Struggling with Pentainedione

For my understanding Pentainedione is a bi-product of fermentation just like diacetyl, and are somewhat similar.

Any light beer or ale I make seems to suffer from this. It's not a bad buttery sweetness (may be desirable in certain styles). I noticed from my very first extract batch from 3 years ago, to now my all grain setup which is a Kal clone. It wasn't until recently that I really started to notice a similar taste in a lot of my beers. It is characterized by a caramel/honey aroma and initial taste, to a sweet buttery after taste, but its not an in your face buttery like diacetyl is. My friends love the beer and they don't taste bad, but if I attempt to make any light or medium body beer its dominated by this flavor and no matter the grain bill or hops, they taste the same.

I spent some time talking with a local beer club member who studies these things and we are kind of stumped.

Here are some things I do:

I cool the wort to pitching temperatures within 15-20 minutes.
I aerate the wort with pure oxygen and do the purge and shake method which according to a dissolved oxygen meter, gets the oxygen levels to 10ppm which should be plenty for the yeasties.
I just started pitching more aggressive rates, using .75 million cells/ml/degree of plato. Which is more than most of do, thinking my pitching rates were an issue.
I ferment in plastic carboys that always get a good oxy-clean soak for almost 24 hours after use, never used a brush inside them.

I tasted a blonde ale that had a few points of gravity to go and it tasted great, no signs of the issue, a few days later once I hit my FG, I took a sample and sure enough it was dominated by a honey/caramel flavor with that sweet aftertaste.

At this point I can pin point it to fermentation (as evidence by the above statement). Which makes since, since this is a bi-product of fermentation, but, why aren't the yeasties cleaning up after themselves? I usually ferment my ales in the mid 60s sometimes low 60s. I've never struggled with a stuck fermentation or not hitting my FG.

At this point I ordered some Biomat Dar from midwest supplies, which is suppose to suppress the creation of diacetyl and will try that, but its unbelievable to me after going through all of my processes that I am struggling with this.

I also am going to try krausening the blonde ale that I am talking about shortly here. While I'm not using it for carbing, I plan to make a starter with US-05, decant the liquid and pitch the active yeast to see if maybe they can clean up the issue.

I'm hoping that fixes it, but it just makes me wonder why I have to go through all of that to get a clean tasting beer.

Additional note, I mostly struggle with this issue with my ale's and usually use US-05.

Thoughts?

I was just getting ready to post on the forum about something similar. I have just made three batches of beer that all used 2nd generation washed S-05. All of the batches were primaried in the upper 60's for a couple of weeks or more, then crash cooled and kegged.

Each beer had a different grain and hop bill. Each beer has a noticable honey flavor. Blind tasters have commented that I should scale back honey or honey malt when none was used. It is not disagreeable and most everyone liked the beers, but is is not intended.

I suspect the S-05 is the culprit. I have a split batch fermenting one with same S-05 and the other with WLP550. Will post results.

Anyone have other ideas?

I thought you were wrestling with a Greek Goddess. Never mind.

gotsumbeers said:

I suspect the S-05 is the culprit. I have a split batch fermenting one with same S-05 and the other with WLP550. Will post results.

Anyone have other ideas?

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I haven't really thought much about this, only because so many people use US-05 and don't have an issue. But its possible that something about the water chemistry or what have you and the us-05 isn't blending right.

I will be very curious on your results, whats the time line for your fermentation?

It is almost a week in to primary. I plan on having it kegged by the end of the month. I have soft water I run through a charcoal filter and add a little gypsum to my hoppy ales.

We'll see.

Also, I've used S-05 straight from the packet and it is great. Clean and crisp no off flavors. All these beers used the washed yeast, which is still clean and crisp but with a touch of honey.

Pitch cool but try fermenting a little warmer like upper 60's Also, try warming the fermenter into the low to mid 70's as the actions slows down. Warming towards the end will keep the yeast active so they can clean things up.

maida7 said:

Pitch cool but try fermenting a little warmer like upper 60's Also, try warming the fermenter into the low to mid 70's as the actions slows down. Warming towards the end will keep the yeast active so they can clean things up.

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I've looked down this route as well, and even had a few beer ferment in the mid 70s and still get this taste.

It's not diacetyl because the flavor is characterized more by the honey/caramel flavor than the sweet after taste. I'll probably brew another blonde ale and try a different yeast strain like a kolsch yeast or something else.

