I recently got the results of a local homebrew contest back. The category was Blonde Ale. I was a little surprised. All 3 judges had indicated they found various levels of acetaldehyde in my beer. I had noticed a fruit aroma/flavor when drinking it, but it was by no means unpleasant to me. I had actually chalked it up to a component of the yeast. The BJCP style guide calls for a light fruit note to the style so I figured it was expected.
I hate the smell and taste of green apples, so I thought I surely would have noticed the flaw. But 3 judges noticed it so I am not about to argue. I am focused on prevention at this point.
I did a little reading and found 3 consistent causes of acetaldehyde (sanitation, under pitching, pulling the beer off the yeast before its finished cleaning up)
Ill argue sanitation all day. I replace my hoses every few beers and soak everything that comes in contact with the beer post boil in Star San for at least 15-30 min, followed by a scalding hot water rinse.
Under pitching could be it. For this beer, I made a 200 ml starter from a single white labs vial. It went into the flask of aerated starter wort and onto a stir plate. The only change from my usual process was the amount of lead time I gave my starter. I usually give the starter 2 days before brew day. This time, I pitched yeast into the starter Friday night at around 10. I finished brewing and pitched the starter into my wort at 7:30 pm Saturday. So this time it had less than 24 hours lead time. That being said, I still had full krausen in less than 12 hours.
The more I read though, I think I may have pulled the beer to the secondary too soon. I have been brewing the same way for years. 1 week in the primary. Rack to the secondary. One week there. I leave it a little longer if I need to dry hop or if the gravity has not fallen to its expected level. Its almost always given me great results and it fits with my work schedule.
This beer, however, was the first ale I have ever brewed under refrigeration. I kept it at a solid 65F for the first week in primary. I went another week in secondary at 65F. Im wondering if I moved to the secondary before the yeast was done? Ive seen a number of causes for acetaldehyde on various forums. But one comes through with consistency. Acetaldehyde is always produced during fermentation, as an intermediate step of the sugar to ethanol conversion. But in most cases, given enough time on the original yeast bed, the yeast will convert the acetaldehyde into ethanol.
Is it possible that at 65F (about 5-7F lower than my traditional fermenting area), that everything proceded much slower and the yeast did not have enough time to scrub the acetaldehyde?
If anybody needs this info, it was an all grain batch (I can post the grain bill if needed). I used WLP East Coast Ale in a starter as mentioned above.
I hate the smell and taste of green apples, so I thought I surely would have noticed the flaw. But 3 judges noticed it so I am not about to argue. I am focused on prevention at this point.
I did a little reading and found 3 consistent causes of acetaldehyde (sanitation, under pitching, pulling the beer off the yeast before its finished cleaning up)
Ill argue sanitation all day. I replace my hoses every few beers and soak everything that comes in contact with the beer post boil in Star San for at least 15-30 min, followed by a scalding hot water rinse.
Under pitching could be it. For this beer, I made a 200 ml starter from a single white labs vial. It went into the flask of aerated starter wort and onto a stir plate. The only change from my usual process was the amount of lead time I gave my starter. I usually give the starter 2 days before brew day. This time, I pitched yeast into the starter Friday night at around 10. I finished brewing and pitched the starter into my wort at 7:30 pm Saturday. So this time it had less than 24 hours lead time. That being said, I still had full krausen in less than 12 hours.
The more I read though, I think I may have pulled the beer to the secondary too soon. I have been brewing the same way for years. 1 week in the primary. Rack to the secondary. One week there. I leave it a little longer if I need to dry hop or if the gravity has not fallen to its expected level. Its almost always given me great results and it fits with my work schedule.
This beer, however, was the first ale I have ever brewed under refrigeration. I kept it at a solid 65F for the first week in primary. I went another week in secondary at 65F. Im wondering if I moved to the secondary before the yeast was done? Ive seen a number of causes for acetaldehyde on various forums. But one comes through with consistency. Acetaldehyde is always produced during fermentation, as an intermediate step of the sugar to ethanol conversion. But in most cases, given enough time on the original yeast bed, the yeast will convert the acetaldehyde into ethanol.
Is it possible that at 65F (about 5-7F lower than my traditional fermenting area), that everything proceded much slower and the yeast did not have enough time to scrub the acetaldehyde?
If anybody needs this info, it was an all grain batch (I can post the grain bill if needed). I used WLP East Coast Ale in a starter as mentioned above.
