Does water chemistry affect acetaldehyde production?

[goodsuds]

I'm an all grain brewer. I typically brew ales that are 10+ SRM. I filter my water slowly (about 1 gpm) through a KDF filter using a potable water hose from my sink and I add camden to my water to remove chloramines. I know my water chemistry and I use Kai's EZ Water spreadsheet to determine additions to adjust ph; which I usually use CaCl2 and Lactic Acid. I chill my wort to pitching temps with an immersion chiller. I aerate my wort prior to pitching with an aquarium pump and a stone for about 20 minutes and stir/splash the crap out of it. I have temp control for fermentation. I clean my equipment with PBW and sanitize thoroughly with StarSan and I'm meticulous about it. I always flush my kegs with CO2 before I rack my beer.

I never get off flavors in my darker beers, not even in beers at or just over 7 SRM like Pale Ales. But anytime I brew a "lighter" beer (less than 5ish SRM) I get acetaldehyde. It is most definitely green apples, and you can smell it before you even taste the beer. It doesn't matter what the grain bill, which yeast I use, what temps I ferment at, I always get it.

Without getting into details about any particular batch, I'm curious to know if water chemistry can be my problem. I can brew batch after batch of "darker" beer and never get a touch of off flavors. Even cutting my water 50% with distilled still results in acetaldehyde in any lighter colored beers.

Has anyone else experienced this? Should I just stick with RO or distilled water for beers under 7 SRM? Here's my water chemistry info:

Ca ppm - 29
Mg ppm - 11
Na ppm - 30
Cl ppm - 20
SO4 ppm - 90
HCO3 ppm - 29

Thanks.

 

[phendog]

No water expert here. But, brewing a batch using any other water source (store spring water) would rule in/rule out your water as cuprite. May lead you to a course of action on further modifying your RO recipe to where you want it.

 

[dmtaylor]

I'm sure it has nothing to do with water. Acetaldehyde is caused by excessive stress on the yeast, and/or inadequate conditioning at end of fermentation.

What yeast are you using for "lighter" styles? How many gallons do you brew? How much do you pitch? What is your typical fermentation schedule for temperatures and timing? At what point if any do you rack the beer? Do you cold crash, if so at what point?

I think the cause you seek is buried in the answers to these simple questions.

 

[goodsuds]

What yeast are you using for "lighter" styles? How many gallons do you brew? How much do you pitch? What is your typical fermentation schedule for temperatures and timing? At what point if any do you rack the beer? Do you cold crash, if so at what point?

I brew 5 gallon batches. I use Mr. Malty to be sure I pitch sufficient yeast. I keep my yeast in the fridge, including dry yeast. I rehydrate when I use dry yeast. My fermentation schedule and temp depends on the yeast. For example, with US-05/1056 I've found that it's best to pitch around 66*F and let it ferment at 68-70*F. For most other ale strains I keep it in the low to mid 60's. I usually go 3-4 weeks in primary and pull a hydrometer sample and then decide to crash it from there, if I have room.

In April I brewed an amber ale and a cream ale a week apart. I pitched US-05 (rehydrated) in both. Same date code on the sachets. I fermented them both at 68*F. The amber was in primary for 5 weeks and the cream ale for 4 before I crashed them in the fridge for a week and then kegged them on the same day. I purged both kegs with CO2 before I transfered them. I noticed a slight bit of "green" flavor from the cream ale but not the amber. After sitting in the keg at about 37*F, each at 10psi I notice distinct acetaldehyde in the cream ale but not the amber.

I brewed a Pilsner in March with an OG of 1.052. I pitched two (rehydrated) packets of S-23 at 55*F and let it ferment at 58*F b/c that is the temp I've had the best luck with S-23. I cut my water with the Pilsner 50% with distilled water. I let it go for 6 days before I took a hydrometer sample and it was at 1.016 so I let it warm up to 68*F for a D-rest. Time got away from me and it sat at 68*F for 9 days before I put it in the fridge to crash. It was at 1.012 for a couple of days in a row and I tasted no acetaldehyde. Time got away from me again and it sat in the bucket in the fridge for an additional 4 weeks before I was able to keg it. Now I taste apple skin and can smell it.

I know it sounds crazy. I've gone over everything I can think of. I can brew batch after batch of darker beer without any flaws or off flavors but when I brew lighter beers they typically have green apple flavor. That's primarily why I brew 10+ SRM beers.