It's not a bad taste either so I find it hard to believe its oxidation or some other common off flavor. I need to listen to the brew strong episode where they talk about this.

I don't want to try WLP001 since I understand that its basically the same strain as US-05. To be honest there are only few things in common from my first extract days to now they are:

Water
Yeast
Plastic Carboy

I soak all my carboy's overnight with warm pbw and never use a brush inside so I find it hard to think it the carboy. I've never heard of anyone saying the water would cause this and I have excellent brewing water.

At the same time though, I brewed an oktoberfest and used WLP820 and it had some bitter flavor that was somewhat in line with this as well, but different. I took the kegs out of the lager chamber and they have been at room temperature the last month. I'll give it a taste to see what that looks like. I have a hard time comparing that though since its a lager yeast.

I assume you use some sort of sanitizer after you rinse out the PBW...

perhaps it's just your taste buds. Our minds can play tricks on us when it comes to tasting things. I'd have some experienced beer judges taste it. Maybe enter a few comps.

If Pentainedione is a real problem in your beer, I suspect it's related to how you manage the ferment. Reading your OP the first thing I'd change is the temp.

http://www.homebrewersassociation.org/pages/zymurgy/online-extras/oxidation-good-beer-gone-bad

Homebrewers association attributes pentanedione as one of the unfortunate results of oxidation.

dawgmatic said:

http://www.homebrewersassociation.org/pages/zymurgy/online-extras/oxidation-good-beer-gone-bad

Homebrewers association attributes pentanedione as one of the unfortunate results of oxidation.

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It's an interesting read, I'm just having trouble pin pointing if that is happening all the time? If it's happening right as fermentation is winding down then I have no idea how it is. I don't typically expose my beer to oxygen, the only time I can think of that it could get oxidized is when I transfer to a keg and just siphon it in, but I try avoiding splashing.

Further I have trouble thinking this is the issue. I have made some beers that are in a completely closed system and pushing beer with co2 (not my norm) and have witnessed this same off flavor.

What are common areas that people oxidize their beer?

I wasn't thinking oxidation either. I blanket all my transfers with CO2. I'm sure there is some tiny amount of oxidation happening, but my other beers don't suffer from the same flavor. I brew 10gal batches and almost always split it in to two pitches of different yeast. I do everything the same except the yeast. Only the S-05 batches get this honey flavor. Maybe -MG- and I have different problems?

I brewed the blonde ale again last Friday and followed my normal procedures, but added BioMat Dar, which prevents the precursor for Diacetyl from happening. We shall see what this results in. The problem will be going forward is having to rely on biomat to produce a clean beer for me. Maybe at some point I'll try different yeast strains

Sanitized CFC and pumps and tubing with boiling wort 15 min left in boil.
Cooled/Whirlpooled wort to 68 F
Transferred wort to carboy which had a good oxyclean soak and starsan.
Aerated with pure o2 and used a drill with an agiator on it to create a funnel. I did (2) 10 second counts with this method. A dissolved oxygen meter shows this gets me around 10ppm of o2 in wort.
Added 5 drops of BioMat Dar.
Added around 300 billion cells of us-05 (washed yeast)
Ambient temps around the carboy are 64 F and steady. Obviously internal temps are higher, but that shouldn't result in the issue I am having.

Fermentation is going well now.

Just sampled that blonde ale and I'm fairly certain that taste is still there. If it is I'm completely lost. I'm chilling the sample in the fridge because its always more in your face when it's cold.

-MG- said:

Ambient temps around the carboy are 64 F and steady. Obviously internal temps are higher, but that shouldn't result in the issue I am having.

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Why not? I'd recommend pitching cooler in the mid 60's and fermenting where the fermenter can be kept at an internal temp no higher then 70F

Getting the yeast to start the ferment slower may help.

maida7 said:

Why not? I'd recommend pitching cooler in the mid 60's and fermenting where the fermenter can be kept at an internal temp no higher then 70F

Getting the yeast to start the ferment slower may help.

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I mean it could be a factor. I just find it hard to believe I'm that far off on temp to give these flavors. I hear of people fermenting much warmer without issue. Was really hoping the biomat would take care of the issue if it was related to diacetyl, but this makes me wondering if its something else now...

Some people are very sensitive to those flavors. Other people aren't and may never taste it. Also, a blond is a simple clean beer and small flaws will be more obvious.

maida7 said:

Some people are very sensitive to those flavors. Other people aren't and may never taste it. Also, a blond is a simple clean beer and small flaws will be more obvious.

