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Messages - punatic

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3946
General Homebrew Discussion / Re: how do you make a yeast starter?
« on: February 14, 2011, 08:58:15 AM »


Give him some chin whiskers and he looks a lot like Tom... ;)

3947
Yeast and Fermentation / Re: My first yeast starter - questions!
« on: February 14, 2011, 12:56:39 AM »
OK - rule of thumb 1 lb of DME added to 1 gallon of water will give you a specific gravity of 1.045

1 lb DME = 1 lb
1 gal water = 8.34 lb
1 lb DME + 1gal water = 9.34 lb

9.34 lb / Vwort = 1.045 x (8.34 lb/gallon)
9.34 lb/ Vwort = 8.715 lb/gallon
9.34lb / (8.715 lb/gallon) = Vwort = 1.072 gallon
Vdme = Vwort - Vwater
Vdme = 1.072 gallon - 1.000 gallon = 0.072 gallon
density of DME = 1 lb / 0.072 gallons = 13.89 lb/gallon
(13.89 lb/gallon) x (1 gallon / 16cup ) x (16 wt.oz / 1 lb) = 13.89 wt.oz. / cup
Specific Gravity of DME = (13.89 lb/gallon) / (8.34lb/gallon) = 1.665

Recall - Specific gravity can be expressed as g/mL 
therefore DME density = 1.665 g/mL
More dense than the 1.6 g/mL I used in my previous calculations

3948
Yeast and Fermentation / Re: My first yeast starter - questions!
« on: February 13, 2011, 10:04:31 PM »
1 cup DME = 1cup x 8oz/cup x 29.57mL/oz x 1.6g/mL = 378.5g DME

Obviously there's a lot of variability, but a cup of DME is ~150 g.

It appears that it's just not his day... ;)

Hey you guys liked the 1.6g/mL for DME  figure just fine when I used it here:
How Do you Make a Yeast Starter?

Also, 1 cup of water weighs 236.7g 
1cup x 8oz/cup x 29.57mL/oz x 1g/mL = 236.7g

So you're saying your cup of DME only weighs 2/3 as much as cup of water?
If I were you I'd take that DME back to the store and get a refund.   ::)

3949
The Pub / Re: Beer drinking and brewing music
« on: February 13, 2011, 09:31:47 PM »
This popped up after the Voodoo Chile video you linked to above.

Tallan Latz

Do you suppose he was named after the spaceship on Farscape (Moya's son)?

Hey, the chicks dig him...

3950
The Pub / Re: Beer drinking and brewing music
« on: February 13, 2011, 08:37:18 PM »
I was fortunate enough to see Stevie Ray Vaughn & Double Trouble at the Bob Carr Auditorium in Orlando in the mid 80s.  I knew of him from his work on David Bowie's Let's Dance and I was dating a lady who knew him from the clubs in Texas.

She said, "You know that guy on Let's Dance that you like so much and think sounds like Hendrix?  He's at the Bob Carr tonight.  Would you take me to see him?"

Who am I to say no to a beautiful Texican?  It was a memorable evening to be sure!

3951
Yeast and Fermentation / Re: My first yeast starter - questions!
« on: February 13, 2011, 08:18:59 PM »
I think the sediment you are seeing is mostly trub.  Yeast sediment tends to be "dusty" when disturbed.  The yeast often appears as a thin layer of lighter colored sediment on top of the darker trub sediment on the bottom of the fermentation vessel.

If it were me, I would make a new yeast starter from scratch, using 100g of DME to 1 liter of water (1/4 cup DME to 1 quart of water) and pitch a new yeast culture.  
Or better still 1/2 cup DME to 1/2 gallon of water.

IMHO - Replacing a starter is less expensive than replacing a batch of beer that has off-flavors.

If you should decide to use what you have, storing it in a dark, room-temperature place for a day or two is good.  Storing it in the fridge will cause a longer lag time when you pitch it into the wort.  For more than a day or two - the fridge is the way to go.

3952
The Pub / Re: MIT grad's invention turns brewery waste to fuel
« on: February 13, 2011, 07:52:17 PM »
Wait, you mean you could make fuel from the spent grains and use that to make more beer...... it could brew itself! 8)

(I know, the numbers won't, and can't work that way, but the thought is interesting......)



A perpetual motion/brewing machine!  I like the way you think.  :)

3953
Yeast and Fermentation / Re: My first yeast starter - questions!
« on: February 13, 2011, 07:10:42 PM »

prepare a starter is to combine about 4 cups of water with 1 cup of DME, boil for 10-15 minutes and cool to pitching temp.

Well, I followed his advice to the letter but my starter isn't doing a hell of a lot!

4 cups of water plus 1 cup of DME gave your starter wort a original gravity of 1.120 
BEFORE you boiled it.
Boiling removed water and increased the original gravity of the starter wort even higher.