 

[goodsuds]

The only other thing I can think of is that the absence of dark grains is leading to a lower mash pH that I'm calculating I should be at, and somehow that is stressing the yeast. I don't have a working pH meter any longer and so I've been using these crappy strips that are impossible to read. I guess I need to cough up the money for a good pH meter...

 

[IslandLizard]

Dark grains lower your mash pH. In your case the mash pH could be a little high when omitting dark grains. Higher mash pH is mostly a result of higher alkalinity. Adding a little acid should correct that.

Is your water source stable, mineral wise? 29 ppm HCO3- should be easy to counteract.
Have you tried Bru'nwater just to see if it calculates your mash pH differently?

Could there be another source of acetaldehyde cropping up, aside from possible yeast stress? Looks like your pitching rates are fine. Do you oxygenate/aerate the wort?

 

[goodsuds]

Dark grains lower your mash pH. In your case the mash pH could be a little high when omitting dark grains. Higher mash pH is mostly a result of higher alkalinity. Adding a little acid should correct that.

Is your water source stable, mineral wise? 29 ppm HCO3- should be easy to counteract.
Have you tried Bru'nwater just to see if it calculates your mash pH differently?

Could there be another source of acetaldehyde cropping up, aside from possible yeast stress? Looks like your pitching rates are fine. Do you oxygenate/aerate the wort?

Doh. Yeah, I got it backwards. I forgot darker grains are more acidic.

I just had my water tested again and it only changed slightly so I believe it to be pretty stable, but I'm sure it fluctuates since our primary water source is the Mississippi River.

I don't aerate with oxygen but I do aerate with a stone and an aquarium pump with a hepa filter. I usually aerate for about 20 minutes and stir it intermittently and splash it.

 

[IslandLizard]

Regular aeration like that usually suffices, they're not high gravity beers. Although the grist and water minerals usually provide plenty, maybe try adding a yeast nutrient? Perhaps a critical trace mineral is missing, thus stressing the yeast.

If anything, 4 weeks in a fermentor is a bit long, but I don't see why that would cause the acetaldehyde flavor. Maybe it's in all your beer, just better masked in the darker ones.

I'd brew a light beer with 100% RO and see if that fixes your issue. Maybe it's something in the water.

 

[hottpeper13]

If that is all the calcium you have, it should be increased to at least 50 ppm I like between 70 and 100 ppm. Most of it precipitates out as calcium oxalate,and the rest is used by the yeast,so your yeast could be stressed. I'd kill for your water.

 

[dmtaylor]

I brew 5 gallon batches. I use Mr. Malty to be sure I pitch sufficient yeast. I keep my yeast in the fridge, including dry yeast. I rehydrate when I use dry yeast. My fermentation schedule and temp depends on the yeast. For example, with US-05/1056 I've found that it's best to pitch around 66*F and let it ferment at 68-70*F. For most other ale strains I keep it in the low to mid 60's. I usually go 3-4 weeks in primary and pull a hydrometer sample and then decide to crash it from there, if I have room...

Thanks for the detailed response. It sounds like you are doing everything right! Based on everything you've said, I really don't think there's any stress on the yeast, it sure doesn't sound like it at all. So then now I have to wonder.....

What kind of fermentation vessels do you use? Plastic and rubber components like buckets, hoses, valve internals, etc., can harbor wild beasts which could possibly be more noticeable to you in the flavor and aroma with lighter styles than with dark roasty ones. So yeah... what are your odds of contamination? Maybe you need to replace scratched components that can harbor critters, or maybe just need to replace any plastic or rubber that's any older than about 18-24 months?! Sorry, that's really the only other thing I can think of, as it sure sounds to me like your yeast is happy.

One other suggestion is to have your beer judged by someone certified in the BJCP and see if they can help you troubleshoot. Odds are probably 50/50 that they'll know what the heck they're talking about, but if you know someone or can enter into competitions, their feedback could help you diagnose.

Good luck man.

 

[Dcpcooks]

Acetaldehyde is a byproduct of fermentation and stresses placed on the yeast during fermentation. Common causes are removing the beer from the cake to early. Halting fermentation by dropping the temps to soon. Over oxygenation of wort prior to pitching. Over pitching yeast by improperly estimating pitch size. a bacterial infection. Or oxidation of ethanol after fermentation is complete.

Based on what you've described of your process ( especially the pilsner above) "time got away from me and it sat" I'd start by looking at oxidation after primary is complete. Keep in mind lagers and lighter beers have very clean profiles and off flavors are more perceptible than in darker beers. I doubt it's a water profile thing as Pilsen water is very very clean soft water. It's possible you've got a ph issue but I'd bet money it's oxidation.

