I'm doing everything right (right?)...But still can't get rid of yeast off-flavors.

[Near-Beer-Engineer]

I've taken all the steps. Tried all the techniques. Bought all the equipment... But I still get a slight (subtle, but noticeable), off-flavor from my yeast in pale/light beers.

I've been brewing all-grain for years and have made some great beers (including some medal winners) - but the issue of creating completely clean, neutral beers continues to elude me. The "yeast" flavor I'm referring to here is very subtle, and I can only describe it as a slightly cloying "fruitiness" (although fruitiness isn't entirely accurate, it is difficult to put a finger on) that I assume are some esters generated during fermentation. This ester hypothesis was confirmed when I did an experiment that split the wort into 2 batches: one batch was fermented in a SS keg pressurized to 15psi and held at room temperature, the other batch was fermented "normally" in a plastic brew bucket but held at proper fermentation temperatures. Pressurized fermentation is supposed to suppress ester and fusel alcohol production, even at elevated temps. The pressurized batch was completely clean and crisp, while the normal batch had the yeasty off-flavors.

This experiment was on a Blonde Ale. Both batches (pressure fermented vs normal) use the same wort from the same kettle. Below is the recipe and the steps I took:

Yeast Baby Blonde Ale (5.5gal):

• Malt:
  • Pale 2-row - 11lbs (91%)
  • Crystal 10 - 0.5lbs (4%)
  • Acidulated Malt - 5.6oz (3%)
  • Vienna Malt - 2.4oz (1%)
• Hops:
  • East Kent Goldings 5%AA - 1oz - 60min
• Yeast
  • Escarpment Labs American Ale (American Ale)
  • Described as a clean, neutral yeast. I believe this is similar to Wyeast 1056.
• Specs:
  • OG: 1.048
  • FG: 1.003 (alarmingly low... but confirmed with multiple hydrometer readings on both the pressure and non-pressure ferments)
  • IBU: 19
  • SRM: 5
• General Process:
  • Built ~9gal of soft water profile using distilled H20 (more details below). Mashed at 149F for 60min. Batch sparged with 170F water. Boiled for 60min. Cooled to 65F. Aerated and pitched yeast (from starter). Fermented at 64F for normal batch (room temp for pressurized batch) until FG was stable, about 7 days.

Steps I Took To Make Clean Beer:

1. Yeast Starter - made an adequate starter (1.6L @ 1.038, on stir plate) based on the Brewer's Friend calculator. Cold crashed and decanted the starter liquid prior to pitching.
2. Water Chemistry - built the water from scratch using about 9gal of distilled H20 and adding 2.7g CaSO4, 5.4g CaCl2, 1.05g MgSO4 and 0.9g NaCl. Also used acidulated malt to keep pH in check.
3. Yeast Nutrient - added 1/2tsp to the kettle @ 5min
4. Vigorous boil - very vigorous for 60min, no lid
5. Cooled rapidly - cooled to 65F with an immersion chiller right after the boil
6. Sanitized (obviously) - everything was cleaned with PBW and sanitized with starsan
7. Aeration - transfer from the kettle to fermenter is "loud" i.e. it comes out of the spigot and drops about 4 feet through the air into the fermenter, creating lots of splashing and foam. Fermenter is then shook by hand afterwards.
8. Controlled Temperature - fermentation of the "normal" batch was held steady on the cooler end of the recommended range at 64F (17.8C) in a temp controlled fridge. Note, the pressure fermented batch wasn't temp controlled at all and turned out much cleaner.
9. Clean transfers - transfers to kegs were done via autosyphon into kegs thoroughly purged with CO2.

Nice to see that pressure fermentation has some good effects; however, how do I get that clean flavor without using pressure? Do I need to ferment even cooler? Or am I missing something completely?

Any thoughts are much appreciated!

 

[FunkedOut]

give lager temps and yeast a try

 

[Miraculix]

Use another yeast. Have you tried us05? probably the most used ale yeast, for a reason.

