Green apple taste in last three brews, not sure how to stop the madness

Hi all,

Long time lurker here, appreciate all the advice on this forum. At my wits end with a green apple taste in my last three brews. Have Google'd this extensively but wanted to see if anyone had any ideas as to what could be causing this.

Last three brews have been a one gallon cream ale partial mash from Northern Brewer, a pumpkin ale 3 gallon BIAB kit from Northern Brewer, and a Left Hand Milk Stout Clone, recipe from this forum, adapted to 2.5 gallons with an increase in flaked oats/barley. All with US-05 yeast. I brew outside for the most part (with the exception of that one gallon kit), pitch at 70-72 F then shake the crap out of the fermenter for aeration. Fermentation takes place under the basement stairs; ambient temperature is 68 F. Ferment for two weeks. Do not take serial FG measurements out of fear of contamination (lame probably I know) but all signs point to fermentation being complete (no krausen, no air lock activity, no bubbles when a flashlight is used to look into the beer). With the cream ale I was in fermenter for two weeks, then bottle for two weeks. With pumpkin ale, fermenter for four weeks, bottle for two. With the stout, I tasted the FG sample I took before bottling and it had a green apple flavor as well. OG on the stout was 1.052, FG today was 1.016. Dont have FG numbers for the pumpkin ale or the cream ale.

Not quite sure what to do. From what Ive read, this is a byproduct of not allowing the yeast to do their thing and clean up the acetaldehyde but you would think 2 weeks would be plenty, which leads me to believe fermentation is getting stuck but not quite sure. The yeast could be strained but I am pitching a full packet of US-05, and 68 should be well within its temp range.

Hope all that helps, appreciate any help you all could provide. Thanks!

 

You've been reading, so you know the green apple flavor is acetaldehyde. That's good.
Why not let your next brew ferment a little longer, try 3 weeks at least with serial gravity measurements to ensure it is done?
You could also take one of your beers, let it sit warm until flat, and check the gravity to see if it is lower than the gravity you bottled it at. If so, the beer wasn't finished fermenting when bottling.
Pitching at 70-72 is a little high, and fermenting at 68 ambient means the beer is probably fermenting at 70-73 during the initial stages. That's too warm. Try cooling it during initial stages of fermentation by putting it in a big tub of cold water with 1-2x 2 liter bottles of frozen water changed out twice a day to keep temps under better control.
Good luck.

 

Are you positive it is a green apple flavor or could it just be beer that is not fully conditioned. Let your cream ale condition for two more weeks at 70° to 74°F, chill for a few days then taste again to see if there is any change.

 

Ferment us05 at the lowest end and even lower and no more green apple

 

Yea, leave it on the yeast cake longer or maybe warm it up a bit after initial fermentation has completed.

 

Last one I had green apple taste in was a NB Nut Brown Ale. I kegged it after 3 weeks, and it was bad.

I read on here that you can add an addition of corn sugar to "wake up the yeast", and let it clean up the brew. So, I just decided to carb the batch in the keg with corn sugar. Added it, let it sit for a couple more weeks at room temp, and when I tapped the keg, the green apple was gone.

After about 8 weeks total, 3 Primary + 2 carbing in Keg + 3 in the kegerator, it turned out to be a very good beer, and it disappeared quickly after that.

 

My neighbor was having a huge problem with acetaldehyde. It took a while to figure it out. Turns out his wife bought him an aeration setup and he was aerating after fermentation was done and right before he kegged! I explained when he should be aerating and the problem stopped!

 

You can't measure a beer's stage of fermentation by sight alone. "Appearance of activity" (both in the airlock and/or ferm vessel) is no indication of when ferm is done, esp. when it comes to yeast clean-up (which you can't see). Consistent FG readings, one after 2 weeks in ferm, then another a couple days later is the only way to know it is really done. You NEED to take FG readings; don't be afraid --- your chances are slim of contaminating your beer at this point. Enough alcohol has formed to ward off any potential airborne intruders/oxidation. Just be careful, clean, and sanitize your sampling equipment, bucket rim and lid each time.

Presuming your yeast is fresh, you're hitting target OG (efficiency/conversion), and your thermometer and hydro are both working correctly, I think your problem is simple: your fermentation is not done. "Green apple" = young beer.

At this point, take another FG, close it up, give the fermenter a gentle slosh and move it to a slightly warmer location for a week. It may re-awaken the yeast and get them to finish up as best they can.

 

As others have stated, acetaldehyde/green apple flavors are deeply associated with young beer. I can't recall if technically the precursors or the acetaldehyde itself is produced during lag/low & high krausen but it is produced to some degree in any fermentation and is cleaned up by living yeast after active ferementation.

The OP said nothing about pitching rates, one of the most important aspects of consistently producing quality results. Acetaldehyde along with being associated with young beer is even more deeply associated with stressed fermentations. Stressing comes in many forms, high ferm. temps & under-pitching being the chief culprits with other things like pH and temp swings during fermentation also occurring. My understanding is that acetaldehyde is actually the byproduct of a poor or stressed fermentation.

