Can You Explain Off Flavors?

[Mike at Bay]

Ok this is maybe is a dumb question for someone that has brew many kit batches over several years but her it goes.....

Can anyone explain/describe off flavors? I just drink my beers and some I like and some I like better. I often use S-04 yeast, mostly ales (Pale or IPA).

I guess all along I have just assumed the beer was "right" and some were better than others.

Is there a simple explanation?

 

[J A]

There's a simple explanation but not a simple way of describing off flavors, if that makes sense.
Every yeast (and other micro-organisms) metabolize the sugars in the wort and along they way produce by-products in the form of esters and phenols and other stuff that can, in the right concentration, make for flavors that compromise the quality of the beer. Happy yeast usually yields no off flavors. Stressed yeasts can produce some nasty stuff. Infections, even ones that are not too severe, can add some really repulsive aromas and flavors.

The most common flavor that you'll probably run into is acetaldehyde. When your beer tastes "green" and has a slightly harsh "jolly rancher" apple flavor, that's what you're dealing with.
Another would be oxidation. That's a wet cardboard/stale papery aroma and flavor.
Too hot fermentation can lead to fusels and acetates which make for an unpleasant solvent quality.
Too cold fermentation can produce diacetyl that tastes and feels buttery and can be yucky.
A failed fermentation can produce butyric acid and smell like vomit or isovaleric that's cheesy/dirty sock. Other nasties will produce skunk, stable, garbage odors and flavors.
There can be unwanted esters phenols that will produce banana and clove in styles where they're not supposed to be.
There's a ton of information about specific flavor molecules that can show up and what sort of aromas and flavors they produce. Definitely do a quick google survey and find some articles and discussions that you can dig into.
You've almost certainly run into a lot of off flavors but if they're below a certain threshold, you can ignore them and they just seem a little different and not too unpleasant. If you sharpen your palate, you'll learn to pick up on these flavors even when they're subtle and figure out how to avoid them. The result will be a more consistent, higher quality beer.

 

[Mike at Bay]

Wow! Awesome. Thank you. The couple of times I had been concerned that maybe something was "off" the beer was a very hoppy brew that tasted very citrusy or maybe even a little "alcoholy". However, that could have simply been the very hoppy nature or citrusy nature of the recipe. Based on your descriptions the one that fits might be the hot fermentation but it is gone because everyone drank it so.....Cheers! I have been using only dry yeast to this point and have occasionally double pitched when the fermentation stops moving after day 1 or 2. Thanks again I will look into some articles.

 

[J A]

Wow! Awesome. Thank you. The couple of times I had been concerned that maybe something was "off" the beer was a very hoppy brew that tasted very citrusy or maybe even a little "alcoholy". However, that could have simply been the very hoppy nature or citrusy nature of the recipe. Based on your descriptions the one that fits might be the hot fermentation but it is gone because everyone drank it so.....Cheers! I have been using only dry yeast to this point and have occasionally double pitched when the fermentation stops moving after day 1 or 2. Thanks again I will look into some articles.

Our friends always like our beer. It free and they love the novelty of it. I've had a number of beers at small breweries that were straight up bad but they always sold through them. The beer drinking public is not always particularly discerning when it comes to subtleties. A beer has to be pretty awful for someone to send it back or not drink the whole thing.
We have to try to be our own harshest critics and put in some time and energy doing research (drinking good beers for comparison ) and learning as much as possible and talking to other brewers, preferably while sampling beers to compare impressions. If there are any local homebrew clubs or competitions, seek them out. Especially the competitions. You can volunteer and you'll pick up a wealth of information about styles and off flavors.

