Strange off flavor developed in Brown Ale???

[bignick270]

This weekend I went to make the first pour from my keg of a brown ale and it had the strangest flavor. At first it was sort of vanilla like but the more I tried it, maybe it was a butterscotch like flavor. I read that Diacetyl can have a butter or butterscotch flavor but it is odd since I am using Safale US-05. For this beer, I fermented on the cooler side at 64 but that should be within the temperature range of the yeast. In the past usually run US-05 around 68 to 70. If it is Diacetyl, then I guess I should have done Diacetyl rest by raising the temp on the last day. This beer was in the fermenter for about two weeks while I was setting up my kegerator. The off flavor was not enjoyable at all and I ended up tossing the batch (luckily I am just doing 1.5G to 2G batches).

I decided to try my second beer last night which is a Pumpkin Stout. I think there is a very slight butterscotch off flavor, but it is masked by the pumpkin pie spices. This beer was fermented with the same temperature profile as the brown ale, but was in the fermenter for about a week. This beer was in a different keg.

I ferment in a 5 cu. Ft chest freezer with a BrewPi setup where the beer temperature is read from a sensor inside a thermowell that is placed in the beer. The beer temperature usually only swings +/- 1 degree.

Also, the beer line is new and I ran BLC and water through the line before use. While dumping the keg, I tasted it and the flavor was definitely in the beer and not from the draft system. Unfortunately I did not taste the sample when I transferred it to the keg.

Any ideas? I have not encountered this flavor during the past 3 years or or so of brewing.

 

[TexasDroughtBrewery]

The only thing that comes to mind is let it age a little longer, a week isn't a lot of time...

 

[ba-brewer]

Supposedly diacetyl can leave a slick feeling to your mouth, so if you are getting a slick feeling it could be diacetyl. If it is diacetyl it can be from an infection and not have to come from the primary yeast used to ferment the beer.

It does not hurt to bump the temp a few degrees toward the end of fermentation to help the yeast to finish strong and do some clean up. You want to bump the temp before the yeast slows down too much, so like after 3 or 4 days of activity.

I think oxidation can come across as a carmelly like flavor in the beginning before the cardboard/sherry flavors set in.

 

[bignick270]

There could be a chance that the yeast was slightly under pitched and may have been stressed. Since this was a 1.5G batch I pitched a half pack of Safale US-05 (rehydrated). Half a pack should have had a high enough cell count but who knows depending on the viability of the yeast.

My beer from this past weekend was pitched with a full pack of US-05 for a 2G batch and I am running it at my normal fermenting temperature profile. Also I am replacing my siphon hose just to make sure it’s not an infection issue. In reality I have had my siphon hose for a long time, probably longer than I should have had it.

Oxidation could have happen. I am using 5G kegs for these small batches. This was the first small batch beer I have ran through my keg (before I relocated, I was doing 5G batches). I thought I purged the keg pretty good but it may not have been enough.

 

[ba-brewer]

I think you had enough yeast, i use half a pack of s-05 for 3gal average gravity beers. S-05 can get estery at lower temps, but that should come across as fruity/peachy and I dont think you were cold enough for that.

Take a look at this thread, to get the oxygen down to a minimal level it takes like 7 or 8 purge and pressurize cycles, maybe more depending on the pressure, that is a lot of CO2 if you do not have a full keg. You might want to looking into some of the smaller kegs if you want to do more smaller batches.

https://www.homebrewtalk.com/showthread.php?t=565834

Replacing plastic stuff like racking canes and tubing periodically is cheap insurance.

 

[bignick270]

I hate to resurrect this thread but I am still getting the off flavor...

Since this post in February I did several more beers, all dumped due to this off flavor, including this brown ale, a pumpkin stout, and an IPA. I then shut things down for a while while moving and getting the new brew area setup. Anyway I just brewed a 2.5G APA and low and behold the flavor is back.

All plastics have been replaced (transfer tubing, beverage tubing, c02 tubing). All metal has been cleaned and broken down (posts, faucets, vslves). I am using new C02 with a different tank. I use star-san and PBW and everything was rinsed well. I also use 2.5G ball lock kegs (added after my first failed beer). My APA tasted fine out of the fermenter and I did a mostly closed transfer to my keg (but ran into technical difficulties). I placed C02 on the keg for a week and sampled it two days ago and it was okay but not ready. Last night I sampled it again and all hop flavor was lost and this off flavor came through.

This is very odd because it always happens while in the serving keg and after being on c02 for 1 week. At 2 weeks it becomes very pronounced and undrinkable. My sample last night was also weird. The first sip was mostly beer from the serving line and it tasted decent with hops. it was until I filled the glass and tasted the beer pulled from the keg that I lost hop aroma and picked up the flavor.

I have a hard time trying to describe the flavor, nothing I think really matches the common off flavor descriptions. My wife, who doesn't drink, thought it was kind of cidery or sweet but I did not get that. It could be astringent but I have not tasted sherry to compare.

Two things come to mind.
1) Astringent flavors. For the past year I have been doing BIAB and I have been doing a fine mill to get high efficiencies. I read that overmilled grains can cause Tannins to be released during the mash. My issue with this is my mill gap is the same as my few batches prior to kegging when I bottled and they were fine.
2) Oxidation. I am picking up oxygen during the transfer to the keg, or while it is in the keezer. I can do better about purging. I tend not to purge prior to transferring, only purging after the transfer. My other thought is that my ball lock disconnects are tough to secure on the post and I might have a small leak on the gas post. Could this cause oxygen intake?

