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Messages - a10t2

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All Grain Brewing / Re: New to all grain a few ?'s
« on: Today at 07:56:01 PM »
not sure but I think you'd be better off at that point stirring it up.  I'd expect a dryish grain bed to channel like a mofo.

You might be better off, but from a practical standpoint it could be better to run dry. I worked on a small brewpub system that had the outlet of the mash tun only about a foot off the floor. Consequently, we had to pump from the tun to the kettle. Switching from no-sparge to what we called "Denny-sparging" took the efficiency in that brewhouse from ~70% to ~83%.

Yeast and Fermentation / Re: New starter procedure trial
« on: Today at 07:25:10 PM »
I'll say that I have $9 invested in my stir plate ($6 of that is the bar), and would have no problem with giving it up. I'm looking forward to trying out Mark's technique once I get my current glut of pilot brewing over with.

For those of us who had statistics so long ago that there were no desktop computers, can you explain the symbol and the formula for this "statistical significance" (p less than .05, for example)?  Near as I can tell, it comes out to about half...which leads to Sean's question about what level is significant, whether statistically relevant or just cuz it means something that can be considered reasonably dependable to base conclusions upon.

I'll try…

The thing that makes a triangle test so statistically useful is that it's binary; each participant either picks correctly, or doesn't. It's a coin toss, and if you toss a coin enough times you can collect valid statistics about how likely you are to get various combinations of heads/tails. The probability that a given heads/tails combination will come up for a fair coin is the p-value. In this case we're saying that, for something not to be due to chance, there has to be only a 5% probability that it occurred by chance, and therefore a 95% probability of it being an actual result. In the case of a triangle test, we'd expect people to guess correctly about 1/3 of the time, and so, as you noted, once the numbers of correct responses gets to something more like 1/2, it becomes significant. Exactly what that fraction needs to be for it to be significant depends on the desired p-value.

This is called a binomial distribution, by the way, and isn't limited to equally weighted outcomes or true/false outcomes, they just make the math much easier.

Edit: In the hard sciences (or at least in my experience), p<0.05 is generally acceptable for publication of empirical data. p<0.01 is generally desirable and would be accepted for publication pretty much anywhere.

General Homebrew Discussion / Re: First time using Gelatin
« on: Today at 02:13:09 PM »
Just for the hell of it I added some yesterday to a very heavily dry hopped saison with 20% oats. It will be interesting if it can get through that haze.

Gelatin wouldn't be expected to be very effective against protein or polyphenol haze. Just a heads-up in case you don't get what you're looking for (ha!).

General Homebrew Discussion / Re: Dosing thought?
« on: Today at 02:10:03 PM »
top off the base beer to 100 mL again

I'm wondering what that means precisely. If you're tasting from the 100 mL sample, then tracking the concentration gets trickier, but not impossible.

For example, if you make a 1% solution, then drink 45 mL, then top off to 100 mL, then add another 1 mL vodka, you'd be at about a 1.55% solution. Repeat and it's a ~1.85% solution, etc.

I did a cherrywood smoked porter a couple years ago. It had a more conventional porter grain bill, but with 30% cherrywood malt I liked the result.

Yeast and Fermentation / Re: New starter procedure trial
« on: Today at 01:24:30 PM »
Is the foam continuously aerating it as it settles?  Kai has done an experiment with an aquarium pump and sterile filter pushing air through a tube that rests just above the surface (to avoid foaming), and it seems like this would be similar.

That's the hypothesis as I understand it. In which case the DO levels would be much higher than you'd get from simply keeping the headspace purged with air.

FWIW, I use an air pump in conjunction with a stir plate and have found that does give a little boost in cell counts at relatively low stirring speeds.

Alternately, for the lazy a shot of pure O2 at the begining is an option.  In fact, it might be superior for lager yeasts.  Any thoughts on that?

I'd be wary of injecting O2 after the yeast are in suspension. Pure oxygen is pretty toxic.

Of the 40 participants, only 17 (p=0.11) were able to correctly identify the unique beer in the triangle test

Can anyone comment on what a typical threshold for significance is in sensory testing? Any food scientists in the house? p<0.05 seems like a pretty tough standard to me, especially with relatively small sample sizes, and several of these Xbmts have been flirting with the p<0.1 range.

Yeast and Fermentation / Re: Repitching Yeast
« on: Today at 10:47:59 AM »
You can get a decent estimate if you let the yeast fully compact in a mason jar (or something similar).  I'd have to go find the cells/mL estimate that's out there but it should be a better estimate than you could get with fresh slurry.
Can you clarify your statement? I'm not sure I follow the logic here.

If you really let the slurry compact out (i.e. a week stored just above freezing), it'll settle in at more like 3-4 billion/mL. You could then harvest that and get a more precise pitching rate due to a more accurate estimate of cell count. You could also resuspend it in known volumes of beer or water to get a little intuition for what slurries of varying thicknesses look like, in lieu of cell counts.

The Pub / Re: Bud-e
« on: October 05, 2015, 08:50:14 PM »
Damn it, I thought that B-to-the-E stuff was back. Someday...

Yeast and Fermentation / Re: White Labs vs Wyeast Fan Favorites?
« on: October 05, 2015, 10:44:24 AM »
For me that list would go something like 3787, 3522, 1968, 3522, 1272, 1272.

Yeast and Fermentation / Re: New starter procedure trial
« on: October 05, 2015, 10:40:10 AM »
Yet that's what I do 80% of the time.  How would you account for my lack of problems?

Overall good technique and "defense in depth". I met a brewer several years ago who had been brewing excellent beers for years despite not doing what we would consider sanitizing. Just dish soap and hot water. Beer is pretty robust stuff, and acceptable contaminant loads from a flavor stability perspective are high.

Kegging and Bottling / Re: carbonation for 9% ABV beer in bottles
« on: October 05, 2015, 09:13:55 AM »
With respect to a small amount of yeast, for a half-batch (2.75 gal), would that be say, 1/8 of a packet of dry yeast?

Sierra Nevada re-yeasts at 1 million cells/mL, supposedly. For a 2.75 gal batch, that would be about 0.5 g, or 1/20 of a 10.5 g packet.

Yeast and Fermentation / Re: Repitching Yeast
« on: October 04, 2015, 04:40:25 PM »
For what you'd scoop or dump from a fermenter, most likely 1-2 billion/mL. It's really helpful to do a few counts with a given strain, after which you can probably get away with eyeballing it.

You always want to re-pitch as soon as possible. I don't have any problems with storing slurry for a couple weeks under beer, though. After that I'd take a small quantity and grow it back up.

You can also hook it up at serving pressure, shake the bejeezus out of it, and tap it the next day.

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