Here's a pretty good place to start. There are plenty of other sources, as well.

https://www.brewersassociation.org/playlist/off-flavor-management/

 

[Sandy Feet]

Wow! Awesome. Thank you. The couple of times I had been concerned that maybe something was "off" the beer was a very hoppy brew that tasted very citrusy or maybe even a little "alcoholy". However, that could have simply been the very hoppy nature or citrusy nature of the recipe. Based on your descriptions the one that fits might be the hot fermentation but it is gone because everyone drank it so.....Cheers! I have been using only dry yeast to this point and have occasionally double pitched when the fermentation stops moving after day 1 or 2. Thanks again I will look into some articles.

What specific recipes? "Alcoholy" is usually too much simple sugar or something out of balance. Citrusy/hoppy might be your hops. Some American hops (actually, most) are supposed to do that. That is what you want in many American Pale Ales/IPAs. Fruity might be fermenting your S-04 too high. It likes to be just under 68F/ 20C to ferment fairly cleanly. Over 68, you probably are going to get fruity.
If you don't want hoppy, brew a Blonde or maybe more of a malt forward English style and watch the alphas in your hops.

 

[Mike at Bay]

What specific recipes? "Alcoholy" is usually too much simple sugar or something out of balance. Citrusy/hoppy might be your hops. Some American hops (actually, most) are supposed to do that. That is what you want in many American Pale Ales/IPAs. Fruity might be fermenting your S-04 too high. It likes to be just under 68F/ 20C to ferment fairly cleanly. Over 68, you probably are going to get fruity.
If you don't want hoppy, brew a Blonde or maybe more of a malt forward English style and watch the alphas in your hops.

Thanks. I am not sure I can give the best flavor descriptions. I am a fan of hoppy beers....The Alcoholy beer I speak of was a heavy mosaic IPA and my friends drank it all so it might have been my over critical palate tasting my own creation. My fruity one was a Gluten Free beer for my son (sorghum) that had a bunch of lemon and organ peel left in during fermentation....I should have bag those an pulled them at some point. I think I was pretty close to 68F on the S-04 fermentation.....Maybe a degree or so either side of that. Sounds like I could to try and be more careful on the temp control.

 

[Mike at Bay]

Our friends always like our beer. It free and they love the novelty of it. I've had a number of beers at small breweries that were straight up bad but they always sold through them. The beer drinking public is not always particularly discerning when it comes to subtleties. A beer has to be pretty awful for someone to send it back or not drink the whole thing.
We have to try to be our own harshest critics and put in some time and energy doing research (drinking good beers for comparison ) and learning as much as possible and talking to other brewers, preferably while sampling beers to compare impressions. If there are any local homebrew clubs or competitions, seek them out. Especially the competitions. You can volunteer and you'll pick up a wealth of information about styles and off flavors.

Here's a pretty good place to start. There are plenty of other sources, as well.

https://www.brewersassociation.org/playlist/off-flavor-management/

Thanks.....I will!!

 

[Bigbre04]

sensory is a very interesting thing. I have done full sensory training and panels a few times. I can tell you that i do not have the best pallet(sinus issues, deviated septum, etc.).

Some people are extremely sensitive to specific things. One local brewer was obsessed with oxidation and acted like every beer tasted like cardboard when no one else(all brewers, most with sensory experience) tasted it.

as was stated above, getting with local home brew clubs is your real answer. you can buy sensory training kits through morebeer.com. but it is expensive and you really need to do it as a group and follow the instructions on the video below.


This is a whole series on sensory including slides and such. I have done this full course, some of them are very unfun especially when you get up to the upper levels.
https://www.youtube.com/playlist?list=PLNS7LR43RulJK67Q522Nd8Qyh0Ek1vilW

 

[J A]

This is a whole series on sensory including slides and such. I have done this full course, some of them are very unfun especially when you get up to the upper levels.
https://www.youtube.com/playlist?list=PLNS7LR43RulJK67Q522Nd8Qyh0Ek1vilW

Yeah...it doesn't take a lot of some of those molecules to be a pretty big turn off. I find that I have a pretty easy time discerning most off flavors, Not too many really bug me too much when present in low levels but excess geraniol is a drain pour and ethyl acetate in any concentration is a distraction because it reminds me too much of Super Elastic Bubble Plastic when I was a kid.