 

[goodsuds]

Thank you everyone for your feedback. I think I'll brew another light ale and just use RO water from the store. I think they post their chemistry on their website so I can just make additions as needed to get to the right ratios. If that doesn't work I guess I'll get new buckets and plastic. I just find it odd that that an infection would be it since I use the same equipment to brew a lot of other beers and don't get it. My taste is extremely sensitive to acetaldehyde especially and I've never picked it up in my other beers, and I've never had a BJCP judge say anything about it. I think I'll also try to minimize O2 exposure by kegging it after a couple of weeks so it doesn't sit for as long.

Does anyone know how to possibly fix a beer with acetaldehyde besides krausening it? I took the keg out of the fridge to let it warm up. I read ajdelange talk about using campden to remove it. I'd prefer to do that as a last resort since it's off the yeast cake and I only have whatever yeast is still in suspension to possibly try and fix it.

Thanks.

 

[IslandLizard]

If that is all the calcium you have, it should be increased to at least 50 ppm I like between 70 and 100 ppm. Most of it precipitates out as calcium oxalate,and the rest is used by the yeast,so your yeast could be stressed. I'd kill for your water.

This is actually a really good point.

Add some CaCl2 to your mash water to raise Calcium to 50-70 ppm and increase the Chloride level at the same time. Your Sulfate level is relatively high already (90 ppm), so add no more CaSO4 unless you brew Pale Ales or IPAs (excluding NE IPAs).

Don't forget to include that CaCl2 addition in your mash water calculator, as it will affect your mash pH somewhat.

I wonder which (an)ions are incorrect or missing from your report. The ions don't balance out.

Also, why or how you can smell/taste the acetaldehyde while no-one else does? I hope you're not pointing to the wrong flaw.

 

[goodsuds]

This is actually a really good point.

Add some CaCl2 to your mash water to raise Calcium to 50-70 ppm and increase the Chloride level at the same time. Your Sulfate level is relatively high already (90 ppm), so add no more CaSO4 unless you brew Pale Ales or IPAs (excluding NE IPAs).

Don't forget to include that CaCl2 addition in your mash water calculator, as it will affect your mash pH somewhat.

I wonder which (an)ions are incorrect or missing from your report. The ions don't balance out.

Also, why or how you can smell/taste the acetaldehyde while no-one else does? I hope you're not pointing to the wrong flaw.

My notes from the Pilsner shows that I added 1.6mg of calcium chloride and 2.5ml of lactic acid to my strike water for a chloride:sulfate ratio of just under 1.0.

With regard to the off taste, it isn't that nobody else tastes it, it's just the beers I send to competition don't have it (which all happen to be darker beers). It is an undeniable green apple skin smell (I think the smell is stronger than the taste) in the lighter beers. Other people can smell and taste it and most call it "apple". None of them can pick it out in any of my dark beers, even "dark" beers with simple base malts and mild to moderate hop character.

I'm half tempted to brew something like a Bohemia clone to see what happens.

 

[cobrem]

Could be a bug got into your keg - I recall reading that pedio can cause that flavor as well. Is getting it worse as time goes on? It sounds like you are handling the yeast the right way - not sure what else it could be.

 

[goodsuds]

Could be, but I only get it on light beers and I reuse the kegs batch after batch without issue. Frustrating to try and pin down.

 

[sharpbeer]

Hey, glad I found this post.

I've had this same issue now for the last few months, only on my lighter beers. I use distilled water and adjust salts depending on beersmith water profiles for whatever the specific style calls for. I can smell it and taste it from both of my fermenters, glass carboy and SS conical.

Have you figured out what has been causing this issue?

I'm an all grain brewer. I typically brew ales that are 10+ SRM. I filter my water slowly (about 1 gpm) through a KDF filter using a potable water hose from my sink and I add camden to my water to remove chloramines. I know my water chemistry and I use Kai's EZ Water spreadsheet to determine additions to adjust ph; which I usually use CaCl2 and Lactic Acid. I chill my wort to pitching temps with an immersion chiller. I aerate my wort prior to pitching with an aquarium pump and a stone for about 20 minutes and stir/splash the crap out of it. I have temp control for fermentation. I clean my equipment with PBW and sanitize thoroughly with StarSan and I'm meticulous about it. I always flush my kegs with CO2 before I rack my beer.

