Messages

16

Yeast and Fermentation / Re: Oxidation during fermentation

« on: January 20, 2011, 12:43:47 pm »

I don't think the production of CO2 drives out most of the CO2 during fermentation. It's the yeast that is consuming it. The rate at which any gas permeates during a membrane is determined by the gas concentration (to be precise partial pressure) on either side of the barrier and the barriers permeability for that gas. You could have 100 psi CO2 on the other side but the O2 diffusion into the vessel is not affected. At least that is my understanding of the mechanisms involved here.

So you should move the beer once fermentation is complete. But don't rush it too much. Let the yeast truly finish the beer and the little O2 that the beer will pick up likely helps its aging process since stong dark beers seem to benefit from a little oxidation, IMO.

Kai

The solubility of oxygen would be affected by the partial pressure of the gases/liquids inside the fermenter.  But you're correct that diffusion of air through the plastic would be occurring from the beginning.

If oxidation from air is the big concern couldn't you just immerse the whole fermenter in a water bath?  Then the diffusion would be much lower (or nil) since the solubility of oxygen in fresh water is 9 ppm at 20 C.

17

Yeast and Fermentation / Re: Oxidation during fermentation

« on: January 20, 2011, 11:31:06 am »

IMO oxidation doesn't really start penetrating into the plastic primary until fermentation starts winding down.  So perhaps 4 to 10 days depending on the beer. 

I'm really hoping to find out timing wise that at what point keeping the beer in the primary becomes noticably oxidized.

18

Yeast and Fermentation / Oxidation during fermentation

« on: January 20, 2011, 10:25:00 am »

My question is this.  How long can you keep a beer in a plastic fermenter before oxidation becomes an issue?  I've left an RIS in the primary(plastic) for a month before, but then again a little oxidation seems somewhat common on those styles after you age them.

3 weeks?  4 weeks?  5 weeks?  I always hear about oxidation in plastic buckets but I never hear about how long it actually takes to develop.

My next batch of pils I may do a side by side comparison using a 2 week primary in plastic for both and then a 3-4 week lager in a glass carboy and plastic bucket.

If its already been done please let me know the results.

19

Yeast and Fermentation / Re: Forced Fermentation Test

« on: January 14, 2011, 05:15:14 am »

That’s how I have been seeing this as well. The “forced ferment test” is also known as “wort stability test” which is a less confusing name. Fast ferment test also works well with the German name for this test: Schnellgaerprobe (literal: fast-ferment-sample).

Consider me edumacated!

20

Ingredients / Re: New bulk grain supplier

« on: January 13, 2011, 11:15:13 am »

Looks like they've had their soft opening.

I asked them about crushing grain.  Here's the reply:

"We will definitely be adding a grain crushing option (8 cents/lb).  We have a professional brewery mill here and it is microadjustable and we usually run it at .034, but we adjust it down for smaller kernel grains (wheat, rye etc.)
 
Look for that option in the next week."

21

Yeast and Fermentation / Re: Forced Fermentation Test

« on: January 13, 2011, 09:21:53 am »

If you mean Fast Ferment Test, then Kai has a good article on his wiki about it...

I think I may have heard it called a Forced Ferment Test somewhere.

There is no optimal yeast to wort ratio. Just keep in mind that too much yeast, more than 5% for example, might be able to skew the results by bringing in too much of a different OG/FG beer. That beer was your starter beer. But you don’t have to worry about that if you re-suspend the yeast sediment with the wort to be tested before you pitch the yeast and keep a little bit for the FFT.

I used the dregs of a quart jar where I had stored a slurry and the amount of yeast ended up being a liitle bit more than I had anticipated.  In the future I will try to get a little more wort to make it easier to obtain the FFT sample.  Grabbing a bunch of the cold break and letting it settle out in a large pitcher works pretty well for getting wort samples and doesn't take away from the final beer.

.

