Stressing yeast

[Beer-lord]

As I kegged the Coconut IPA today and still taste some alcohol I wondered about what might have gone wrong. I am 100% sure the temps were more than fine so that leaves the yeast.
The 007 yeast I used was from a strain I kept going from last year and I wonder if, while the actual yeast I used wasn't very old, that the original strain from the brewery was already a few generations when I got it and I shouldn't have kept it going as long as I did.
Can't stressed yeast cause some alcohol like flavors too?
Also, I guess I could have overpitched and I think I over oxygenated it.
I think that I think too much and thinking isn't something I'm good at!

[mashani]

Random babbling which may just be nothing more then random babbling but..

How do you think the yeast were "stressed"?

Stressed yeast can throw off more phenols - which might seem spicy or peppery but should not seem like artificial banana flavored nail polish remover? Are you tasting nail polish remover or cheap hooch like flavors, or just peppery spicy flavors?

Underpricing a healthy yeast strain would probably give you the phenols (or esters) but should not really get you fusels. So if your yeast just wasn't that viable then I could see lots of phenols.

If your yeast wasn't just not viable but has gotten mutated to the point where it can still ferment but is using alternate metabolic pathways to do it then normal because the mutation , then it could make all sorts of weird fusels. OR if for some reason it just simply decided to use an alternative pathway more then normal for some other reason, even if it is healthy.

IE for an example off the top of my head - if it uses more of the Ehrlich pathway then a normal fermentation then it could make a lot of different kinds of fusels, some pleasant in small quantities (which might provide a nice aroma in a normal fermentation), some not so much. But usually that would not happen at an offensive level unless there was an greater abundance of available amino acids of the right types then normally found in wort, and I think some sulfur or sulfur containing amino acids. I don't remember all of them your getting into oChem that is fuzzy in my brain... But that mechanism is used commercially in a controlled manner to make all sorts of artificial flavors used in foods.

But coconut potentially has all sorts of amino acids and has small amounts of sulfur. And 1007 is a sulfur producing yeast. So there may be something there.

OR if the yeast you've been saving has gone autolytic, the yeast itself could be a source of the needed amino acids. Like leaving a beer on the trub for 4 months. But this isn't "stressed" yeast, it's messed up yeast.

But like I said this is getting into fuzzy oChem...

[BigPapaG]

Yeah, I agree with mashani... In fact, maybe you are just tasting them too early and they are green.

And I'll say that the most common causes of fusel alcohol production at the homebrew level are:

1. Too high primary fermentation temperature (most common)
2. Too low yeast pitching (this can stress the yeast)
3. Insufficient oxygen dissolved in cold wort (hard to do as the wort aerates some during transfer)
4. Too low pH during fermentation (common in lactic sours and beers with too low of a mash ph)
5. Yeast strain selection (some strains produce more fusls than others)

Normally, fusel alcohols are formed during first stage of fermentation (primary). Top fermenting yeast produce more fusel alcohol than bottom fermenting yeast.

A good sign of fusel presence is an oily film on the top of the wort after fermentation.
Note: This can be difficult to determine in very hoppy beers as hop oils can be present as well!

[Beer-lord]

The things I am very certain of are that the temps were fine. I work very hard to make sure that happens though I am looking into a chest freezer for better summer control.
Based on yeastcalc, I am relatively sure I pitched enough and not too much but as far as oxygen, I used much more than normal.
Then there's the water treatment that I'm very new with.
This is what I get for making a great coconut IPA one time and trying to expect the same luck the second time.

[ScrewyBrewer]

I know trying to describe an off flavor/taste in beer isn't easy but there are a few beers out there that I use to compare the 'alcohol' taste or bite. For me it's Victory Dirt Wolf, it's expensive, high in alcohol but along with the warming sensation I get the alcohol taste too. I'm not a big fan of that beer for that reason.

I'd be interested to know if you made a starter and if so how large was it and how quickly did the krausen rise and fall in the flask? That's my unscientific way of determining the viability of the yeast, if the krausen forms within 6-8 hours and continues to develop vigorously until full krausen then I comfortable knowing I've got some got yeast to work with.

What was the original and final gravity and how long did you let the beer condition?

[philm00x]

Are you only experiencing the alcohol taste with high gravity (1.060+) beers or all beers? My Belgian ales have all had a sort of alcohol burn initially but it all conditions out over several months. The only thing I can think of that you may not have considered is your water and/or pH. You ought to consider what dissolved solids are in your water and possibly also determine if your pH is too low or too high and causing the beer to taste off.

[Beer-lord]

The starter started off rather quickly and I think I used a 2 liter starter (don't have my notes with me at work). It was on the stirplate for 34 hours then I cold crashed it for 24 hours, decanted a good bit of it then added to the fermenter at 65 degree. The krausen did seem to fall faster than normal but the 007 is rather chunky and it does that to me ALL the time.

I brew up to 1.080 and mostly in the 1.065 range and never run into those flavors (except last summer when fermentation did get too hot on 2 beers).
Water is a work in progress though I must say, doing nothing other than Whirlfloc and Campden have always yielded very good results though I'm playing with the water aspect to try to get more of a hop 'pop' as well as aroma out of the hops I use. For the amount I use, I would expect more than I am getting.

[ScrewyBrewer]

I've found that while wlp007 is nice in my brown ales and stouts I no longer care using it in my IPAs. Instead I'm using wlp001 or wyeast1056 and in a pinch Danstar Nottingham because they're very clean fermenting strains that won't muddy up the hop flavors and aromas. Before going digital with my pH readings I had been getting very good hop aroma results using carbon filtered water and a tablespoon of gypsum to 8 gallons of water.