Drauflassen: Has anyone experimented with frequency of adding wort?

[Silicon]

I've been reading about drauflassen* and am curious if anyone's tried this; and, if so, have you tried varying the frequency of adding more wort to the fermenter?

Essentially, I'm pondering the difference of adding large amounts of wort daily vs. smaller amounts hourly (or even continuously). I'm wondering how yeast would behave if in a fairly continual growth phase (hourly) instead of daily cycling back-n-forth between aerobic and anaerobic. Or even the extreme: adding wort at a slow, constant rate until all wort has been added.

Thoughts?

* Examples:
http://braukaiser.com/wiki/index.php?title=Drauflassen
https://beerandbrewing.com/dictionary/KU8vZ0OyWJ/
https://prostbrewing.wordpress.com/2014/07/04/drauflassen-is-part-of-our-method-to-bier-perfection/

[brewfun]

Most commonly, this is the technique to add multiple batches to the same fermenter. A point which your articles make pretty quickly. In pro brewing, it's applied equally to both ales and lagers and doesn't lead to "better beer" by itself, just more of the same quality that the brewery is capable of more efficiently. The technique changes slightly when triple or quad batching when aeration is reduced or eliminated from the third batch onward.

The major advantages are that the brewery can pitch lower amounts of yeast, which means they can be even more selective about the slurry viability and quality. Effectively replacing a lab growth step by putting yeast into the fermenter instead. The next advantage is to the process where the yeast management procedures are geared towards single batch inoculation.

For a homebrewer, it can replace part of the pitch up process, saving space and time. For any given volume and viability of yeast, there's an ideal gravity and volume of yeast. Adjusting that first wort portion for the yeast will improve the overall fermentation. If you already have the right amount of yeast for the total batch, then delaying finished wort seems to be a risky waste of time.

Note that in the pro brew version, wort is NOT set aside to be added later. It goes right from chilling to the fermenter.

Garrett Oliver has said he uses a similar technique to refresh tired yeast that's been harvested from high gravity beer. He adds it to a low gravity wort at slightly high pitching rates to refresh it. Myself and others do the same to get more generations out of it.

Continuous fermentation is a whole separate thing. It's not used by very many brewers because it's hard to manage the yeast and sanitation issues that arise. Plus, it's like a non-stop train that can't respond to seasonal variations in demand.

[Silicon]

Cool, questions answered and you've given me more to think about...much appreciated, thx!  I think I'll do some experiments with smaller amounts and see how they fare over time. Meanwhile, I'll stick to my tried-n-true method, only using calculated pitch rates, something I've just been learning from you guys.

I'm curious as to how yeast will do if kept in an aerobic state for an extended period. I've read of yeast getting tired, undergoing mutations, etc...those kinds of things.

1 thing I'm curious about, though: do you think adding wort over an extended period (e.g. a week) would result in the yeast altering the final flavor?

(As for wort sanitation, I don't plan on storing wort but actually boiling it in multiple smaller batches so what I'm adding to the fermenter is always fresh.)

Still thinking...

[brewfun]

I'm curious as to how yeast will do if kept in an aerobic state for an extended period. I've read of yeast getting tired, undergoing mutations, etc...those kinds of things.

It depends on how you're "keeping" it. On its own, yeast will keep plugging along, but it only cares about eating sugar, not making good beer. If you mean fermentation, it does need to go through it's full cycle to dormancy from time to time, so that it can rebuild sterols and maintain healthy cell walls down the generations. This means the proper nutrients and trace minerals.

Many yeasts don't like being in environments over 6% abv. In low nutrient wort (often extract batches) the yeast don't build cell walls that will allow consumption of complex sugars and in worst cases only process the glucose. This leads to stalled fermentations. Another issue can be flavor changes due to low pitching rates and/or incorrect temperatures.

Again, unless you're developing a house yeast that you intend to use for every beer and will keep it active, it's probably not a big deal. Proper pitching rates, oxygenation and temperature control are the best methods for ensuring a good beer. If you happen to be using extract, a bit of yeast nutrient will help it dry out completely.

1 thing I'm curious about, though: do you think adding wort over an extended period (e.g. a week) would result in the yeast altering the final flavor?

It depends. How much wort to how much yeast? I think there can always be a flavor change because different strains of yeast react differently to the same conditions. If all yeast acted the same, there wouldn't be the strains available.