 

[HighVoltageMan!]

The two most "off " flavors in beer are oxidation and diacetyl (at least to me). Both "off" flavors are sometimes hard to pick up specifically, but they can make the beer taste less than optimal without being "in your face".

Diacetyl is most often described as butter popcorn. But not everyone is sensitive enough to pick up on it, but do notice the beer tastes a little like "homebrew". Oxidation on the other hand can actually take away flavors at lower levels, cause the beer to be bland or sometimes described as "flabby". As the oxidation progresses, the beer can develop a sherry like flavor and if it becomes really bad, the classic cardboard flavor come out. By that time the beer just sucks, as least to me.

It is really difficult to sensory train over a forum. The best thing would be to sit down with an experienced brewer/judge/taster/geek and taste what diacetyl tastes like, it may not taste like butter to you. What does oxidation taste like to you? People often confuse acetaldehyde for ethyl hexanoate. Acetaldehyde tastes like a vegetal green apple and is not a pleasant attribute. Ethyl hexanoate has a bright red apple flavor, which can be pleasant. Most judges (even experienced) taste Budweiser, Coors Banquent or Pabst and say it has acetaldehyde when it's really ethyl hexanoate. In my experience the "off" flavor kits aren't the best, because there may be multiple off flavors coming together to something not included in the kit or the off flavor seems a little artificial when compared to the same flavor in the beer. That aside, it's a good start.

There are a lot of different flavors in beer, some belong in one style and not in another.

The most common source of off flavors are caused by a problem in the fermentation. Low attenuation rates, phenols, high alcohols, ester production (too high or too low), etc. are caused by a problematic fermentation. The better you can identify both the good and bad aspects of your beer, the more accurate you can pinpoint the solution to your troubles.

 

[Bigbre04]

Yeah...it doesn't take a lot of some of those molecules to be a pretty big turn off. I find that I have a pretty easy time discerning most off flavors, Not too many really bug me too much when present in low levels but excess geraniol is a drain pour and ethyl acetate in any concentration is a distraction because it reminds me too much of Super Elastic Bubble Plastic when I was a kid.

butiryic(sp???) acid is rough. so is strong DMS, but the others are not that bad. but as i said, i do not have a great pallet.

 

[J A]

butiryic(sp???) acid is rough. so is strong DMS, but the others are not that bad. but as i said, i do not have a great pallet.

Yeah...nobody like butyric. There are some expressions of it, though, when it's assimilated by certain yeasts that give an interesting pineapple flavor. Just the right amount and strain of wild yeast or brett can be interesting. Personally, I don't like those styles enough to seek them out and I don't want to find it in any of my brews.
I've just never had to deal with any DMS, though I have had some crazy aromas from it with good floor-malted Czech Pilsner. It drives off fast but I start heating for boil with the lid on to get things going faster and that first lift of the lid can give a nose-full of somewhat nauseating corn and cabbage. I don't think I've ever really noticed it with other Pilsners or 2-Row malts and I've never dealt with it in a finished beer.
Diacetyl is one that I don't have a lot of tolerance for. I've had some nice expressions of it in a Golden/Brown Ale with S-04 fermented low. It combined with the malt to give really nice butterscotch/toffee notes, though even when it's good, it's a little cloying.

 

[Sandy Feet]

Thanks. I am not sure I can give the best flavor descriptions. I am a fan of hoppy beers....The Alcoholy beer I speak of was a heavy mosaic IPA and my friends drank it all so it might have been my over critical palate tasting my own creation. My fruity one was a Gluten Free beer for my son (sorghum) that had a bunch of lemon and organ peel left in during fermentation....I should have bag those an pulled them at some point. I think I was pretty close to 68F on the S-04 fermentation.....Maybe a degree or so either side of that. Sounds like I could to try and be more careful on the temp control.

