Help Need (diacetyl)

Hello All!

Been reading all the great posts on the forum for some time now but this is the first time I am reaching out for help. I am a new brewer and have brewed about 6 batches now. With each batch (different recipes) I have brewed there is always a buttery taste to the finished product. With my first batch I thought it was just a case of rushing through the process so on each subsequent batches I made sure to allow plenty of time for fermentation (3-4 weeks) and plenty of time for bottle conditioning (3+ weeks). Each batch has had varying levels but all seem unacceptable to me. It is so bad that each leaves my mouth feeling very slick… I think I am pretty disciplined about about sanitation (use Star San) and making sure to follow directions to the T. I really can’t figure out what I am doing wrong. I have tried using different water supplies (home water vs. water through a filter) and get the same result. I do brew on an electric stove so it can be difficult to get even 1.5 gallons boiling but for the most part it boils for 45 minutes.

Any ideas on what I could be doing wrong? When doing an ice bath I keep the lid on which I thought was a good idea but maybe condensation from the lid is leaking back into the beer. Not really sure where to start but I appreciate any ideas.

Thanks!

Does sound like Diacetyl to me. A week or two ago there was a post to a great link of the scientific explanation of Diacetyl production. I just did a quick search and couldn’t find it again, but maybe someone else can remember the post.
Three things I remember- 1. The biochemical pathway to Diacetyl involves the amino acid Valine. One way to limit Diacetyl production is by having a good supply of Valine. Practical= make sure you have lots of amino acids/proteins available(good quality malts, maybe consider a protein rest in your mash)
2. Overstressed yeast are more likely to produce more Diacetyl. Why are they stressed?- usually not a large enough pitch.
3. Diacetyl is always produced, usually early in the fermentation process(ie. the lag phase). Generally when the yeast are finished with fermenting the simple sugars they turn to their byproducts like Diacetyl (the cleanup phase). The reason when doing lagers we increase the temperature for the ‘Diacetyl Rest’ is to make sure the yeast are still active in order to do their cleanup.
So, not knowing your process, my 3 suggestions are 1. make sure you are using quality malts, 2. Make sure your pitch rates are good, 3. Increase temps late in the process to do a D-rest, and make sure you’re leaving your beer on the yeast for long enough to finish their business.
Well that’s what I remember. Not saying that I may be remembering incorrectly or incompletely, but maybe you’ll get other input. Good luck!

James,

Thanks for the reply and useful information. It is plausible that my yeast are stressed due to under pitching or the fact that I am pitching dry yeast. I only brew 1 gallon batches which always call for adding half the yeast pack which I do but maybe the number of viable yeast in the dry yeast packs is low when only pitching half. Another bit of information… All of my batches have showed signs of fermentation for only a few days. I realize that fermentation is likely still occurring so I have kept in in primary for 3+ weeks but always thought it was strange how quickly it would end. Maybe the yeast is going dominant or dying.

[quote=“indyJr”]James,

Thanks for the reply and useful information. It is plausible that my yeast are stressed due to under pitching or the fact that I am pitching dry yeast. I only brew 1 gallon batches which always call for adding half the yeast pack which I do but maybe the number of viable yeast in the dry yeast packs is low when only pitching half. Another bit of information… All of my batches have showed signs of fermentation for only a few days. I realize that fermentation is likely still occurring so I have kept in in primary for 3+ weeks but always thought it was strange how quickly it would end. Maybe the yeast is going dominant or dying.[/quote]

if youre using 11.5g packets of yeast - a half pack of dry yeast for 1 gallons is overpitching (by a lot).

try pitching less next time. use www.mrmalty.com 's yeast pitching calculator to pitch a correct healthy amount

Oxidation can introduce diacetyl. Have you tried a taste using a thief, selecting a sample from the primary before you transfer for bottling? That might give you an opportunity to narrow down where the problem may be occurring in your brewing process.

How do you transfer your 1 gallon to your bottling bucket?

I usually do taste during the bottling phase and the buttery flavor has been there but not as strong. Seems to be extremely noticeable after bottling. For bottling , I transfer directly from the primary to bottles via an auto siphon with a bottle filler. The auto siphon doesn’t work great so I do find myself pumping the beer into the bottles instead of just priming the auto siphon and letting gravity do the work. Is there a better way to bottle?

If you don’t use a bottling bucket to mix the priming sugar with the beer, how do you carbonate, then?

I use the fizz drops that come with the small batch kit. Basically 1 sugar charge per bottle. The beer is always nicely carbonate but with a really strong off flavor.

Indyjr:
OK, I’m baaaack(My DSL line crashed last night and only now came back up).
So, it looks like you are not underpitching, so that eliminates that . And if you think about it, you know you have plenty of viable yeast at the end because your carbonation is working well.
You also are giving plenty enough time for your yeast to work, so you’re good there.
Next step is to look at your recipes and temperature control. May be something off there.
I’ve only done 5G batches, so can’t say if there is anything off on your 1G batches, but there are more and more posts about 1G batches. Maybe someone has experienced a similar problem.
Reading your latest posts, it does seem that the off flavors are coming during bottling and/or bottle conditioning. What are your bottle cleaning and sanitizing procedures? Some infections can lead to Diacetyl flavors.
It looks like you do have the possibility for some oxidation during bottling. Try moving the container you are bottling from up higher. The autosiphon pump should only need one pump to get it going. You do want as smooth, nonturbulent flow. But to be honest, I would be surprised if you are introducing alot of O2. Could maybe try those O2 absorbing caps.
That’s all I can think of at this point.