52 replies to this topic

[No Party JKor]

How do they differ? When should they be done? What temp rise is ideal/good?Anyone?

[djinkc]

No idea if it is even necessary with ales. It was done by default here since I usually had 6-8 kegs waiting their turn for the kegerator at around 70df. I added another chest freezer for cold conditioning and carbing recently so stuff doesn't sit for weeks before it goes in the kegerator. I'll be surprised if it is an issue since lagers are rare around here. I did keg a pseudo pils recently feremented cold with wyeast 2112. It went straight into the conditioning/carb freezer. Tasted fine to me at that point so I don't think a D-rest was needed. The ales that have gone with this new routine also tasted fine to me. Guess time will tell.

Edited by dj in kc, 18 July 2010 - 07:09 PM.

[Mya]

No idea if it is even necessary with ales. It was done by default here since I usually had 6-8 kegs waiting their turn for the kegerator at around 70df. I added another chest freezer for cold conditioning and carbing recently so stuff doesn't sit for weeks before it goes in the kegerator. I'll be surprised if it is an issue since lagers are rare around here. I did keg a pseudo pils recently feremented cold with wyeast 2112. It went straight into the conditioning/carb freezer. Tasted fine to me at that point so I don't think a D-rest was needed. The ales that have gone with this new routine also tasted fine to me. Guess time will tell.

one I am aware of is Ringwood ala WY1187, or WLP005, I am presently fermenting a Special bitter with WLP005 and plan on doing the last 3 days of a 2 week primary @70f to clean up diacytl

[davelew]

How do they differ? When should they be done? What temp rise is ideal/good?Anyone?

A properly fermented beer (ale or lager) made with fresh yeast should not require a diacetyl rest. My suggestion is to taste a beer, and see if it tastes like cheap buttered popcorn. If so, you may need to re-visit your yeast handling in future batches, and you can save your current batch with a D-rest.Diacetyl rests are done by pro brewers in order to use lower quality yeast. Diacetyl is typically produced by metabolic mutants after many generations of yeast propagation, and fresh yeast from Wyeast or White Labs or any reputable supplier won't throw diacetyl for the first couple of beers you make with it.

[chuck_d]

Here's a formula from Heyse, pp 184-186, to calculate how long a d-rest needs to be.Days of diacetyl rest required = (100 - SUM(avg. daily ferment temp *C)) / Diacetyl Rest Temp *CSo like 3 days of primary at 18*C and a d-rest at the same temp(100 - (18+18+18)) / 18 = 2.5 daysor say you have a lager with a more complex fermentation profile(100 - (6+7+7+8+9+8+7+6)) / 6 = 7 daysI'll dig up some more info on the different kinds of fermentation profiles you might see for you and post back.

[Big Nake]

If I make a lager, I do a d-rest. Period. My method is simple... allow primary fermentation to get to (or close to) completion and then just take the primary out of my 50° space and leave it on my cool basement floor for 1-2 days. In the winter, that my be upper 50s, lower 60s and warmer than that in the summer. After that, I send it to secondary. It's easy and even though it's not required for all strains, I do it anyway to be safe. Some ale strains clearly state that a d-rest may be required (Wyeast 1968 London ESB comes to mind). That particular strain has some other issues including premature floccing which requires rousing the yeast and since it's so flocculant and low-attenuating, I like the d-rest in the equation to make sure the beer isn't underattenuated. Cheers.

[ThroatwobblerMangrove]

If I make a lager, I do a d-rest. Period. My method is simple... allow primary fermentation to get to (or close to) completion and then just take the primary out of my 50° space and leave it on my cool basement floor for 1-2 days. In the winter, that my be upper 50s, lower 60s and warmer than that in the summer. After that, I send it to secondary. It's easy and even though it's not required for all strains, I do it anyway to be safe. Some ale strains clearly state that a d-rest may be required (Wyeast 1968 London ESB comes to mind). That particular strain has some other issues including premature floccing which requires rousing the yeast and since it's so flocculant and low-attenuating, I like the d-rest in the equation to make sure the beer isn't underattenuated. Cheers.