If you're pitching enough healthy yeast, is the OP rehydrating the yeast, 2 weeks is enough time to produce a clean moderate gravity beer.

If this were my problem:
I'd chill wort to 65F prior to pitching yeast.
Pitch more yeast than I am currently pitching by 50%(to begin with) and rehydrate properly.
Continue using the space under stairs but implement a swamp-cooler.
Let normal gravity ales sit in primary for 3 weeks then bottle or move it onto fruit, secondary, etc.
Enjoy good beer!

 

You're pitching warm and fermenting warm.

These are two important factors in the production of an array of unwanted fermentation byproducts which will impact a beer's flavor.

Solution.

• Pitch cooler
• Ferment cooler

 

According to one expert, John Palmer, a "green apple" (acetaldehyde) off-flavor is:

"...an intermediate compound in the formation of alcohol. Some yeast strains produce more than others, but generally it's presence indicates that the beer is too young and needs more time to condition."

Now all you have to do is figure out what the connection between this intermediate compound and your process is. A lot of suggestions/solutions offered here, and some of them may be spot-on, but you're going to have to do the research to see what's causing it, and the remedial action to correct it. When you brew your next batch, do everything possible to focus on each step of the process. Write it down. Until such time your brewing routine becomes 'second nature', keep careful records of times, temps, pitching rate, FG/OG, etc.. Your answer may become more obvious than you think.

 

Like Gavin C said pitching and fermenting too warm. If the ambient is 68 F the fermentation can reach as much as 10 F above ambient that could be 78 F (it's an exothermic process...it creates heat). US-05 says ideally ferment range is 59-71.6 F which should be of the wort not ambient temp of the room it is in.

 

I got acetaldehyde I think from using a glass big mouth bubbler for secondary fermentation. The BMB does not have an airtight seal, and secondary fermentation does not produce enough CO2 to keep the oxygen out, so I believe the O2 was seeping through the lid and attacking my beer.

 

I will 3rd the comment about fermenting too warm (unless you are doing a specialty ale of course).

Get a big cube cooler (70qt) and fill with cold tap water (well, 60-65F tap water). Put fermenter in water. Add ice to keep temps on fermometer to about 65-68. Usually only have to add 1 16oz coke bottle of ice 2x per day.

 

If you don't have access to a large cooler then just use a large plastic tote to hold the water/ice bath. I usually can find these at a thrift store for $3-4. Just make sure there are no cracks or holes in the bottom. A large circular one for garden waste is around $6 at your local home improvement store. You can also put a water soaked towel over the top of the fermenting vessel to help keep the temp down.

 

I have to let my beers sit for 4 weeks in the fermenter before they're perfect. Even if I keg at 3 weeks I get a tart/tangy smell and taste. I've never called it acetaldehyde because I've never really thought the taste or smell was "appley" but it's definitely got to be acetaldehyde as it cleans up with that 4th week in the fermenter. 2 weeks is pretty fast, and while some on here can manage grain to glass that fast I'd recommend you to wait another two weeks.


Rev.

 

Hey all,

Thank you all for your replies. It sounds like I should do the following:

1) Be more patient and allow more fermentation time
2) Serial FG measurements (would you do daily or every other day?) to assess the actual end of fermentation
3) Pitch at a lower temp (thought I was being good by getting down to 72F, will get down to 65 for now on)
4) Ferment at a lower temp (short term solution by using a water bath, long term by getting a temp controlled fermentation chamber)

 

1) Not necessarily but won't cause any harm.

2) Not a good idea and not needed. Less you dick with the beer in the FV the better. After two weeks if it's an ale it's likely at terminal gravity. Take a reading and one 3 days later if you feel the need.

Be sure to eliminate measurement error so you don't get false changes in SG readings. (Sample cooled to the correct temperature each time)

3) I'd go lower than 65 if you can for pitching temp and control/monitor the beer temp not ambient. Fermenting beer temperature at 65°F is good for most ale strains and most ales.

4) Good idea

 

I've been having this same problem this season and have been using 05..I always try to pitch in the lower 60 and ferment in low 60 .
I been scared to brew had three bad batches now and boiled off 200 plus gallons since january..think I'll go back to smack packs and start saving yeast again..
Thanks for this post & good luck finding your problem

 

Are you rehydrating the US-05 or sprinkling dry?

 

The off flavors associated with fermening S-05 too cool are usually described as peach like.

 

I've done it both ways but mostly sprinkle dry...I've been hitting my #'s as far as fg I was also thinking I've got problems with my water pH...right now I feel like I'm chasing my tail...I've got got two buckets that need kegged & two that need bottled & scared of dumping more...I do remember my last batch in the spring tasting odd and know for a fact it had 05 in fermenter it was a hopped up wheat....

 

Make one beer, repeatedly, changing only one component to figure out your problem. Different recipes/temperatures/yeast/etc. make it impossible to isolate a problem. You have to master the basics before going all over the place. Pick a simple beer you like to repeat. Maybe smaller batches?:rockin: