Vexed by Acetaldehyde/Esters

Ingredients
1

I’ve got the brewing version of a hitch in my swing.  With one exception, every time I have ventured into a lighter beer, I have run into moderately strong acetaldehyde/fruity off flavors.  I did manage to brew a Wit last year without them, but now I am wondering if the flavor was masked/integrated into the Wit.  I thought I had my problem diagnosed, but now am forced back to the drawing board.

Last year, I brewed a Cream Ale w/ S-05 and this year a Blonde, also with S-05.  I fermented both cool (low 60s).  While the Blonde is not as sever as the Cream Ale was, both have the same off flavor.  I was blaming my problem on a combination of the S-05 and perhaps too cool of a fermentation, causing the yeast to flocculate before their job was done.  However, I just transferred a CAP fermented with San Fran Lager yeast (WLP810) at 57 degrees to secondary after two weeks and change in primary. I picked up the same problem.  Yes, it’s early for this beer yet, and I’m hoping some conditioning helps, but by now, I know the problem when I see it.  I’m going to try to clean it up by doing a warmer (64) rest before bringing it down to the mid 50s for conditioning.  However, I would really like to nail down the cause of the problem in the first place.  The recent issue with the CAP has eliminated yeast as an option.  That leaves me with just two possibilities: pitch rate and water.

Being in Illinois, I have hard-ish water.  Anything lighter than an Amber, it’s too hard.  So, when I have gone lighter, I get water from one of those drinking water vending machines at the grocery store.  I didn’t think the water could cause this problem, but as it’s the only common thread between the beers, I’m now wondering if it’s part of the problem.

I’m also wondering if my pitch rate and aeration is causing the problem.  I’ve always thought my aeration was o.k.  When I transfer from my boiler, I run the wort through a spray aerator, a strainer, and a funnel into the carboy.  This usually produces enough foam that it’s coming out of the carboy.  I do concede that under-pitch could be a problem.  I would think a rehydrated pack of S-05 would be adequate.  The CAP did have a problem, though.  I had a failure to start from a harvested yeast, so I straight pitched another vial.  While fresh, this is probably not the best.

O.k., that’s the long run-down.  Any insight as to the cause of my problem would be appreciated.  I would hate to be banned from entire categories of styles!  Thanks in advance!

2

How about trying out no secondary, much longer primary, before bottling or kegging?

3

+1!!

4

When you use the vending machine water, is that the only water you use?  Vending machine water is usually RO which means it has practically no minerals and such. Don’t the yeasties need some mineral content in the water to do their job completely?  Instead of using all vending machine water, you may want to try blending it with some of your normal “hard” water so that some of those minerals are present.

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hokerer - That was exactly what I was thinking today.  I’ve never gotten my store water tested, but assumed it to be equivalent to soft drinking water.  Seeing what has been posted in the water profiles thread about this water, I’m now thinking it’s really soft - like <1ppm across the board.  So, yes, with the Cream and Blonde, it was straight store water.  My CAP was 5 gallons store and 3 gallons tap, but like I said 1)the jury is still out on this one and 2)it might have other issues.  Admittedly, I need to study the water issue more, and I know the beers I’m playing with are more difficult.  I’m thinking I might just use my tap next time and add a little citric acid.  Thanks for the help!

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I’m not sure it would be the water. You do want your calicum up around 50ppm to help yeast flocculate but, assuming you are brewing all grain, there should be plenty of nutrients in your beer. If you feel there might not be add a little nutrients, such as WY nutrient or add a piece of copper (such as an IC chiller) during the boil.

How is your fermentation schedule? What temp do you pitch your yeast? Have you tried warming the beer up to the high 60s for a few days after fermentation has finished? Are you in a hurry to transfer the beer off the yeast? 2 weeks should be enough time but if you are having sluggish fermentation then 3 weeks might be better.

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I had an acetylaldehyde problem with a Helles 2 years ago and with a German Pils this year.  The Helles sat at 50F for 4 weeks and had a strong green apple flavor after 2 weeks in the bottle, so I left them at room temperature and they cleaned up nicely after 2 more weeks.  The German Pils had a more mild green apple that was fermented for 2 weeks cold and raised up to 70F for 1 week.  The green apple mostly dissipated, but it was still there in trace amounts.  It could have used a longer warm conditioning rest.

The common thread on both of these beers was that they were each the first pitch of the lager yeast, none of the subsequent batches brewed with the yeast showed an acetylaldehyde problem (even light styles like Dortmunder or Bohemian Pils, or another Helles).  I think you’re more likely to find it in lighter styles and when yeast health is not optimal, maybe certain strains are more prone to producing it.  I have only noticed this in lagers.

Do you rehydrate the dry yeast, and is it within the expiration date?  As others suggested a warm conditioning period will help clean it up as this byproduct needs to be consumed by the yeast, it will not otherwise age out.  I’ve also heard of making a small starter (1 pint) with dry yeast and pitching that into the beer to clean up diacetyl and acetylaldehyde, but haven’t tried it.

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On the yeast pitching, make sure you have enough.  mrmalty.com has Jamil Z’s pitching rate calculator, and that is a great tool to determine the amount you need.

For the yeast nutrients, there are a couple of things to think about with RO water, which I use due to tap water that is only good for very dark beers.

  1. Calcium needs to be in the 50 ppm or greater range as stated.
  2. Magnesium should be in the 10-20 ppm range for yeast health.
  3. Zinc is essential for yeast health.  I use 1/2 of a 15 mg diet suppliment tab for 10 gallons of beer.  Add to the boil in the last 10-15 minutes.

My lagers this year were at final gravity in 5 to 6 days doing the above, at a controlled 50F.  Used to take 2 weeks.

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As some others have said…warming up the beer (70ish) when you are nearing the end of the fermentation stage should help clean up some of the undesirables. The key is to be approximately 60 to 70% attenuated when you begin to warm the beer. Not knowing all of the fine details… it’s really hard to nail down a solid solution.

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This is exactly what happened to me this year (first time doing lagers).  I used one strain all winter and the first batch had some green apple.

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Good insights all, thanks!  My Blonde and Cream were S-05 beers fermented in the low 60s.  In the case of these two, I’m thinking that was just a tad too cool and the yeast dropped out before they finished.  My CAP was with WLP810 (Steam Yeast) @ 57.  This is the one that has me thinking about the water.  The only thing off here was that I know I underpitched.  After a no start on my first pitch from a harvested culture, I bought a fresh vial and straight pitched it.  To try to clean it up, I’ve warmed it up for a few days before bringing it back down.  I hope it works.  My Cream never cleaned up all the way, and the Blonde isn’t off to a good start either.  Maybe I could be wrong in describing my symptoms, but I think it’s pretty clear cut - tastes like a green jolly rancher!

I think for experiments sake, my next lighter beer will be with tap water and a little acid.  Not a bad idea on the nutrient/energizer either.  On the upside, my Cal Common I just opened is MmmMmm goooood!

Thanks again all!