Mein bisschen Deutsch isn’t up to the task, so I was wondering if someone on here could take a look at this for me: http://d-nb.info/978186087/34
According to Kai the paper shows that increased pitching rates leads to increased ester production, so I wanted to know more about what the author is talking about.
I can tell you that has been verified a number of times. Neva Parker mentioned it in her AHA seminar last June. It came up in a question I asked to Dr. Clayton of Lallemand many years ago in HBD’s “Fortnight of Yeast”. (http://www.danstaryeast.com/articles/yeast-growth). The basic mechanism is that the same enzyme, acetyl co-A, is responsible for both yeast growth and ester production. If it’s doing one, it can’t do the other. So, if you pitch the right amount of yeast, you get cell growth but reduced ester production. If you pitch too much yeast, the enzyme produces esters because it doesn’t need to work on cell growth.
That’s the best, and most straight-forward, explanation I’ve read to date regarding yeast growth and ester production. Thanks Denny.
It sounds like underpitching-for-more-esters is one of those “zombie” ideas. No matter how many times people kill it, it just keeps coming back.
If you believe any number of brewing scientists, you are absolutely correct.
Interesting. So this suggests under-pitching versus over-pitching for lagers is better?? Or just plain pitching the proper amount and that’s that.
At the NHC, Neva Parker stated that the following are true. She said that there are also some recent papers from Japan that state this.
Underpitch - More fusels, less esters.
Overpitch - Less fusels, more esters.
This was challenged from the audience, as we have all read the opposite from our books. She said that it is the correct facts.
That squares with my completely unscientific, anecdotal experience. It also explains why there are so many homebrewed fusel-bomb Belgian beers.
How long does it usually take for the presentations to get uploaded on the AHAconference.org site? I’m really interested in that Neva Parker presentation.
If you can’t wait, my understanding is that Neva Parker’s presentation on Northern Brewer/Brewing TV is fairly similar to the NHC presentation:
There are more variables at play than just pitching rate; yeast health, pitch temperature, fermentation temperature, wort gravity, and oxygenation rate. So, to just say that pitching rate affects everything is just the tip of the iceberg (Neva covers some of this in here video presentation, namely oxygenation).
Yeah, I try to hold a nuanced, balanced opinion. I want yeast to make flavors I like, and I don’t want yeast to make flavors I don’t like, and I’m open to any information that helps me accomplish that.
I sent out beer to some of the guys on this forum, and the feedback I’ve received has been really enlightening. I’ve decided I have no ability to objectively evaluate small changes in my technique. I think I’m cool and smart, with a good palate, but it turns out I’m not capable at all to discern subtle differences in the beer I make. Other homebrewers also think they’re cool and smart with a good palate, so I’m really starting to doubt the veracity of some of their claims regarding subtle differences.
I think it’s because lowering the pitching rate increases phenol production, and people get the two confused.
Kate had hoped to have them up this week. Since that didn’t happen, I’d guess they’ll be there soon.
Too few people take this objective viewpoint. That’s why I started doing blind group tasting years ago and why I so frequently question people who say that certain things make a definite difference in their beers.
I haven’t heard that before. Do you have a link to your source for that? I’ve been poking around on Google looking for more info, and came across this: http://www.scientificsocieties.org/jib/papers/1996/1996_102_5_327.pdf which I found interesting, but they didn’t mention pitching rate’s influence.
Surprisingly, a large amount of 4-VG is formed during the boil, and Weizen yeasts have only a weak ability to decarboxylate ferulic and cinnamic acid. It does appear that a ferulic acid rest at 45*C really does make a difference, though, so I’m surprised by that.
“the formation of 4-VG continued at steady rates throughout the boil” < This might be why in Eric Warner’s German Wheat book he recommends a 2-hour boil.
Neva was going over homebrew myths about yeast, and was directly addressing the one about a lower pitch rate causing more esters. Of course there is more to it than just pitch rates as you listed, and one could include yeast strain to that list.
Like decocting lagers, right? I think that was one of your taste tests…Didn’t some in the group actually prefer single infused over decocted lagers?
I’m still waiting on a couple results, so I won’t comment until all the feedback is in, but I’m sure there will be a lively discussion once I’ve sorted through the responses and put the results up on the forums.
Edit: Were you talking about Denny’s decoction study? It was mostly single-decoction vs regular mashing, IIRC, though he left that up to the individual brewers to decide. It was also a range of beers, if I remember correctly. The “preferred infused” and “no preference” taken together were the majority opinion, though there were a slight preference for the decocted beers over the infused beers. The conclusion Denny drew was that decoction doesn’t produce a beer that’s clearly preferred, which I think is fair.
I’m not sure about the breakdown of individual choices, and how many people sampled which beers. Just from the chart I saw, it’s possible about half the people preferred the decocted beers every time, and the other half preferred the infused every time. If people preferred, say, one infused, and a different decocted, with no significant trend in preference, then that would be clear support for Denny’s conclusion.
Yep. and if you add together those who preferred the non decocted beers and those who had no preference, it was more than preferred the decocted beers.