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True. I'm using the blonde ale for this exact reason to test with since nothing can hide in it and this flavor is just over powering any flavor that could be there. Again, its not a bad taste, its hard to describe, but certainly a taste of caramel is in the body of the beer.

-MG- said:

True. I'm using the blonde ale for this exact reason to test with since nothing can hide in it and this flavor is just over powering any flavor that could be there. Again, its not a bad taste, its hard to describe, but certainly a taste of caramel is in the body of the beer.

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Could be kettle carmelization

maida7 said:

Could be kettle carmelization

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not familiar with this. Googling now.

This might be a grasping at straws idea but have you tried changing the brand of base malt you're using? In the lighter beer styles you're obviously going to have a higher percentage of base malt and less of the other flavors that will cover up the base malt's taste. I've never heard if that being the issue but since you've tried just about everything else you might consider it. Signs do seem to point towards a fermentation issue; however, it could be that the residual sugars are keeping the base malt flavor hidden until the yeast finish them off. Ever tried making a blonde ale or similar but mashing in the upper 150s to keep a lot of residual sugars after fermentation is done?

The two beers that are both blonde ales and have this taste were mashed at different temps. One at 147 the other 154.

They did share same base malt. I made a dry stout recently that had no sign of this flavor, but it may be hidden behind the roasted barley.

I'm trying to discover if our first hypothesis is correct that we are dealing with pentainedione. Here are some things we know:

The precursor of diacetyl is alpha-acetolactate and the precursor of 2,3pentanedione is alpha–ketobutyrate.

Pentanedione is said to have a honey like flavor and still with a buttery sweetness in the end. Typically is isn't unpleasant, but not what the brewer intended.

I can't find anything else to references an off flavor like what we have described and we need to circle back to our original hypothesis.

The fact that Biomat Dar did not seem to help the issue isn't a surprise when we look into the precursors for pentanedione. Biomat Dar converts acetolactate in beer into acetoin, but does not mention ketobutyrate, if only I can find a solution for that.

Fermentation temperatures are by ambient room temperature which is very consistent at 64 F. Typically, the warmer the environment, the more VDK precursors will be expelled into the wort. I don't think temperature is the issue, but you never know. I know some people talk about steadily warming up the beer in the final stages of fermentation to help with the clean up process.

I know i can improve the aerating portion of our process. I'll use a diffusion stone and let that go for 60 seconds on pure o2 instead of the purge and shake method. I plan to also use a different yeast strain, most likely that Kolsch yeast I picked up. I may also pressure ferment to ensure a closed system.

Pitching temp is probably the most crucial area in the ferment. Pitch warm and you will produce lots of diacetyl. You can clean up some of that by keeping the yeast active towards the end of the ferment (by warming and swirling) but if you pitched cooler you'd reduce the amounts created in the first place.

Pitch cool to reduce how much is created. The first 24 hours is the most crucial.

Warm towards the end to allow the yeast to clean up any stuff produced during the ferment.

Always look at the actual temp of the fermenting liquid. Do not try to judge fermentation temps by what the ambient air temps are.

-MG- said:

I'm trying to discover if our first hypothesis is correct that we are dealing with pentainedione. Here are some things we know:

The precursor of diacetyl is alpha-acetolactate and the precursor of 2,3pentanedione is alpha–ketobutyrate.

Pentanedione is said to have a honey like flavor and still with a buttery sweetness in the end. Typically is isn't unpleasant, but not what the brewer intended.

I can't find anything else to references an off flavor like what we have described and we need to circle back to our original hypothesis.

The fact that Biomat Dar did not seem to help the issue isn't a surprise when we look into the precursors for pentanedione. Biomat Dar converts acetolactate in beer into acetoin, but does not mention ketobutyrate, if only I can find a solution for that.

Fermentation temperatures are by ambient room temperature which is very consistent at 64 F. Typically, the warmer the environment, the more VDK precursors will be expelled into the wort. I don't think temperature is the issue, but you never know. I know some people talk about steadily warming up the beer in the final stages of fermentation to help with the clean up process.

I know i can improve the aerating portion of our process. I'll use a diffusion stone and let that go for 60 seconds on pure o2 instead of the purge and shake method. I plan to also use a different yeast strain, most likely that Kolsch yeast I picked up. I may also pressure ferment to ensure a closed system.