 

[McMullan]

How long was the beer sat on the yeast in the primary? It might be worth transferring to a secondary before packaging, if you think you might be sensitive to these yeast flavours. I know I am. It's possible too that you've underpitched and given the yeast a more stressful job to complete. Maybe try to repitch a shed load of healthy, freshly harvested yeast. That's two useful experiments to do.

 

[Panderson1]

Is that the only yeast you have ever tried? 've never heard of it tbh. Everything you typed sounds good tho. Have you tried a starsan purge prior to kegging? Are you cold crashing? That can bring oxygen into play. But a blonde ale should be OK

 

[Near-Beer-Engineer]

How long was the beer sat on the yeast in the primary? It might be worth transferring to a secondary before packaging, if you think you might be sensitive to these yeast flavours. I know I am. It's possible too that you've underpitched and given the yeast a more stressful job to complete. Maybe try to repitch a shed load of healthy, freshly harvested yeast. That's two useful experiments to do.

The beer was on the yeast cake for no more than a week. I've also tried gelatine fining the off-flavor batch to remove as much yeast from the beer as I can, but the flavour persists.

You may be on to something with the underpitching, although I did make a good starter using healthy yeast. The pressure-fermented batch had a lower volume of liquid, and the yeast slurry was just eyeballed into both batches. It may be that the pressure batch got proportionally more yeast.

Is that the only yeast you have ever tried? 've never heard of it tbh. Everything you typed sounds good tho. Have you tried a starsan purge prior to kegging? Are you cold crashing? That can bring oxygen into play. But a blonde ale should be OK

I've also used Wyeast 1056 as well as another liquid strain years ago that I can't recall. No cold crash on these, and the kegs were starsan purged first with CO2.

If my process is looking good, then it may just be an intricacy of these particular yeasts. Switching yeasts as others have mentioned, or changing ferm temps (lower?) might be necessary.

 

[spittiz]

Just a thought - have you tried varying the fermentation temp within the optimal range? With US-05 for instance, many find that fermenting below 18 C gives fruity esters.

 

[McMullan]

The beer was on the yeast cake for no more than a week. I've also tried gelatine fining the off-flavor batch to remove as much yeast from the beer as I can, but the flavour persists.

You may be on to something with the underpitching, although I did make a good starter using healthy yeast. The pressure-fermented batch had a lower volume of liquid, and the yeast slurry was just eyeballed into both batches. It may be that the pressure batch got proportionally more yeast.




I've also used Wyeast 1056 as well as another liquid strain years ago that I can't recall. No cold crash on these, and the kegs were starsan purged first with CO2.

If my process is looking good, then it may just be an intricacy of these particular yeasts. Switching yeasts as others have mentioned, or changing ferm temps (lower?) might be necessary.

I found 'over pitching' freshly harvested yeast tamed things, to an extent comparable to my favourite commercial ales. What I do now is pitch the starter into a half batch, to get a beer and harvest more than enough fresh yeast to repitch. Then harvest and repitch at least a few times. Not the only factor, but a fundamental one, IME. We just can't buy yeast like it, it has to be harvested and repitched fresh. Give it a go. I think it's likely to solve at least a lot of the perceived issue. Let us know how it goes

 

[Drewch]

Maybe try a batch with dry yeast like US-05, S-04, or BRY-97 ... or even Saflager 34/70. I've found 34/70 tastes cleaner at ale temps than US-05 --- it's kinda become my favorite clean "ale" yeast .

 

[Miraculix]

Maybe try a batch with dry yeast like US-05, S-04, or BRY-97 ... or even Saflager 34/70. I've found 34/70 tastes cleaner at ale temps than US-05 --- it's kinda become my favorite clean "ale" yeast .

Same for me! If it just would not be so powdery...

 

[Near-Beer-Engineer]

give lager temps and yeast a try

Use another yeast. Have you tried us05? probably the most used ale yeast, for a reason.