Mosaic is awesome if you use it for late additions. I made a somewhat New England style with a White Labs Hazy liquid yeast that was all late addition Cascade and Mosaic, and it turned out very well. The alphas in that hop are massive. You would have to be very careful going early.
Do you have the recipe for the Mosaic one you didn't like?

 

[Bigbre04]

Yeah...nobody like butyric. There are some expressions of it, though, when it's assimilated by certain yeasts that give an interesting pineapple flavor. Just the right amount and strain of wild yeast or brett can be interesting. Personally, I don't like those styles enough to seek them out and I don't want to find it in any of my brews.

Woof. That is one of the primary reasons that i dislike true kettle sours. between the barnyard and the puke funk i just cant stomach them. also fond memories of opening the Mash mixer after a few days at 85f and admiring the fuzzy white layer. the best part was that you could see where the flies/bugs had walked across the top of the white fuzz...fucking gnarly.

I've just never had to deal with any DMS, though I have had some crazy aromas from it with good floor-malted Czech Pilsner. It drives off fast but I start heating for boil with the lid on to get things going faster and that first lift of the lid can give a nose-full of somewhat nauseating corn and cabbage. I don't think I've ever really noticed it with other Pilsners or 2-Row malts and I've never dealt with it in a finished beer.

ya dms is fairly uncommon in to get, but when it is dosed in a bottle toward the heavy end of the tasting range it is unpleasant to say the least.

Diacetyl is one that I don't have a lot of tolerance for. I've had some nice expressions of it in a Golden/Brown Ale with S-04 fermented low. It combined with the malt to give really nice butterscotch/toffee notes, though even when it's good, it's a little cloying.

its common and acceptable in some english styles. at low amounts in a beer where i expect it, it is pleasant. I have actually found that it is a common flavor that i get from dirty draft lines. There is a sports bar in town that i always forget not to get draft from. Draft Yuengling is one of my favorites at the bar, but damn, i always get the butter bomb from the draft line at this one bar. Gross.

i actually ran into some serious off flavors when we were on vacation in kentucky. large brewery out there that everything that we tried had some form of grossness, both cans and bottles. sucks, because they were the only damn thing that most bars where we were had besides domestics.

 

[J A]

i actually ran into some serious off flavors when we were on vacation in kentucky. large brewery out there that everything that we tried had some form of grossness, both cans and bottles. sucks, because they were the only damn thing that most bars where we were had besides domestics.

I don't know how those places stay in business. I guess they don't, eventually, but they seem to hang on despite what's plainly not well-brewed beer. There's usually pizza and a big open area with a playscape involved in the equation.

Woof. That is one of the primary reasons that i dislike true kettle sours. between the barnyard and the puke funk i just cant stomach them. also fond memories of opening the Mash mixer after a few days at 85f and admiring the fuzzy white layer. the best part was that you could see where the flies/bugs had walked across the top of the white fuzz...fucking gnarly.

Whenever I brew I'll throw the spent grain in the city compost bin. Overnight that stuff gets pretty horrible and if I brew on Tuesday or Wednesday and it sits until the next pickup on Monday, it's frigggin' putrid!

 

[Donoroto]

I find it easy to demonstrate DMS odor, in the steam about 10-15 minutes into the boil. Cooked or creamed corn is a typical description.

Light Strike damage is also easy, get a (clear glass) bottle of Miller or Heineken and leave it in the sun several minutes, a bit warm, and ‘skunk’ will be obvious. But to me, it’s not like the animal skunk, but more like skunk cabbage, which is a weed that has very large leaves and grows in swampy or boggy areas. Break the stems to get the odor.

The rest of them, to me, are a bit more subtle and a lot harder to demonstrate.

 

[Minbari]

Sure it has been covered, but the simplest explanation. Off flavors are flavors that aren't supposed to be there.

It can be a defect of the style or an actual defect.

Like DMS or high clove is generally a defect, but In a beer with a high corn content or a hefe these are desirable.

So depends on the intent and what the defect is