Thoughts on esters

[zwiller]

Curious what the brew science guys think is the best way to develop and keep the fruity esters of belgians, saisons, etc. I think there is consensus that pitching at low temperature will keep the higher alcohols and fusels out of the equation and raising temps near peak fermentation produces more esters, but I don't see much posted about post fermentation or aging. Typically I do single stage ferments and ferment at elevated temps for 5-7 days and then drop to cool room temps (65F) for a week or 2 on average strength stuff and just keg... I have seen some say that beers with such yeast expression should be aged a long time/months. Recently, there was a post that suggested to get the beer off the yeast ASAP after fermentation to preserve such esters. Anyone have thoughts? Thanks in advance.

 

[Calichusetts]

I'm not really an expert on the science, but for me and my saisons, this works best:

No oxygen prepitch (or at least no oxygen systems, just a shake.) I read somewhere that as your yeasts multiply while feeding on oxygen, they are also consuming the precursors that produce esters during fermentation.

Under-pitch. Stress them out and force them to produce the population needed for fermentation.

Temperature is a tough one, higher temps mean more esters but possibly some fusels. I tend to pitch about mid-range of the recommended yeast strain and ramp it up every day.

 

[trentm]

Curious what the brew science guys think is the best way to develop and keep the fruity esters of belgians, saisons, etc. I think there is consensus that pitching at low temperature will keep the higher alcohols and fusels out of the equation and raising temps near peak fermentation produces more esters, but I don't see much posted about post fermentation or aging. Typically I do single stage ferments and ferment at elevated temps for 5-7 days and then drop to cool room temps (65F) for a week or 2 on average strength stuff and just keg... I have seen some say that beers with such yeast expression should be aged a long time/months. Recently, there was a post that suggested to get the beer off the yeast ASAP after fermentation to preserve such esters. Anyone have thoughts? Thanks in advance.

Here are my thoughts. Many Belgian yeast strains have been selected to produce esters and will regardless of fermentation temps. The trick is getting the ester flavor/aroma profile for your taste/style. At higher temps, my experience is banana/bubble gum. Lower temps, citrus/apple/pear. Fortunately, higher alcohols at lower temps can produce the sweet character I shoot for while striving for low final gravitates. At higher temps, hot/solvent.

While it is true that lower pitching rates will increase ester production, without knowing for sure the vitality, viability and cell count of your culture, the risk is big. IMO adequate oxygen is also important the help ensure complete attenuation (a quality found in most Belgian styles).

Here's what I do to get to flavor/aroma profile I like in my bigger Belgian Pales and Saisons: Pitch 750,000 cells/ml/degree Plato into 62 degree oxygenated wort and maintain 62 degree ambient temperature. This gives ~15 hour lag. As the log phase begins the temp will rise on its own to ~67 degrees. However as the fermentation goes over the peak the temp will start to fall. So that's the time I start boosting the ambient temp by 2 degrees per day until it reaches 72 degrees. I have found that shortly after high krausening the temp of the beer tend will match ambient.

 

[zwiller]

Thanks guys. So both of you advocate ramping temps. I just start applying heat after I hit high krausen. Might be something to fool with.

What's your protocol after primary fermentation? You guys age a long time and at what temps? I am trying to age a bit but truthfully I would much rather just crash cool after a week of elevated temps... There was a recent thread where one brewer thought keeping the beer on the yeast reduced the impact of the esters and that racking to secondary helped lock them in...

I could have been more specific in that I am looking to improve the ester quality that I am getting. I tend to get "fruity" esters and am fortunate that no fusels show up and it is not bad but the pros get more distinct esters and are much more realistic than what I get.

 

[trentm]

Thanks guys. So both of you advocate ramping temps. I just start applying heat after I hit high krausen. Might be something to fool with.

What's your protocol after primary fermentation? You guys age a long time and at what temps? I am trying to age a bit but truthfully I would much rather just crash cool after a week of elevated temps... There was a recent thread where one brewer thought keeping the beer on the yeast reduced the impact of the esters and that racking to secondary helped lock them in...

I could have been more specific in that I am looking to improve the ester quality that I am getting. I tend to get "fruity" esters and am fortunate that no fusels show up and it is not bad but the pros get more distinct esters and are much more realistic than what I get.

I do not understand the science of ester production or quality so I don't really know what is happening from a scientific standpoint after fermentation but I believe that time is the most important variable with temperature also playing a critical role. But it is the yeast that do the work and I believe it is the yeast that remain in suspension that are most important. So IMO after fermentation is complete (no measurable drop in gravity for 3 days) there is still a lot happening concerning yeast metabolism and it happens very slowly (several months). So for me the trick is to stay out of the beer until it is really ready. This is a challenge because the beer can be quite drinkable after 2-3 weeks in the primary < 1 week cold crash then carbonated. I did this for years with great results but I could not stay out of the beer for the 3 or so months conditioning that takes the beer from quite drinkable to FANTASTIC!