I never get off flavors in my darker beers, not even in beers at or just over 7 SRM like Pale Ales. But anytime I brew a "lighter" beer (less than 5ish SRM) I get acetaldehyde. It is most definitely green apples, and you can smell it before you even taste the beer. It doesn't matter what the grain bill, which yeast I use, what temps I ferment at, I always get it.

Without getting into details about any particular batch, I'm curious to know if water chemistry can be my problem. I can brew batch after batch of "darker" beer and never get a touch of off flavors. Even cutting my water 50% with distilled still results in acetaldehyde in any lighter colored beers.

Has anyone else experienced this? Should I just stick with RO or distilled water for beers under 7 SRM? Here's my water chemistry info:

Ca ppm - 29
Mg ppm - 11
Na ppm - 30
Cl ppm - 20
SO4 ppm - 90
HCO3 ppm - 29

Thanks.

 

[sharpbeer]

^^Also, I oxygenate the wort using one of these for about ~5 min. Ferment for 2-3 weeks. Pitch appropriate amount of yeast, use calculator on beersmith, make starters if appropriate. Pitch yeast to wort that is cooled 2-3 degrees below ferm temp, let it ramp up in my fermenter to ferm temp and hold it there.

Perhaps, because I'm using distilled water I'm missing trace minerals that are required by yeast, as IslandLizard has mentioned? I thought the grain would supply that.

https://www.morebeer.com/products/v...o5g96LhY-vCyhNhF8hmGsjDUKUahbYNBoCfkAQAvD_BwE

 

[mabrungard]

If using RO or distilled water, there would definitely be a lack of zinc. I have to think that there could be an effect on acetaldehyde production.

 

[Robert65]

^^^^
Zinc is essential to the function of many enzymes, as well as other aspects of yeast growth and health. And virtually ALL worts, no matter the water source, are deficient in zinc, as most of what might be present is always retained, first, in spent grain, then in trub. Using a nutrient like Servomyces that provides bioavailable zinc, or zinc sulfate or zinc chloride, dosing directly to the fermentor, is always a good idea.

 

[applescrap]

Is it possible that some people are more sensitive to it than others? What hops? Plastic fermenter? Grain type? I have perceived it in mine and others, iirc it fades with time. Little curious what you find. Boil length? Mash lengths? You and I are complete opposite brewers and I have perceived it too in lighter beers. I remember seeing that it was a part of the lager process. Carboy a lager for 4 months and I am pretty sure it wont be there.

 

[mabrungard]

And virtually ALL worts, no matter the water source, are deficient in zinc, as most of what might be present is always retained, first, in spent grain, then in trub.

Rob, I'm not sure that I'd go that far. Many tap water supplies have the trace zinc content that is needed for yeast health. But when using RO or distilled water, the zinc is certainly deficient. Employ something that supplies zinc in that case.

 

[McKnuckle]

This is the first time I'm hearing that now I have to ameliorate my water with a source of zinc.

I brew with distilled water, gypsum, CaCl, acidulated malt, and baking soda when necessary. I make plenty of pale lager and ale styles, and I never have any green apple off flavors, inadequate attenuation, or signs of yeast distress.

I don't doubt your fundamental knowledge on zinc. But are you possibly grasping at straws?

 

[Robert65]

Rob, I'm not sure that I'd go that far. Many tap water supplies have the trace zinc content that is needed for yeast health. But when using RO or distilled water, the zinc is certainly deficient. Employ something that supplies zinc in that case.

Various sources show as little as 5% of the zinc present in malt going into solution and being ultimately available to yeast, with up to 80% of total zinc being chelated or otherwise made unavailable to yeast. (Kunze, Briggs, etc. for references.) So since yeast require between 0.1 and 0.3 ppm depending on the particular yeast, amd as far as I can determine the average drinking water supply contains less than 0.05 ppm, I find it hard to believe that any water supply could be unquestioningly relied upon to provide sufficient zinc. Formerly, trace zinc in copper brewhouse equipment provided a sufficient margin. Today, supplementation is cheap insurance. I myself have noticed a clear improvement in fermentation performance even when using carbon filtered city water.

 

[Robert65]

But are you possibly grasping at straws?

As to whether this is the most likely cause of the acetaldehyde problem in question, I expect that this is indeed grasping at straws. Many more probable causes.

 

[mabrungard]

But are you possibly grasping at straws?

Yes, definitely. That's why the operative word in my post was 'could'. I haven't seen anything definite, but I've also not researched it.

But a condition that stresses yeast could be the cause of acetaldehyde.