The real question is if you have to split 5 or 10 gallons into smaller increments, is it really worth your time or should you invest in equipment? It might be a fun experiment for a week, but is it something you need to do every batch? Again, a comparison of homebrew to pro brew techniques doesn't necessarily lead to sensible conclusions.

[Silicon]

Yes, I definitely need to get the Yeast book. I'd been reading (online) that yeast is only good for so long and then mutations accumulate and new yeast is needed. So maybe I'm missing something from what you're saying--or over generalizing maybe--but just how long can I keep yeast going, batch after batch? I'd like to get the most out of each yeast pack that I can, of course, but I don't want to overdo it.

Also, I think the book will teach me more about yeast's lifecycle which will in turn change all these ideas I keep having (e.g. long-term steady wort feed giving 1 extended stage vs. multiple stages).

Eventually, I'll have the funds to switch-up from carboys to a 20gal fermenter which, I think, will be my "sweet spot". I plan on buying equipment to get my own accurate cell counts, too. But maybe I need to swap priorities for now.

Hey, thx again for sharing. All you guys are helping more than the hours I'm spending reading general stuff online, much of which varies wildly from site to site, just like I"m finding with the online yeast calculators. It's hard to pick a proper pitching rate when every site says something different and, as people in 1 of my other posts are saying about White Labs' data, people's actual results are differing greatly from WL's data.

[brewfun]

I'd been reading (online) that yeast is only good for so long and then mutations accumulate and new yeast is needed.

Yeast does evolve to get comfortable in a brewery. For me, the first generation pitch right from the manufacturer shows off all of the lesser traits (sulfurs, longer lag time, longer to flocculate, etc) but by the third generation, it's smoothed out and the results become a lot more consistent. There's nothing wrong with the first couple of generations, it just takes a few days longer for the beer to mature.

I have no way to know if actual genetic mutations are occurring (though statistically, they certainly are) just that some traits express differently according to the conditions I give it. I tend to run slightly cooler fermentation for ales and usually under pressure for the first 72 hours. After that, the pressure is slowly released, which scrubs sulfurs faster than atmospheric fermentation. Each batch gets nutrient and a bit of extra zinc.

I suspect what some homebrewers are experiencing are changes due to high temperatures, high trub loads, high alcohol and bacterial accumulation more than the actual yeast just transforming itself.

So maybe I'm missing something from what you're saying--or over generalizing maybe--but just how long can I keep yeast going, batch after batch? I'd like to get the most out of each yeast pack that I can, of course, but I don't want to overdo it.

I can't speak for every brewery, but I repitch out to 12 or 14 generations in the range of 4 to 7% abv and don't repitch from anything 8%+. Occasionally I get to 20 (which is about a year), but I start worrying about the inevitable bacterial load that accumulates.

Generations are different than batches in pro brewing. I can get two repitches from a fermenter, so there is exponential growth possible in batches. I've had as many as eight fermenters going on the same generation, but usually it's two or three. The main reason is economic because buying a pitchable volume can be as much as $500. My overall yeast cost is about $1.25/bbl.

EDIT: Oginme lays out a very practical and reliable set of repitching guidelines, here: http://www.beersmith.com/forum/index.php/topic,20543.msg73192.html#msg73192

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Wow, so much to learn about yeast...every answer is generating more questions and ideas. I really like what you said about brewing colder as I do that with my ales (low end of any given temperature range) even though a guy at work thinks I'm nuts. It just makes more sense to me and I don't mind the longer fermentation periods (and I suspect my new learning of proper pitching, resulting in more yeast/patch will shorten that back to normal).

I was saving Oginme's post (which you linked to as well) for after dinner and workout so I can finish my plan for starting tomorrow. I'm kinda torn between his methods 2 and 3, but I'm leaning a bit towards 3. It'd help if I had more equipment (that'll have to wait for a while, still), but his 4.5b cells per ml would make a good "general rule" for me. I've read about cleaning trub with water to get a better concentration of yeast, but I like his idea of going half-n-half, a remaining beer plus water; it seems like a great compromise and he's getting pretty clean yeast, which is pretty important to me AND the diluted beer is a nice bonus.

BTW I'm ordering the Yeast book tomorrow...got a bonus in my latest paycheck so am putting it to good use. OMG, even my wife thinks it's a good idea and she's not the greatest beer fan on the planet, either.

Thx again, sure hope I can return the favors for you guys some day. I'm learning a lot and I owe a lot of it to you guys, y'know.