Here is the process I now use: First let me say, I use yeast that have been isolated from some of my favorite Belgians and I have selected from those isolates less flocculating individuals. So while most of my isolates are available commercially, they are less focculant than their commercial relatives. Now here is my process: After complete fermentation, I move the beer to a bright tank (I don't use the term secondary because it's a dirty word on this forum) and maintain the temperature at 72 F for a week or so. Then I began dropping the temp by 2 degrees/day until it reaches 40. This slow drop allows the yeast to stay in suspension and to continue metabolism (yes, even ale yeast will metabolize at 40 F). The beer remains at 40 for at least 6 weeks but can stay as long as you like (I've gone as long as 5 months). After this period, even my low flocculating yeast have mostly drop out but I drop the temp to 32 and give it another week or more. More than anything else this whole process keeps me out of the beer during the conditioning phase. After the rest at 32, I bring the temp up to 70 over a day or so, re-yeast and bottle. After bottle conditioning for 30 days or so, it's fully ready to drink. I am not sure this extended conditioning is any better than extended conditioning in the bottle but for me it at least keeps me out of the beer until it is really ready to drink and there may be some thing about keeping the yeast active and cold.

 

[zwiller]

Thank you for taking the time to post that info. Extended aging is tough for me. I admit it, I am not a patient man, especially in terms of homebrew. That said, this basically confirms my worst fear that I need to be aging belgians longer (much longer). Can't say I can do the extended bulk conditioning, but I have been thinking about grabbing 2 cases of champagne bottles to fool with. I might be able to get more age on them that way.

So if I understand your theory, the goal is is to keep the yeast in suspension so they can continue to metabolize and remove some of the less desirable compounds. Makes sense.

Since you are obviously are more experienced with belgians that I, can you recommend a commercial strain? Although not trappist, I really dig anything from St. Bernardus. Never had some of the rare, travel to Belgium stuff though... Have used 3787 in the past and found it bland. I am partial to tripels. Thinking of a tripel with 3522.

 

[trentm]

Thank you for taking the time to post that info. Extended aging is tough for me. I admit it, I am not a patient man, especially in terms of homebrew. That said, this basically confirms my worst fear that I need to be aging belgians longer (much longer). Can't say I can do the extended bulk conditioning, but I have been thinking about grabbing 2 cases of champagne bottles to fool with. I might be able to get more age on them that way.

So if I understand your theory, the goal is is to keep the yeast in suspension so they can continue to metabolize and remove some of the less desirable compounds. Makes sense.

Since you are obviously are more experienced with belgians that I, can you recommend a commercial strain? Although not trappist, I really dig anything from St. Bernardus. Never had some of the rare, travel to Belgium stuff though... Have used 3787 in the past and found it bland. I am partial to tripels. Thinking of a tripel with 3522.

My pleasure, I really enjoy talking yeast. Extended ageing is a challenge for me as well but it is the best thing you can do for the bigger Belgians. I have had mediocre beer evolve into great beers in a few months time. The problem for me can be that they are mostly gone by that time. Getting ahead on my brewing and bulk conditioning have solve most of that problem for me.

I regret that I don't have much knowledge on commercially available Belgian yeast. I have been using my own strains for the last 5 years, so I haven't kept up. One of my favorites, is my isolate from Orval but that's a trappist, however quite different from the others, I love the spiciness. It's commercial relative is WL 510 Bastogne. For my tripples and golden strongs I use an isolate from Delirium Tremens. I don't know if it is commercially available. For my Blondes I use an isolate from Moinette Blonde. It's brewed by DuPont but a different yeast from their Saison. It produces fruity esters with bit of a floral nose (if you haven't tried Moinette Blonde it is worthwhile to find one if you can). I often do a mixed fermentation with it and the Orval strain for Saisons. Again I do not know if the Moinette strain is available commercially.

It seems there are a number of well informed yeast enthusiast on this forum. Perhaps it would be worthwhile to post the question to them.

 

[zwiller]

Thanks. It might sound like a sacrifice but I have really been dialing in things towards a shorter brew day and this is allowing me to brew more often. (Young family, etc) Brewing more often keeps me out of the beer, as you put it. Will try my best to put some aging on these beers. I tell myself, at least it's only a few months and not years like wild beers or wine.

You reminded me, apparently many folks have been quite successful with dregs of DT. Long overdue to try that. Never had Moinette, will check it out. I think Duponts flagship beer is overrated. I need to source some Blaugies. Years ago on another forum someone suggested me to try 3726 for a saison which is apparently Blaugies strain and every beer I make with that yeast is fabulous. Normally I just keep some dregs of yeast I like in the fridge and looking to get a bit better at it and recently got some 50ml centrifuge tubes to try freezing yeast with glycerine. Can't say I will ever get to isolating strains... Thanks again.