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Messages - a10t2

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This is a question that I see all the time on homebrew forums and nobody seems to have a definitive answer for yeast count per unit volume of settled yeast. Or at least the ones that claim to don't agree.  We have yeast count but then we also have viability and non-yeast percentage numbers and everybody seems to be guessing at all three.  It seems the yeast count of settled yeast part should be straightforward enough.  Guessing at two variables is better than guessing at three.

There was a pretty good back-and-forth on the NB forum a couple years ago.

By a couple different methods, I concluded that a fully packed slurry will be about 4.3 billion cells per mL. Jamil Zainasheff, who's probably as much an authority in this as anyone, says 4.5 billion/mL. So I think you could take that to be fairly accurate. Similarly, if you're rinsing the yeast with sterile water, it seems to me - at least visually - that the non-yeast portion drops pretty darn low even after a single cycle. So figure 0-10% on that, make your guess at viability (25% loss per month, refrigerated and stored under beer/water is a pretty well-established figure) and you'll probably get your overall cell counts within ±20% or so. That actually compares pretty favorably with typical use of a plate hemocytometer, and is good enough for our purposes IMHO. It's only beer.

He claims that it's impossible to have an ATC refractometer measure both.
I totally disagree.

Your friend is right, although he probably doesn't know why. A refractometer can only *measure* the refractive index. ;)

Questions about the forum? / Re: CSS, no list styles?
« on: April 28, 2011, 09:13:28 AM »
There shouldn't be any CSS involved anyway. Or rather, there could be since you can div anything, but li and ul are both implemented in straight HTML:

You're right, though, it does look like those tags have been CSS-ed out. Someone should either enable them or remove the icon from the WYSIWYG menu.

Equipment and Software / Re: Refractometer.....
« on: April 27, 2011, 06:03:41 PM »
I bought mine off ebay as well.  The SG scale is generally 3-5 points over my hydrometer and worse as the gravities get higher.  I've used it for the last 10 batches or so and the variance has been there every time.

Are you applying a wort correction factor? Typically you'd subtract 4% from the raw Brix reading to account for the different refractive indices of the wort sugars.

Zymurgy / Re: May/June Issue, already?!
« on: April 27, 2011, 03:11:48 PM »
Sweet. I've been checking the mail almost every day waiting for this one. ::)

Equipment and Software / Re: SG/Brix refractometer completely useless?
« on: April 27, 2011, 03:09:51 PM »
I think I'm the one who started this...

With the caveat that I've never actually used one of these and and am working entirely from the pictures I've seen online, yes, the SG scale is inaccurate. The manufacturer appears to have used the "multiply by four" rule, rather than an actual Brix-to-SG conversion. So the Brix scale should be just as accurate as any other refractometer, but the SG scale will only be within one "point" up to about 1.050. As far as I know, the Brix scale is still a pure sucrose measurement, so you'll need to apply a correction factor when measuring wort.

This post has some general information on how to use a refractometer, as does the September 2, 2010 episode of Basic Brewing Radio:

For FG estimation, I have a recently updated spreadsheet, which glastctbrew linked to earlier:

This *should* give better results than the MoreBeer/ProMash/BeerSmith/what have you formula, although that's also included so that people can verify it for themselves.

All Grain Brewing / Re: Mashing for high gravity
« on: April 27, 2011, 09:00:45 AM »
You might want to use DME instead of LME and the lightest you can get as well. when doing a high gravity the LME can add a lot of unfermentables that can result in an overly sweet beer IMO.

I think that in general LME would be more fermentable, actually. I don't have any personal experience, but that was Ray Daniels' conclusion in Designing Great Beers. He found only one manufacturer's (M&F) syrup was less fermentable than their DME.

All Grain Brewing / Re: Maintaining water temperature...
« on: April 26, 2011, 03:05:54 PM »
I was wondering if my soupy mash contributed to the rapid heat loss.

I think it's more likely that you actually just didn't have a uniform temperature at the beginning and so it was lower overall than the spot you checked. I have that same cooler and I've never seen a mash drop more than ~2°F in an hour.

All Grain Brewing / Re: Forgot mash-out
« on: April 26, 2011, 11:50:53 AM »
That's what I have understood to this point. That's why batch sparging results in small loss of efficiency isn't it?

Right. The more you divide up the sparge into smaller and smaller batches, the more thoroughly it's possible to rinse the grain bed. When fly sparging, the number of "batches" is infinite, so efficiency is maximized.

Well, I think a mash out and sparging with water to keep it just below 170F helps a lot, at least it has in my experience.

That's what I was wondering about - once the mash has fully converted, I'm not sure what the mechanism would be that would improve lauter efficiency based on temperature. Kai even did a batch sparge using cold (15°C) water and the efficiency compared to the hot sparge was about the same. It sounds like your results were different, though. Were the batches otherwise identical?

All Grain Brewing / Re: Forgot mash-out
« on: April 26, 2011, 09:59:56 AM »
Given plenty of time for complete conversion, a mash out would only improve lauter efficiency.

Assuming 100% conversion before beginning lautering, wouldn't the lauter efficiency depend only on how much water is run off, and in what increments?

Beer Recipes / Re: Oktoberfest 2011
« on: April 26, 2011, 09:24:24 AM »
The Wyeast version of the same thing (I don't recall the number offhand) is just fine.  It's just the 820 that's bad.

That would be 2206, FWIW.

All Grain Brewing / Re: Mashing for high gravity
« on: April 25, 2011, 09:46:38 PM »
In order to keep efficiency constant, you have to keep the ratio of mash and sparge liquor to grist weight constant. That means boiling longer to end up with the same final volume. As a practical matter, it's better just to use more grain (or extract, if you prefer) and take the efficiency hit associated with keeping the boil time constant.

All Grain Brewing / Re: Forgot mash-out
« on: April 25, 2011, 08:13:16 PM »
The whole idea behind a mash-out is to fix the fermentability of the wort before starting the sparge. If you're trying to maximize attenuation, some extra time at mash temperature could only help.

All Grain Brewing / Re: Forgot mash-out
« on: April 25, 2011, 06:38:06 PM »
Are you batch sparging or fly sparging?

Regardless, when mashing for high fermentability like that, I don't think you'd want to mash out.

General Homebrew Discussion / Re: Fastest Turnaround Time?
« on: April 25, 2011, 11:41:59 AM »
I just tapped a blonde ale ten days after brewing. I don't really like to carbonate at high pressure, though, so it was actually in the keg on day 6.

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