+1

[davelew]

Has anyone actually had a problem in homebrew with too much diacetyl? My experience is that when I do a D-rest too early my lagers taste a litte "ale-like", and when I skip the D-rest I never have any problems.

[ThroatwobblerMangrove]

Has anyone actually had a problem in homebrew with too much diacetyl? My experience is that when I do a D-rest too early my lagers taste a litte "ale-like", and when I skip the D-rest I never have any problems.

I've only made 3 lagers and I d-rested all of them. I did however do the d-rests pretty late so I didn't get much ale like qualities. I've been using 2308 which is notorious for diacetyl so that's why I've been doing them.

[davelew]

I've only made 3 lagers and I d-rested all of them. I did however do the d-rests pretty late so I didn't get much ale like qualities. I've been using 2308 which is notorious for diacetyl so that's why I've been doing them.

I d-rested my first few lagers as well, up until a more experienced brewer convinced me that if you pitch enough yeast into an all-barley wort, d-rests are unnecessary. Here's the explanation I've heard:Diacetyl is produced from this pathwayProtein deficient wort --> Yeast cells need to synthesize the amino acids valine, leucine, and/or isoleucine --> Yeast cells piss out alpha acetolactate as a byproduct of amino acid synthesis --> alpha acetolactate outside the yeast cells is spontaneously oxidized into diacetyl.So, three things need to happen for diacetyl to be a problem. First, you need to have a wort where there's a lot of yeast growth, and the new yeast cells need a lot of protein, which in general means that you underpitched. Second, you need a wort without enough proteins. Barley is relatively high in protein, corn and rice are not. So if you put a lot of adjuncts into your beers, you might have one precursor to a diacetyl problem. Third, you need to have oxygen in your beer at the end of fermentation. Since hop acids tend to preferentially oxidize before alpha acetolactate, this means you need to have a low-hopped beer.Basically, diacetyl is only likely to be a problem if you're brewing a Miller Lite clone where you underpitch (so a lot of new yeast cells need to be synthesized) AND use a lot of adjuncts (so there's a protein deficiency) AND add very few hops (so there's still oxygen in the beer).

[ThroatwobblerMangrove]

I d-rested my first few lagers as well, up until a more experienced brewer convinced me that if you pitch enough yeast into an all-barley wort, d-rests are unnecessary. Here's the explanation I've heard:Diacetyl is produced from this pathwayProtein deficient wort --> Yeast cells need to synthesize the amino acids valine, leucine, and/or isoleucine --> Yeast cells piss out alpha acetolactate as a byproduct of amino acid synthesis --> alpha acetolactate outside the yeast cells is spontaneously oxidized into diacetyl.So, three things need to happen for diacetyl to be a problem. First, you need to have a wort where there's a lot of yeast growth, and the new yeast cells need a lot of protein, which in general means that you underpitched. Second, you need a wort without enough proteins. Barley is relatively high in protein, corn and rice are not. So if you put a lot of adjuncts into your beers, you might have one precursor to a diacetyl problem. Third, you need to have oxygen in your beer at the end of fermentation. Since hop acids tend to preferentially oxidize before alpha acetolactate, this means you need to have a low-hopped beer.Basically, diacetyl is only likely to be a problem if you're brewing a Miller Lite clone where you underpitch (so a lot of new yeast cells need to be synthesized) AND use a lot of adjuncts (so there's a protein deficiency) AND add very few hops (so there's still oxygen in the beer).

If the question of diacetyl production is just what you mentioned above why are certain yeast labeled as diacetyl producers?

[davelew]

If the question of diacetyl production is just what you mentioned above why are certain yeast labeled as diacetyl producers?

