from the mill. Since the difference is so obvious, I am very confident this malt was the problem. And since my other questionable batches not involving this bag of 2-row did have old, precrushed malt, it’s reasonable to assume the culprit there.

Ultimately, I am glad it was something simple like this. It’s a shame it took several months and lots of frustration to figure it out. I suppose it’s good that I am paying more attention to the water before brewing even though that wasn’t the problem. I do regret having posted that first entry with its bogus deduction. It’s no surprise the problem wasn’t something that exotic. It is surprising how convinced I was this had a plastic character to it, when thinking about it now that’s not at all what it is. Smoky, maybe, but it’s definitely not plastic. I added a note to that post just in case somebody stumbles upon it from a web search or something.

For reference, the bag of malt in question was a 10 lb. bag prepackaged by one of the bigger ingredients distributors (I actually don’t remember which one) that I bought in July. I don’t recall seeing any dates on the package. The HBS has since redone their grain setup completely, so I will probably give them another shot later on.

Hopefully I can now get back to blogging about more interesting things. Thanks to everyone who helped out.

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Off-flavor Follow-up

In my last post on the subject, I mentioned I had just brewed a very light cream ale, a beer in which any of this off-flavor would be immediately noticeable. Sadly, I was right about that! It is quite bad. Like my last post, this is mostly a “brain dump” and thus not quite as coherent as it could be. As always, any help is appreciated.

Given the good quality of the water I brewed this with, I am fairly confident the chlorine or pre-existing chlorophenol hypothesis is out. I do have a few new data points to work with and could instead be looking at oxidation. I had previously discounted it due to the fact the flavor develops almost right away. Generally I’ve seen it stated that it takes a long time for oxidation to show up. But there is a little more this time to suggest it.

At bottling, I noticed none of the specific off-flavor, although there was a bit of acetaldehyde. Out of curiosity I opened the last bottle (only about 3/4ths filled) only two days after bottling. It is already quite carbonated, and it poured with a lot of foam. I immediately got the off-smell and tasted it right away, too. This time I thought maybe I was falsely attributing plastic notes due to reading about such an off-flavor online and my shaky confidence about the water. Although it’s not quite “wet cardboard” or other descriptions of oxidation, there’s perhaps a general staleness to it.

The other half of the 2.5 gallon batch went into a Cubitainer (polypin) with half as much priming sugar. I’ve sampled a few pours despite it being only a little carbonated, and so far there is no real hint of the specific off-flavor or smell there. But there is still that general staleness, I think. So perhaps the carbonation is enhancing my perception of the smell, and perhaps then the smell enhances my perception of the flavor.

That is consistent with past experiences, where I have tasted this during active fermentation or after bottling, but not in the wort or flat beer. Indeed, after taking the bottled beer and pouring it repeatedly between two glasses I started to notice it less and less. So although there’s no reason to think it is a result of overcarbonation or anything like that, it’s probably connected to CO2 as far as my perception is concerned.

There were many opportunities for oxidation in this batch:

  • First, every beer I’ve made from this 10 lb. bag of pale malt has been bad (#3 & #4 from the last post and this one) Although I am crushing it at home and in used it once right when I got home from the LHBS, it’s possible it was old and stale when I bought it. The same goes for the chichas, which were made with pre-crushed malted corn from who knows when, and the first problematic beer which was made with six-month-old precrushed malt. This is supposed to be quite unlikely, but definitely possible. It would be consistent with the smell & flavor being there right from the get-go. However, the malt seems to taste fine raw.
  • Second, in this instance I tried a BIAB, no-sparge mash and let a lot of it drip down from the bag while squeezing it out. Other people have done this many times and report good results, and other beers where I have splashed or dripped a lot (like my popcorn ale and millet saison) had none of this. But hot-side aeration is not impossible, just improbable as far as I can tell so it’s a possibility.
  • Third, and perhaps most damning, I intended to do a short cold crash but ended up effectively doing a month-long lagering since the yeast took forever to drop out. Since it was supposed to be short I replaced the airlock with a piece of foil and a rubber band to avoid suckback. That amount of time with that amount of headspace (half of a 5 gallon Better Bottle) can easily cause oxidation, I think.

Without further experiments I can’t quite discount the possibility that something else is wrong and causing the off-flavor/smell in addition to this beer being oxidized and stale. I can test the malt with side-by-side small mashes with the same water and new malt. I can intentionally splash the heck out of another mash to test that. I am not super keen on wasting a month intentionally oxidizing a beer, but hey, it may be necessary.

This is all quite discouraging, of course, but I intend to figure it out. Thankfully I have had good beers before and in between the bad, so I know it’s not impossible.

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.