22

Yeast and Fermentation / Forced Fermentation Test

« on: January 13, 2011, 05:48:52 am »

I ran a FFT on a Belgian Dark Strong for 4 days at room temp (68F +/- 2 F)) and tested a gravity of 1.010 from an OG of 1.100.  I used about 300ml of wort to 75ml of Wyeast 1214 slurry.  I only aerated during the first hour of the test.  This is my first time doing an FFT.

My questions are this:  since this is way overpitching, can I really expect the same level of attenuation (90%) out of the batch in the fermenter (the beer is fermenting at room temp under similar levels of oxygenation)?    Is there an optimal yeast to wort ratio for the FFT?

Besides an overabundance of alcohol the FFT sample didn't taste too bad.  What kind of taste difference can I expect from the FFT vs. the final product?  I was hoping for a moderately high dark fruity ester profile but it was quite low, peppery phenolics were off the chart.  There were also very little malty flavors present.

23

The Pub / Beer Lubricated the Rise of Civilization

« on: November 08, 2010, 10:17:11 am »

Interesting Read

http://www.foxnews.com/scitech/2010/11/08/beer-lubricated-rise-civilization-study-suggests/?test=latestnews



I always knew beer made the world go round!

24

General Homebrew Discussion / Re: Big Mistake?

« on: August 27, 2010, 05:52:59 am »

When you buy another bucket go for the larger size (7.9g) that are usually sold for wine making.

Also,  I've had buckets that got bad infections that took a while to clean and sanitize.  After sanitizing with a couple of different chemicals for a long time it was okay.  But it is usually best to play it safe and get a new one.

25

All Grain Brewing / Re: Attenuation of RIS

« on: May 07, 2010, 12:36:23 pm »

I used about 5 lbs less two row and only 1 lb of extract so my OG was 1.113, I then added in 2lbs of sugar after initial fermentation had stopped.

I only used less grain because my mash tun (10g round) will not hold much more than 24 lbs.

26

All Grain Brewing / Re: Questions after first all grain

« on: May 07, 2010, 09:27:23 am »

I usually sparge about a gallon more than what is recommended.  My runoff gravity never goes below the astringency zone and it helps me to pick up a few gravity points.  Checking the runoff gravity is a good way to find out if you can sparge a little more or not.  Off course you will have to boil that much longer to get down to your target volume.

If I am brewing to style and my gravity is too high at the end I usually add water to get the gravity into spec.

27

All Grain Brewing / Re: Attenuation of RIS

« on: May 07, 2010, 03:09:51 am »

How does it taste?

Same recipe as last time?

It tastes pretty good.  It is not the same recipe as last time.  This one is a clone (my take) of Bell's Expedition Stout.

Can you post the recipe? Does it have more unfermentables?

5.5 gallon recipe

23 lb pale 2-row
1 lb flaked barley
1.5 lb roasted barley
1 lb black patent
1 lb 80 L crystal
.5 lb chocolate malt
3.3 lb amber malt extract
2.5 oz Centennial 10% 45 min
1.5 oz Centennial 10% 30 min
.5 oz Centennial 10% 0 min

mash at 150-152

For 5 gallons
At 60% brew house efficiency
OG 1.150
FG 1.038
IBU 105
ABV 14.4

At 50%
OG 1.130
FG 1.033
IBU 115
ABV 12.5


I used less two row and extract.  This was published in Zymurgy in 2003.

28

All Grain Brewing / Re: Attenuation of RIS

« on: May 06, 2010, 01:40:24 am »

I dont know if it will do any good but I pulled maybe a pint of the beer off and added a whole bunch of yeast to it.

A better late than never FFT.

I guess we'll see what happens.

29

All Grain Brewing / Re: Attenuation of RIS

« on: May 05, 2010, 02:55:26 am »

How does it taste?

Same recipe as last time?

It tastes pretty good.  It is not the same recipe as last time.  This one is a clone (my take) of Bell's Expedition Stout.

30

All Grain Brewing / Re: Attenuation of RIS

« on: May 05, 2010, 02:54:19 am »

Have you calibrated your hydrometer lately?

I usually calibrate the low end with water every few months.  It is always reading perfect.  I have never had a reason to doubt it.