I don't know -- that's why I asked about homebrewers with diacetyl problems. I only know of two groups of homebrewers:(1) Homebrewers who do diacetyl rests, and have never had a diacetyl problem(2) Homebrewers who do not do diacetyl rests, and have never had a diacetyl problemI'm curious to know if there's a third group, people who don't do diacetyl rests and who HAVE had problems. My hypothesis is that people do diacetyl rests because pro brewers at Bud, Miller and Coors do those rests, and that the rests aren't actually necessary for homebrew.edit: I don't know about the "diacetyl producer" label of some yeasts, but I've also found that the attenuation numbers for different yeasts are among the least important factors in attenuation, so diacetyl might fall into the same category.

[MtnBrewer]

I've judged beers with diacetyl problems so it's not a figment of our imagination. Some yeasts just tend to throw diacetyl: 1084, 1187, 2308 maybe others. It can also be caused by contamination and as you pointed out, poor fermentation dynamics.

[davelew]

I've judged beers with diacetyl problems so it's not a figment of our imagination. Some yeasts just tend to throw diacetyl: 1084, 1187, 2308 maybe others. It can also be caused by contamination and as you pointed out, poor fermentation dynamics.

That's good to know, any other commonalities in these beers?My impression is that 1084 is a fairly common ale yeast, most people don't do diacetyl rests with ales, and most people don't get problems with diacetyl.

[MtnBrewer]

Most people do diacetyl rests for ales whether they realize it or not. Also, 1084 is not the most egregious diacetyl producer. Of those three, it probably throws the least.

[ThroatwobblerMangrove]

Most people do diacetyl rests for ales whether they realize it or not. Also, 1084 is not the most egregious diacetyl producer. Of those three, it probably throws the least.

yeah - unless you are fermenting really cold for an ale that was my understanding as well.

[MolBasser]

A properly fermented beer (ale or lager) made with fresh yeast should not require a diacetyl rest. My suggestion is to taste a beer, and see if it tastes like cheap buttered popcorn. If so, you may need to re-visit your yeast handling in future batches, and you can save your current batch with a D-rest.Diacetyl rests are done by pro brewers in order to use lower quality yeast. Diacetyl is typically produced by metabolic mutants after many generations of yeast propagation, and fresh yeast from Wyeast or White Labs or any reputable supplier won't throw diacetyl for the first couple of beers you make with it.

With all do respects, and I mean this to be most calm.You are wrong. Very, very wrong.Diacetyl rests are needed for both styles. You CANNOT avoid it. It is part of yeast biology, not poor yeast handling.Ales pretty much take care of themselves, but I dare you to taste your bottles (those that bottle condition) as they carbonate and you will see the Diacetyl jump big time in the first couple days.It just is how yeast work. I have no idea where you got your misinformation.And, once again, please take no offense. It is just that hundreds of years of brewing science shows that your opinion is not supported by the data.MolBasser

[MolBasser]

I hope that I didn't piss people off with that post, but it is just a fact of fermentation.The literature is extensive on this subject.MolBasser

[ThroatwobblerMangrove]

I hope that I didn't piss people off with that post, but it is just a fact of fermentation.The literature is extensive on this subject.MolBasser

I'm cool.

[davelew]

No offense taken.However, I'm still confused about why your theory doesn't agree with my experiments. I pitch large amounts of lager yeast into all-barley worts, let it ferment out, ramp down to lagering temperatures over a week or two, rack to secondary, and don't taste any diacetyl (I've also tried crash cooling instead of slowly ramping, and I feel like the beers are less crisp although neither method results in diacetyl).If diacetyl rests are required, then why don't I taste diacetyl in my beers without diacetyl rests?

With all do respects, and I mean this to be most calm.You are wrong. Very, very wrong.Diacetyl rests are needed for both styles. You CANNOT avoid it. It is part of yeast biology, not poor yeast handling.Ales pretty much take care of themselves, but I dare you to taste your bottles (those that bottle condition) as they carbonate and you will see the Diacetyl jump big time in the first couple days.It just is how yeast work. I have no idea where you got your misinformation.And, once again, please take no offense. It is just that hundreds of years of brewing science shows that your opinion is not supported by the data.MolBasser