I just put a pumpkin milk stout on c02 2 days ago so I hope it is not a failed batch either but the way things are going who knows.


I brewed for almost 3 years prior to this happening and did not have an issue with bottles or kegging so this is extremely expensive and discouraging.

 

[Smellyglove]

You're picking up a descriptor of Diacetyl, while your wife picked up "cidery"

I'd look into where you might be picking up an infection. Which parts in the line did you not replace?

Since you've been brewing for three years, I guess you know what you're doing, so it seems like it might be something external, like a mellow infection. They can cause the diacetyly-thing you said you're picking up in the first post, and also make beers taste "cidery". Even if you didn't pick up "cider", your wife did, and a beer isn't supposed to taste like cider.

 

[Devin]

Are you aerating your wort before pitching the yeast? Does your fermentation usually start fairly quickly, or does it sit for a while before starting? Palmer states that long lag times early in fermentation can produce excessive diacetyl. I actually experienced that once when I forgot to aerate before pitching.

 

[bignick270]

So i am unsure if it is diacetyl at this point, it was a guess early on back in February.

All hoses have been replaced. In fact the entire brewing process is different and in a new location. Early this year I was in a kitchen of an apartment brewing on a stove top with my ferm chamber in the bedroom. Now I am in a garage with an electric brewing setup and I am now fermenting in my old 5G corny kegs.

I probably did not aerate this batch and I probably did not aerate my pumpkin milk stout enough either but it seems fermentation kicks off pretty quick (at least by looking at bubbles since I am in a keg).

 

[Horseflesh]

What yeast are you using in these brews? A variety?

A leaky keg will not introduce oxygen as long as the keg stays pressurized.

I think tannins come not from mechanical sources like crush and squeezing, but pH problems. Do you know what your mash/sparge pH is?

 

[bignick270]

Mostly Safale US-05. I also did a Hefeweizen with a liquid hefe yeast (that also messed up).

I did not monitor mash PH on these brews with the exception of the most recent pumpkin milk stout which was 5.2.

Just to thow this out there, my water has been a mix across these brews. I started with store bought spring water. I then tried RO with brewing salts, and now the last two batches are using filtered well water (no water report yet).

 

[ba-brewer]

I hate to resurrect this thread but I am still getting the off flavor...

2) Oxidation. I am picking up oxygen during the transfer to the keg, or while it is in the keezer. I can do better about purging. I tend not to purge prior to transferring, only purging after the transfer. My other thought is that my ball lock disconnects are tough to secure on the post and I might have a small leak on the gas post. Could this cause oxygen intake?

I brewed for almost 3 years prior to this happening and did not have an issue with bottles or kegging so this is extremely expensive and discouraging.

If you had a leak on your gas post I would think you would drain your tank faster than normal. Also as long as gas is escaping it would prevent oxygen from entering.

I don't pre purge my kegs before filling, but do purge the head space afterwards. For me I don't think I have issues with oxidation from that process.

Maybe the next time you brew bottle up a portion to see they develop that off flavor. You can just add priming sugar in the bottle and fill a few. If the bottle version develop the off flavor it is happening before kegging.

 

[bignick270]

Unrelated issue but very embarrassing... I just figured out I have been placing the gas disconnects on the post designed for liquid disconnects. I did not know they were keyed. I just thought I had cheap disconnects that would not latch . When I brewed before my kegging setup was pin lock but I switched to ball lock when I got the 2.5G kegs,

On to the real information...

I drew a pint tonight and it was extremely hazy so I tossed it because it looked like I was picking up pure sediment. I drew another pint and it was closer to a hazy APA. So far it seems like the off flavor is not present in this second pint. I am trying to sample it as the glass warms to see if it changes. It would be crazy that I dumped those previous beers because I was pulling yeast sediment off the bottom of the keg.

I will keep this thread going if something changes. I also think my next couple of batches will be simple smash style ales so I can refine my process.

 

[ba-brewer]

Unrelated issue but very embarrassing... I just figured out I have been placing the gas disconnects on the post designed for liquid disconnects. I did not know they were keyed. I just thought I had cheap disconnects that would not latch . When I brewed before my kegging setup was pin lock but I switched to ball lock when I got the 2.5G kegs,

On to the real information...

I drew a pint tonight and it was extremely hazy so I tossed it because it looked like I was picking up pure sediment. I drew another pint and it was closer to a hazy APA. So far it seems like the off flavor is not present in this second pint. I am trying to sample it as the glass warms to see if it changes. It would be crazy that I dumped those previous beers because I was pulling yeast sediment off the bottom of the keg.

I will keep this thread going if something changes. I also think my next couple of batches will be simple smash style ales so I can refine my process.

In my kegs the gas in dip tube does not reach the beer, does your keg have too long dip tubes?

 

[bignick270]

sorry for the confusion. The dip tubes are correct but I have swapped the posts (part that the disconnects attach to) when assembling the units after cleaning.

The post for GAS should have notches in the base while the LIQUID post does not.