i watched a podcast with charlie bamforth and he mentioned active yeast loves to “mop up stale stuff” which i assume he means oxidized characters, so i have a sour beer that is just going on 1 year old and its a bit card boardy, do you think making a starter and pitching at high krausen would actually help? i was thinking it would reduce the head space as well, anybody have any experience with krausening beer?
Kräusen beer is one of many things that can scavenge oxygen and thereby reduce the risk of future oxidation. Once oxidation has occurred it cannot be reversed. Best practice is to avoid opportunity for exposure to oxygen in the first place.
Once the beer has entered the realm of this level of oxidation, there is no turning back for it. Adding active yeast via krausening at this stage will do nothing to improve the stale papery, cardboard notes caused by trans-2-nonenal.
gotcha, eh oh i guess i will brew another one and pay attention to the airlock this time
since im on the topic of sours, what is a good yeast to use at bottling? would cb1 be ok with the acidic environment? or would a wine/champagne yeast be more preferable
If your sour has Brett, than no need to add yeast unless you want to carb quickly. Champagne yeast works well. I have no opinion on CB1.
Interesting this came up today, I am going to use krausening (aka shaken not stirred starter) to start my Exportbier. I am hoping to hit high krausen tomorrow AM about the same time my wort reached 55*F.
Here’s an article from AHA that also mentions krausening cleaning up oxidation:
That’s not really Krausening.
Krausening would be carbonating your beer with actively fermenting wort.
What you are describing is a vitality starter.
True …but I apply a loose interpretation: “While all instances of krausening are technically activating fermentation, the process can be used for various instances of either starting or restarting fermentation. Using the krausening technique to initiate fermentation is essentially the same as making a starter, where the entire contents of the starter would be added to the wort at the height of its activity.”
i know german brewers add fresh wort at high krausen to carbonate but im pretty sure the true purpose of krausening is to remove VDK’s(diacetyl and pentandione) to clean the beer up
“While carbonation was the primary goal of krausening in traditional German lager brewing, it was also recognized as a way to clean up some of the “green” qualities found in young beer by aiding the maturation process. It can also be used to help with flaws such as diacetyl and acetylaldehyde. Adding more yeast through krausening is also said to help reduce oxidation in batches that may have been unintentionally aerated.”
Both. It’s a way of adding fermentables to carbonate, that has the added benefit of providing fresh young yeast ready to go to town cleaning up what the old tired yeast might not. But of course it evolved without anybody thinking it through that hard. In the old days they were just topping up, with fresh beer they had on hand, casks that weren’t full because beer had foamed out of the bung hole during active fermentation. (Can’t sell the tavern a cask that’s not full. Some brewers just used water. Others primed with sugar solution or plain wort, called Speise in German.) Result: “Hey, check it out, Hans, this beer is now fizzy and clean tasting! I’m gonna keep doing that. Tavernkeeper says he’ll pay us more than the guy who just tops up with water.” Much later, science and silly German beer laws.
I was just reading through Chapter 6 of Freshness by Bamforth, and I noticed the following passage:
“I think the answer lies with yeast. Yeast loves to reduce carbonyl substances. If you take a beer with pronounced cardboard/wet paper character and treat it with a good virile yeast, the stale notes will be removed.”
I assume he’s talking about beer in process or he means krausening and doesn’t specifically say it. Otherwise, if you did it post fermentation, what would the yeast have to work on?
I wonder if even kräusening would be practical in this case. How much yeast activity would be needed, so how much unfermented beer would need to be mixed in? This could wreck the character of post fermentation, fully matured, or packaged beer, a case of “the operation was a success but we lost the patient.”
Exactly
I really don’t know (beer in process wouldn’t yet be at the point where it has a cardboard/wet paper character would it?).
I’m going to read the rest of the book this week. It’s short but pretty dense. And I believe he covers E-2-nonenal in greater detail in an earlier chapter. I’ll post back if I see anything on point.
One other tidbit I noticed in Chapter 3:
“If you take a stale beer and add enough sodium metabisulfite to it, then you can clean up the flavor. This speaks to the fact that sodium metabisulfite binds carbonyl substances to produce so-called adducts, which no longer display the aged character.”
The carbonyl group includes diacetyl, acetaldehyde, and E-2-nonenal.
I’m not saying the OP should do this or that to his beer; I just wanted to share a few things I came across that I think are interesting.
Yeah, that’s what I was getting at. If it’s still fermenting, how do you know it’s oxidized? And if it’s done fermenting, what’s the yeast gonna work on? I thought in a long ago discussion we found that adding sulfite to a finished beer was not a good idea.
That is interesting
Kunze says it is done to prevent or forestall oxidation in packaged beer. But again as with kräusen, as a practical matter after the fact, I’d think the amount needed to reverse the problem would be its own fatal problem.