Maybe try a batch with dry yeast like US-05, S-04, or BRY-97 ... or even Saflager 34/70. I've found 34/70 tastes cleaner at ale temps than US-05 --- it's kinda become my favorite clean "ale" yeast .

I have an irrational aversion to dry yeasts... but you're probably right as US-05 or similar is worth a try. Lager yeast could work as well I'm sure, but would take longer and require lower temps. I'm just perplexed how some people get great clean beer using American Ale strains. Maybe it's mostly a perception thing.

 

[marc1]

Was the 64F temp the beer temp or the chamber temp?

 

[Near-Beer-Engineer]

Was the 64F temp the beer temp or the chamber temp?

Temp was measured with the probe taped to the outside of the brew bucket with foiled foam tape.

 

[marc1]

Sounds like you just might not like that yeast much. Fortunately there are many to choose from.

 

[Drewch]

Lager yeast could work as well I'm sure, but would take longer and require lower temps.

If you're not looking for the mystical Weihenstephaner lager crispness, you can totally run W-34/70 at ale temps (upper 60s °F / 18-20°C), and it'll finish in ale times (7 - 14 days depending on OG). The best stout I ever made was with W-34/70.

 

[Red over White]

"Nice to see that pressure fermentation has some good effects; however, how do I get that clean flavor without using pressure? Do I need to ferment even cooler? Or am I missing something completely?"

I have a couple thoughts on this. If you want to emulate pressure results with an airlock with your chosen yeast strain you probably need to dial in your coldside work. Temperature, pitchrate and 02 levels at pitch will influence this. You need to really know what makes your strain tick.

First WAG is your very fermentable wort profile is lending to ester and fusel production early with your strain that isn't as apparent under pressure.

It's a long way to the top, if you want to rock n roll!

 

[kevin58]

The beer was on the yeast cake for no more than a week. I've also tried gelatine fining the off-flavor batch to remove as much yeast from the beer as I can, but the flavour persists.

I'm thinking its possible you didn't leave it in the fermenter long enough. There is some yeast action that happens after active fermentation that helps clean up compounds that contribute to unwanted flavors.

 

[Beermeister32]

give lager temps and yeast a try

Agree. Time to buy a fermenting refrigerator and begin producing lagers. My favorite is WLP833 German Bock yeast. I pitch at 46F, ferment at 50F.

 

[Bobby_M]

The beer that was in the plastic bucket could possibly be slightly oxidized. The one unintentional variable in the split test is that the pressurized keg was certainly more air tight than the bucket. When light oxidation occurs, it generally strips hop character first which can come across as a cloying sweetness long before it starts tasting stale or cardboardy.

One week on the yeast is actually a little too short in my opinion. Taking the beer off the yeast too soon can leave Diacetyl and Acetaldehyde behind. Maybe you already know what both of those taste like and the yeasty taste you describe generally has nothing to do with either. If you're not quite sure what they taste like, do some more reading on both. Diacetyl can make for a cloying flavor because we associate it with butterscotch in some cases. Acetaldehyde is more of a tart green apple, jolly rancher candy so for some people it comes across as an apple ester. I get raw pumpkin flesh and latex paint.

 

[dmtaylor]

Chico yeasts (US-05, 1056, WLP001, etc.) are not as "clean" as everybody makes them out to be. They're slightly fruity. If lager is what you really want, then use a lager yeast. I recommend Diamond or S-189, or if liquid is your preference then how about 2206, 2308, WLP830, WLP833, etc. You can try fermenting these at warmer temperatures in the 60s F, you'll likely find they are pretty darn clean at these temperatures, regardless of advisement to the contrary. I am continuing to experiment with warm-temp lager ferments, with good success so far, been very very pleased.

 

[FunkedOut]

Agree. Time to buy a fermenting refrigerator and begin producing lagers. My favorite is WLP833 German Bock yeast. I pitch at 46F, ferment at 50F.

Same here! Pitch at 46*F and ferment on a 2 week ramp from 48*F to 54*F.