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Messages - a10t2

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The Pub / Re: Science Friday on Beer
« on: December 07, 2010, 09:56:14 PM »
Makes you wonder what the experts in other fields think of the interviews *you* find interesting, eh?

Questions about the forum? / Re: View poll results?
« on: December 07, 2010, 07:13:06 PM »
Good to know, thanks. It should have occurred to me to look at the poll creation options before asking.

Questions about the forum? / View poll results?
« on: December 07, 2010, 05:47:53 PM »
Hopefully this is just a checkbox an admin can set...

Anyone know if SMF allows you to view the results of a poll without voting? It's a handy little link to have on topics with polls. Just a thought.

Yeast and Fermentation / Re: 1.022 versus on 1.016 on an oatmeal stout
« on: December 04, 2010, 09:21:46 AM »
Was this all-grain? What's the grist like? Oats will add more unfermentables than an equivalent quantity of barley. Is there anything else (lactose, large amount of crystal malt) that would boost the FG?

At 9 days it's possible it isn't done yet. If you can I'd move it to ~70°F and rouse the yeast a few times over the next several days. Check your hydrometer calibration and temperature correction too.

General Homebrew Discussion / Re: Recipe software for MACs
« on: December 03, 2010, 03:40:55 PM »
I think I've at least tried them all. BeerTools Pro is by far my favorite.

Yeast and Fermentation / Re: A couple questions on starters
« on: December 03, 2010, 11:50:22 AM »
I'm not a microbiologist, but, do yeast produce a significant amount of CO2 during aerobic metabolism?

Yes, it's actually the same respiration mechanism as nearly every other aerobic species, including us (the Krebs Cycle). The net reaction for glucose is:

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Yeast and Fermentation / Re: A couple questions on starters
« on: December 03, 2010, 10:05:18 AM »
I'm not in agreement with Denny on the starter gravity.  In talking with Chris White (White Labs) many years ago, he said they culture their yeast using a much lower gravity wort.  He indicated about 1.020, but I see that in his new yeast book, he mentions 1.030 as a prefered starter gravity.  The issue of the Crabtree Effect is more pronounced when you increase the wort gravity, which diverts some yeast metabolic effort into alcohol production instead of yeast mass growth.

AFAIK all the yeast suppliers culture at <1°P (1.004) to avoid the Crabtree Effect entirely. The only reason that isn't a viable approach (pardon the pun) for most brewers is that you need to be able to add precise quantities of wort, and remove precise quantities of alcohol, continually through the entire culturing phase.

Martin's comment about keeping the flask headspace purged with air makes a lot of sense to me.  I would think that even with foil or foam plug you would otherwise tend to have a nice blanket of CO2 on top of the liquid.

I did a sort of one-off experiment to see if that was the case, and it seems that you do get more growth with foil (or foam, presumably) than with an airlock. So I believe that diffusion is able to carry at least some O2 into the headspace to replace CO2.

Aeration and Yeast Starters

The Pub / Re: What's the Weather Like Where You Are?
« on: December 02, 2010, 10:23:57 PM »
I actually live in the caldera of a volcano, but at least it's dormant.

The Pub / Re: What's the Weather Like Where You Are?
« on: December 02, 2010, 09:05:43 AM »
19°F currently, high of 27°F today. Three feet on the ground, and there's supposed to be another 4-8" by the weekend. Days are beautiful, clear blue skies, and it snows almost every night. (We make our own weather.) Highs for the weekend are supposed to be right around freezing, so unless the snow is bad I'm going to get in my last homebrew for the season. The last time it was above freezing was Nov 15. So a really mild winter so far.

And no, I wouldn't trade it for Hawai'i.

General Homebrew Discussion / Re: 32 Oz EZ Cap Bottles
« on: December 02, 2010, 08:58:30 AM »
It won't be quite correct due to the increase in solubility from head pressure, but you can just take a weighted average of the difference between the volumes and subtract it from the difference between the initial and saturation pressures, and get really close. So for example, if you have 32 fl oz of beer at 2.4 vol and 41°F (~1.4 vol saturation) and pour out 12 fl oz, the remaining 20 fl oz will have:

1.4 + (20/32)(2.4 - 1.4) ~= 2.0 vol

I've also always seen a 4% contraction.

Ingredients / Re: Maris Otter -- which one do you prefer and why?
« on: December 01, 2010, 11:24:48 AM »
My favorite is Thomas Fawcett. The LHBS switched to Munton's and I wasn't really satisfied with that so I had to start mail-ordering TF. The Munton's kernels were smaller and it just seemed less flavorful overall. I used Crisp once and it was good too - I'm not sure I could tell the difference between it and TF.

Equipment and Software / Re: stir plate alternative?
« on: December 01, 2010, 11:21:36 AM »
Something even easier to build would be a shaker table. They're used in labs all the time. Just a motor with an off-axis weight, and some kind of shock dampening between the table and the base so that the noise doesn't drive you crazy.

At the homebrew scale, the easiest/cheapest thing to do is probably to use an aquarium pump and inline filter.

All Grain Brewing / Re: Water Profile
« on: December 01, 2010, 11:13:16 AM »
Unless otherwise noted, hardness and alkalinity are always given as ppm as CaCO3 here in the US.

That's probably true. The only reason it was on my mind is that I just got the report from the local utility and it was in mEq/L - I'd assume they just read the value from their testing equipment and don't bother to convert.

General Homebrew Discussion / Re: Is it done?
« on: November 30, 2010, 07:57:08 AM »
Will do. This first batch LHBS talked me into a bucket. Next batch will be in a carboy so I can see what's going on. I don't like the idea of pulling the lid on it.......

Just to play devil's advocate, how would a carboy change that? You still have to open it to take readings and to transfer.

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