 

[sharpbeer]

I believe, I hope*, lack of sufficient levels of zinc in my DI water is what is causing this issue as I've been pulling my hair out over this. I've been brewing on/off for almost 10 years now but just last year got back into it seriously. The beer had been turning out fine until around, I believe, I started using DI water in August to more easily control the salts. The apple taste/smell has occurred in my rye pale, APA, amber ale, and Grodziskie styles, but I was not able to detect it in the two stouts or the NEIPA I have brewed since August with DI water. This week, I have brewed two higher SRM ales, a British best bitter and a wee heavy, hopefully, the acetaldehyde will not be detectable.

I will have to plan a light ale to brew sometime soon and use some yeast nutrient, Wyeast Yeast nutrient or White Labs Servomyces, to test this theory.

 

[foxyoz]

Hey all, how did we go with this- any closer to figuring whether a zinc deficiency was contributing to higher levels of acetaldehyde in finished beer?

 

[porterpounder]

Looking at your process I'd guess that unless you're pressurizing your fermenter after primary fermentation is actively finished (usually 5-7 days) then you're leaving your beer unprotected from oxygen ingress by keeping it in the fermenter for 4 weeks. Darker beers will hold up better to post-ferm oxidation, but the lighter styles would likely suffer from oxidation of the alcohol back into acetaldehyde. I'd start by transferring to a purged vessel for lagering rather than leaving it in primary warm for that 4 weeks. The only other time I've experienced an issue like yours was when our flow-meter on the O2 tank was faulty and we were over-oxygenating the wort on knockout. When we got it back down the acetaldehyde went away.

 

[Vale71]

Without a catalyst spontaneous oxidation of ethylalcohol to acetaldehyde is way too slow to amount to anything. The beer would be so utterly ruined by other oxidative reactions that acetaldehyde levels wouldn't matter in any case.

The issue you were experiencing has to do with excessive oxygen levels being availabe to yeast and causing an increase in acetaldehyde release into the beer.

If the only difference between unaffected and affected batches is wort color I would strongly suspect that this is a different off-flavor being mistaken for acetaldehyde. DMS would be a prime candidate as with modern malts it can only affect beers brewed with extremely light malts.

 

[Franktalk]

I think that some people are more sensitive to acetaldehyde in beer. I think that because I am one of those people. In my light beers, kolsch, light lager, and wit, if I have one, they taste great, no acetaldehyde. When I taste someone else's homebrew, sometimes it hits me right away if it's there. But even in my own light beers, if I have a bunch, I will eventually be overcome with it. I don't usually drink light beers, but once in a while it do because I brew them for my wife and my friends. After 4 or 5 of my really light colored beers I will begin to taste it. Could it be that you are ultra sensitive to it? Do you taste it right away or does it accumulate? Just trying to get to the bottom of it.

 

[sharpbeer]

It's been a few months but I have come with an update.

I am not OP so I am not sure if he and I have the same issue. However, since he has been using distilled water and having this possible acetaldehyde issue, and I started having this issue when switching to DI water, it may be related. Back in February, when I last posted, I had brewed up an English bitter and a wee heavy, both using DI water and added in the appropriate amount of brewing salts per BeerSmith3, both of those beers came out just fine, my wife, friends, and I had not detected anything like in the previous beers. The following month, March, I brewed up a light IPA with DI water+brewing salts+servomyces (zinc yeast nutrient). As the beer fermented it had an acetaldehyde/green apple smell when I nudged the pressure relief valve on my conical fermenter. After pressure transferring the beer to a keg and carbing, when served it still had this green apple smell/taste.

I got tired of tasting apples in all my brews so I gave up on DI water and adjusting water chemistry. I went back to using Chicago tap water since I never had any 'acetaldehyde' issues with it before. Since March, I have brewed up 4 different beers with tap water, 2 light I/APA's, a Belgian Dubbel, and a stout. None of them have had this 'acetaldehyde' issue. I don't know if the culprit was the DI water, (CVS brand, Primo brand, Hinckley brand distilled water), my brewing salts are bad, or whatever other reason, but all of the lighter beer styles I have brewed with DI water since Aug of 2019 (6 different brews) have had this green apple or acetaldehyde smell AND flavor.

 

[sharpbeer]

So, its been 2 years... I'm not sure if this will help anyone in any way but... I just got back into brewing after settling in to our new home. I figured out what my 'acetaldehyde' 'green apple' issue was. It was cascade hops I had left out one day while brewing, they sat and cooked in the summer heat for a good few hours. I then went on and used the rest of these hops in my light ales, which is where I had all these green apple notes.