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I think it would be quite unlikely that your problem is 2,3-pentanedione. First of all, some acetolactate decarboxylase can decarboxylate alpha-acetohydroxybutyrate, the precursor of 2,3-pentanedione (e.g. see here http://aem.asm.org/content/57/10/2796.full.pdf). Second, the flavor threshold of 2,3-pentanedione is about 10 times that of diacetyl, and in fermentations of wort with normal properties (FAN content and amino acid composition) diacetyl and 2,3-pentanedione are produced in similar amounts (usually some more 2,3-pentanedione though), so you would almost certainly detect diacetyl if you detect 2,3-pentanedione.

maida7 said:

Could be kettle carmelization

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That was what I was thinking, possible caramel honey sweetness from maillard reactions during the boil. Make sure your thermometer is calibrated.

Ryush806 said:

This might be a grasping at straws idea but have you tried changing the brand of base malt you're using? In the lighter beer styles you're obviously going to have a higher percentage of base malt and less of the other flavors that will cover up the base malt's taste.

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This, too. Switching your base malt may help.

Since you believe that your problem might also be the yeast strain, why not change the strain and see if you still get the same flavor issue? Do a one gallon test batch with S05 and another with say WLP007.

suregork said:

I think it would be quite unlikely that your problem is 2,3-pentanedione. First of all, some acetolactate decarboxylase can decarboxylate alpha-acetohydroxybutyrate, the precursor of 2,3-pentanedione (e.g. see here http://aem.asm.org/content/57/10/2796.full.pdf). Second, the flavor threshold of 2,3-pentanedione is about 10 times that of diacetyl, and in fermentations of wort with normal properties (FAN content and amino acid composition) diacetyl and 2,3-pentanedione are produced in similar amounts (usually some more 2,3-pentanedione though), so you would almost certainly detect diacetyl if you detect 2,3-pentanedione.

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I have never tasted a diacetyl bomb that people are talking about at times, but the best way to characterize this taste is a caramel/honey aroma with that taste in the body of the beer with a sweet/buttery aftertaste.

That is what I pick up on and two members in the club without telling them what's wrong with the beer picked up on. But based on what you are saying that both are produced in similar quantities and with the flavor threshold being that much higher for pentanedione that the diacetyl should over ride it.

I just struggle to find out what else it could be.

aiptasia said:

That was what I was thinking, possible caramel honey sweetness from maillard reactions during the boil. Make sure your thermometer is calibrated.



This, too. Switching your base malt may help.

Since you believe that your problem might also be the yeast strain, why not change the strain and see if you still get the same flavor issue? Do a one gallon test batch with S05 and another with say WLP007.

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I'll double check my thermometer. I use a Kal clone, exactly like the electric brewery and everything is going to the PIDs. The boils are very rigorous maintaining 212 F and usually have a setting of 85-90% after the boil is going. Would the point here be that its too rigorous of a boil?

I think at this point we need to start deducting possibilities. I'll try making say a 6 gallon batch (I have 20 gallon kettles and hard to make smaller) and I'll split it up into three different batches. One with US-05, one with that kolsch yeast I have, and one with something else, possibly 007. I was also considering WLP001, but its the same strain as US-05, so not sure if we would learn much from that.

The hard part will be getting near identical pitch rates. If I do (3) 2 gallon batches, the liquid yeast will be pitched around 1.5 cell/Ml/Plato, where the dry yeast will be closer to 1.15 cell/ml/Plato. Either way we are easily accomplishing our pitching rate of at least .75 that I try to get. If we are just trying to pay attention to the off flavor we are speaking of, these pitching rates shouldn't matter in any other flavors increased yeast could yield.

Thoughts?

I brewed my blonde ale on friday.

Went to my LHBS and picked up (3) 2 gallon buckets with lids and gave them a good soak of oxi, and sanitized them. Each got just under 2 gallons of wort in it and I choose the follow yeast strains:

US-05
WLP029 (Kolsch)
WLP090 (Super San Diego)

All three are bubbling away at this point. One other item I did different was I used a diffusion stone with pure o2 and get each bucket about a 60 second burst.

The final thing I did slightly different was not boil as vigorously. I was maintaining around 211-212 F and while it wasn't a huge rolling boil like in the past, it was breaking the surface and getting a good mix of the wort.

I'll see how the results come out probably towards the end of the week to see if that taste is still around.