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Messages - dimik

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General Homebrew Discussion / Re: IPA's and Caramel Malts
« on: November 07, 2012, 12:17:22 PM »
Probably depends on your own tastes and what you like.

General Homebrew Discussion / Re: Homebrewing Hobby Survey
« on: November 07, 2012, 03:50:02 AM »
I think of scientists are people that use the scientific method to answer questions (hypothesis->experiment->observations->conclusions), so Kai and Sean would qualify.
Hehehehe, that's what laymen think about the inner workings of research. It's very different on the inside :)
Then you're doing it wrong. ;)
(I'm not a layman, by the way, I'm a biochemist.)

Biochemist and enzymologist turned developmental biologist here :) You've got to tell me your secret!
This is closer to my research experience (

General Homebrew Discussion / Re: IPA's and Caramel Malts
« on: November 07, 2012, 02:47:17 AM »
The best IIPA I never made had 10# 2-row, 3# munich, 1# C60 and 1# sugar. Ton of Cascade, Centennial and Summit. Not pale at all, but just a perfect balance of delicious malt and a blast of hops playing together like a symphony. 166 IUB btw...

Yeast and Fermentation / Re: 100% Brettanomyces (or similar) fermentation
« on: November 07, 2012, 01:04:14 AM »
Yup. Brett likes to take time to start up. It's due to their nature - they are naturally slow growers and fermentors.

General Homebrew Discussion / Re: Homebrewing Hobby Survey
« on: November 05, 2012, 01:59:10 PM »
I think of scientists are people that use the scientific method to answer questions (hypothesis->experiment->observations->conclusions), so Kai and Sean would qualify.

Hehehehe, that's what laymen think about the inner workings of research. It's very different on the inside :)

Yeast and Fermentation / Re: Long-term sour starter
« on: November 01, 2012, 03:28:17 AM »
I think what will end up happening this way is that whatever you throw in first will be the main contributor to your culture. By the time you throw in your next dregs, the initial organisms will outnumber it probably around a million-billion to one in terms of cell counts and as the nutrients become depleted the new incoming dregs will grow out less and less. They'll be there, but their contributions will not be as big as that of the first and second dregs. Since you desire a house culture that is a mix of these dregs, I think it stands to reason that you'd wish them all to contribute roughly equally, yes? If that is the case what I'd do is split that wort into 1/2-1 gal portions and pitch dregs into each individually. That way you'll have a number of equally happily growing populations that you can later crash, decant, and mix the slurries as you desire in order to pitch into your beer of choice to be the first "house sour."
Just my thoughts...

The Pub / Re: Sandy
« on: October 30, 2012, 01:28:28 AM »
Here in New York it's rocking my building (I live on the 6th floor and feel the building move around) and there is a foot of water running through the streets just a few blocks away! The lights are flickering, the window glass is bending...

Yeast and Fermentation / Re: Pellicle?!
« on: October 30, 2012, 12:20:16 AM »
I have isolated 3 wild yeasts. All three formed pellicles in primary cultures and by the third passage only one of them still readily forms a pellicle. With time though, all three form pellicles whenever they feel like it. So... yeah man, it's wild and does what it wants!

The Pub / Re:
« on: October 28, 2012, 11:04:18 PM »
People need to start coming in again. It was really fun.

Yeast and Fermentation / Re: Post a pic of your Pellicle!
« on: October 28, 2012, 08:25:09 PM »
Here is a pic of some wild yeasts I'm trying to culture and purify right now.
I took some jars with sterilized wort with me on my last hiking trip and collected some flowers and berries in upstate NY forest. Hope something interesting comes from it.

Yeast and Fermentation / Re: Over pitching/under pitching experiment
« on: October 27, 2012, 05:31:01 AM »
S. winlocki anyone?

Yeast and Fermentation / Re: Over pitching/under pitching experiment
« on: October 23, 2012, 01:43:36 AM »
His point is still fair though - older cells don't perform as well.