I suspect your starter yeast is suffering from high gravity shock.
What numbers are you using to calculate this?  Working backwards, it looks like you're estimating a cup of DME to weight 11 oz or the water volume is off by half.  Granulated sugar is closer to 7 oz, in my experience a cup of DME is less, about 5.5 - 6 oz (there's variability).  I figure this starter would be about 1.065 pre-boil, more after.  It's still too high though.  A half cup of DME in a quart would be better for the starter.

But weighing is better than volume measurements, I use DME equaling 8-10% of the water weight.

Pre-boil Specific Gravity calculations:

Densities measured at STP
Water has a density of 1.000 g/mL
DME has a density of 1.6 g/mL
1 cup = 8 fluid oz.
1 fluid ounce = 29.57 mL

1 cup DME = 1cup x 8oz/cup x 29.57mL/oz x 1.6g/mL = 378.5g DME 

4 cups water = 4cup x 8oz/cup x 29.57mL/oz x 1.0g/mL = 946.2g water

5 cups solution = 378.5g DME + 946.2g water = 1324.7g wort

5 cups solution = 5 cups x 8oz/cup x 29.57mL/oz = 1182.8 mL wort

Density = 1324.7g / 1182.8mL = 1.120g/mL

Specific Gravity = (1.120g/mL) / (1.000g/mL) = 1.120


3954
The Pub / Re: MIT grad's invention turns brewery waste to fuel
« on: February 13, 2011, 06:24:32 PM »
Anaerobic digesters have been used for wastewater sludge digestion for decades.  Much of the methane produced is used to heat the digestion process, particularly in cold climates like Vermont.

I suspect the 200 cfm is the maximum biogas output rating, not the nominal output.  It would be interesting to know what percentage of the biogas is methane, and how they dispose of the waste sludge generated by the digester.

You'd have to brew a lot to make a home model feasible.

3955
Yeast and Fermentation / Re: My first yeast starter - questions!
« on: February 13, 2011, 04:38:12 PM »
prepare a starter is to combine about 4 cups of water with 1 cup of DME, boil for 10-15 minutes and cool to pitching temp.

Well, I followed his advice to the letter but my starter isn't doing a hell of a lot! 

4 cups of water plus 1 cup of DME gave your starter wort a original gravity of 1.120 
BEFORE you boiled it.
Boiling removed water and increased the original gravity of the starter wort even higher.

I suspect your starter yeast is suffering from high gravity shock.

3956
Yeast and Fermentation / Re: Please help me identify this organism.
« on: February 13, 2011, 04:18:59 PM »
I found this picture here:
A 6 - 7 day - old Trichoderma viride mold culture grown on malt extract agar

It looks like it could be a more mature version of your culture.


3957
General Homebrew Discussion / Re: how do you make a yeast starter?
« on: February 13, 2011, 03:41:07 PM »
Is boiling the starter wort for sterilization or hot break, or neither/both/something else?

I used 10% cause it's easy and in the ballpark.

3958
General Homebrew Discussion / Re: how do you make a yeast starter?
« on: February 13, 2011, 01:33:22 PM »
Which is a good Specific Gravity for a beer yeast starter

Right, that's what I was saying.  ;D

Hey, the boards were a bit slow this morning, so I figured I'd stir it up a bit...   ;)

3959
The Pub / Re: Heat Wave?
« on: February 13, 2011, 01:02:10 PM »
I'd rather wear layers than not be able to take enough layers off and still be hot.

That's exactly why I live here...   no layers needed to be added or removed.  65⁰ F - 78⁰F 

BTW - cool signature  ;)

3960
General Homebrew Discussion / Re: how do you make a yeast starter?
« on: February 13, 2011, 12:20:34 PM »
Oops... I went back and did some math.  My "before my Sunday morning coffee" estimation of a starter O.G. of 1.100 was way off.  100 g of solids dissolved in a 1 L solution does have a Specific Gravity of 1.100, but that's not whats going on here...

Assume:
Densities measured at STP
Water has a density of 1.0 g/mL
DME has a density of 1.6 g/mL
100 g of DME = 62.5 mL

If you add 100 g of DME to 1000 mL (1L) of water the mass of the solution is now 1100 g.
The volume of the solution is now 1062.5 mL.
The density of the new solution is 1100 g /1062.5 mL  = 1.0353 g/mL

Specific Gravity is the (unitless) ratio of the density of a solution divided by the density of water:
Specific Gravity = (1.0353 g/mL) / (1.0000 g/mL) = 1.0353

If 10% of the volume of water is lost during the 10 minute boil (assume no solids are lost during the boil)
The after-boil volume is 1062.5 mL - 106.2 mL = 956.3 mL
The after-boil mass of the solution is  1100 g - 106.2 g = 993.8 g
After-boil density = 993.8 g / 956.3 mL = 1.0392 g/mL

After-boil Specific Gravity = (1.0392 g/mL) / (1.0000 g/mL) = 1.0392

Which is a good Specific Gravity for a beer yeast starter




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