How old is "older?" Would that happen in a single batch of beer, or are you talking about repitching?
This is a more complicated question than it may seem :)

There are two ways that scientists talk about how old a yeast cell is - replicative lifespan, and chronological lifespan.  Neither of these is investigating the health of cells that are fermenting without dividing over time so the results may not be directly applicable.  With that caveat . . .

The replicative lifespan of yeast is roughly 25, meaning it can divide 25 times before it stops.  I am making a broad generalization here because it is strain specific.  This number comes from my old labs' work on strains BY4741 and BY4742, common lab strains that are the opposite mating types but otherwise the same.  I never did lifespans on any brewing strains because it is a huge pain and requires a dissecting microscope - basically, you plate cells, use the dissector to move individual cells to their own spot on the plate, then incubate for 2-4 hours.  Then you go back to the scope and pull the daughter cell away from the mother, put it in a garbage area, and count that as one.  You do this again and again until the mother stops dividing.  You can't let it grow too long or it can become hard to tell the mother from the daughter, or you may count the daughter's daughter as a daughter of the mother.  It is very labor intensive - we had a group of people who did nothing but pick daughters all day long because they went through the entire yeast deletion collection, ~5000 strains that are the same as above but with a single gene deleted, plus controls, etc.

Anyway, older mothers don't perform as well as younger mothers.  Daughters of older mothers don't perform as well as daughters of younger mothers, although they recover after a couple of generations.  I believe in this case "perform" means grow, they were not checking for fermentation performance or anything like that.

The other kind of aging, chronological aging, is quite a bit different.  In this case, a strain is grown to stationary phase and let sit for some period of time and then tested to see if it will grow again.  Again, the entire yeast deletion collection was screened by a guy I know (much easier for one person to do).  The normal strain was 50% viable at ~2 weeks.  This is misleading though, because the media used affected the results.  Another guy I know showed later that the effect was almost entirely due to pH, and more specifically the ability of the strain to withstand acetic acid.

So, will this happen in a single batch of beer?  The scales for a single fermentation are too short to apply to either one of these sets of data.  If you are constantly repitching replicatively older cells I think you will notice in your fermentations.  But isolating replicatively older cells is a real pain, labs have spent years trying to figure out how to enrich a culture for older mothers.  If you are harvesting from a carboy don't worry about it.  From a conical, as long as you are blowing out the first bit to get rid of the trub, don't worry about it.

If you are constantly over pitching and re-pitching from an over pitched batch, you may be increasing the chronological lifespan of the culture.  However, the data there are not good enough to give a definitive answer.  We know there are pH effects, but the final pH of the research media is not in the same range as beer, the finished culture ends up much lower than beer (under 3) while the buffered cultures they used are higher than beer (pH = 6).  And they didn't do anything with serial repitching of these cultures.

I think I typed all of this stuff and didn't answer the question.  Bottom line - if you follow standard practices you should be fine.  Make starters, aerate well, pitch in the suggested range, etc.  If a culture gets old by sitting for a while, refresh it in a starter.  Don't worry about bud scars.

THAT, Sir, was probably the most interesting thing I've ever read on any brewing forum. Very nice!

Yeast and Fermentation / Re: Over pitching/under pitching experiment
« on: October 22, 2012, 04:43:29 AM »
I've had my share of disagreements with Jason (purely healthy scientific discussion) and I respect his results and observations even if I disagree with them sometimes.

Yeast and Fermentation / Re: Rehydrating Dry Yeast
« on: October 22, 2012, 04:39:49 AM »
Actually it seems to have worked very well.
It bubbled like MAD at 54 for about 2 days in just a couple hours after pitching (was too busy to look at the temperature so ended up with an English "lager" Winter Warmer lol). After that I moved it to my room and it bubbled for one more day and stopped. Not going to even look at it for a few more weeks, but it seems to me like it was the strongest dry yeast induced fermentation I've ever experienced.

Yeast and Fermentation / Re: Belgian Golden Strong
« on: October 17, 2012, 02:33:17 AM »
WY PC Canadian/Belgian strain. It's restrained with gentle apricot and lemon character. Very very nice yeast for a light colored belgian.

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