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Messages - tomsawyer

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1456
General Homebrew Discussion / Re: What's next?
« on: February 03, 2011, 10:30:30 AM »
My first couple of AG batches were a pain in the butt, but after that it was smooth sailing.  I think it was mostly having the runoff get stuck and not knowing how to deal with it.  Couple of tips:
1) After the runoff starts you can lightly scratch the surface of the grain bed with your spoon, this is called raking and it prevents fines from settling on top and slowing the runoff.

2) If (and when) the runoff slows, just re-stir everything and start it again, catching the first bit in a pitcher until it runs clear again.  Pour that back over the top.

1457
All Grain Brewing / Re: Calcium and Magnesium and their effects on mash pH
« on: February 03, 2011, 08:41:54 AM »
Lennie,  I'm not too inclined to think that its an issue with buffers.  I've been having a discussion with AJ DeLange on mash phosphates and quite frankly, he's taking me to school.  His take is that the phosphate content and buffering capacity is relatively similar for most mashes.  I'd say that Kai's assumption that this is the case is relatively safe.

I suppose the conclusion is that a mash needs no additional phosphate, that the malt releases adequate amounts for use by the yeast?

1458
General Homebrew Discussion / Re: mash or steep?
« on: February 03, 2011, 08:29:55 AM »
A mash includes a steep, but all steeps aren't mashes.  Soaking a pound of specialty grain in 2+gal of 170F water for 20min isn't going to do much in the way of mashing.  I think the advice to teach a version of steeping that is equivalent to a mini-mash, was a good one.  Then you don't necessarily need to worry about whether a grain needs mashed or not, and you're not going to have pH issues that lead to extraction of undesirable components.

1459
General Homebrew Discussion / Re: mash or steep?
« on: February 02, 2011, 11:21:11 AM »
A crystal (something with "cara-") can be steeped since its already had the starch turned to sugar.  A highly roasted grain can be steeped since its mostly there to add color and flavor, its starch has been burnt up to a great degree.  Any malt that has its starch intact (pils, 2-row, pale, Vienna, munich) needs to be mashed to break down the starch to sugar.  You could get some flavor out of it but the starch is liable to cause cloudiness.

1460
General Homebrew Discussion / Fining With SuperKleer
« on: February 02, 2011, 08:44:19 AM »
I know gelatin is the most often used fining agent in beer, but there are a number of other products on the market.  I tried fining a rye APA with Superkleer, a two part product consisting of kieselsol and chitosan.  The negatively charged kieselsol (silica gel) is added to the beer and stirred, then after awhile you add the positively charged chitosan and this results in charge interaction and coagulation.  It seemed to work well on this beer, and it cleared within a few days at room temp (60F right now).  I've used this stuff on my wine before, which is why I had it on hand.  You might be able to just use the chitosan since most of the stuff you want to drop out (protein, yeast) is negatively charged.  I think the kieselsol does help speed the process though.

1461
All Grain Brewing / Re: Calcium and Magnesium and their effects on mash pH
« on: February 02, 2011, 08:33:02 AM »
It'd be interesting to survey various malts to see what a base pH is as well as what sort of variation from batch to batch one might expect.  You certainly wouldn't guess that a 2-row would come in 0.3 pH units lower than a pils based on a color difference of maybe 0.5L.  Wonder whats going on there?  Also interesting that you didn't see the time dependent effect on pH that you reported earlier.  Seems like this malt may have more buffers in it that are holding the pH both steady and lower.  Possibly more phosphate?  If there are different buffering strengths in different malts, then one couldn't generalize about a pH change from a single experiment like this.  I could imagine that barley's phosphate content might vary with the content of the soil and any fertilization that would occur.  Not sure what the agricultural practices are for this grain in the US versus other countries.

1462
All Grain Brewing / Re: First AG batch......
« on: February 01, 2011, 06:07:39 PM »
I always vorlauf a quart or so, and it never really has much of anything in it.  We're talking a teaspoon worth of little chunks.

1463
I have some 10% phosphoric acid and wouldn't mind using it, my initial thought was it would be a good nutrient for the yeast.  Plus it wouldn't bring a flavor contribution, not that lactic does at typical levels.  I've read where over 2ml per gallon is the threshold for lactic flavor perception.

Also read where calcium phosphate becomes less soluble as the temp increases, making its use in mashing more problematic.

1464
Phosphoric is a stronger acid than lactic.  Lactic is a carboxylic acid and doesn't dissociate as completely, its pKa is 3.86.  Phosphoric acid has a pKa of 2.15.  Since this is a log scale, I think it means the phosphoric is 10X more acidic than the lactic.

More importantly, Palmer says that phosphoric acid precipitates out as calcium phosphate, messing up your calcium level.
OK - I have not Googled it, but can you explain to a dumb engineer what pKa is with the acids?

The little chemistry that I had was in another universe, a long long time ago...
 

Just a way to describe how much an acid dissociates at a given pH.  Look up "Henderson Hasselbach equation" for a simple enough formula for the relationship.


1465
Kai, Star San has phosphoric acid in it and when I make it with tap water the stuff gets cloudy.  Presumably this is due to calcium phosphate precipitating, and the pH goes up.  So I think it is entirely possible for this to happen in a mash.  Whether or not this affects the pH, it does affect the calcium level in an unpredictable way.

1466
Phosphoric is a stronger acid than lactic.  Lactic is a carboxylic acid and doesn't dissociate as completely, its pKa is 3.86.  Phosphoric acid has a pKa of 2.15.  Since this is a log scale, I think it means the phosphoric is 10X more acidic than the lactic.

More importantly, Palmer says that phosphoric acid precipitates out as calcium phosphate, messing up your calcium level.

1467
So for a 10lb grist if you need to go from 5.8 to 5.4, you'd need 4ml.

1468
+1 for Kai's recommendation.  I'd add gypsum for calcium and sulfate, and I use lactic acid to bring the pH in the right range.  since you have the pH meter theres no sense in guessing what it'll take, just add the gypsum to the strike water, mash in and then check pH and add acid accordingly.  I'd give it a good stir before each test and only add a ml or two each time.  Be sure you know what the right pH range is for your measurement (room temp vs hot).

1469
All Grain Brewing / Re: Modified batch sparge?
« on: January 30, 2011, 05:20:17 PM »
I always assumed "no-sparge" meant you did a regular mash and just didn't sparge at all.  But you're probably right.

1470
All Grain Brewing / Re: Modified batch sparge?
« on: January 30, 2011, 06:09:25 AM »
My "no-sparge" was like a sparge but without lautering off the first runnings first.  Mash at 2qt/lb, then add another 1qt/lb or so and stir then lauter.  If I skipped the addition of water after the mash I'd get a poorer yield.  2qt/lb would theoretically give you 75% efficiency tops.  I need a MLT that hold 3-4qt/lb instead of 1.5-2qt/lb to do this.

That 80% was a rough estimate, then again I use the same estimate for my regular batch sparge and typically get 75-85% depending on my mash schedule.  What I have noticed is that a mashout or near mashout where I raise the temp into the high 150's to high 160's, seems to add a good 5% or more on top of a normal single infusion at 150F.  I was surprised at this initially but it seems to be a consistent thing.  Its making my FG just a touch higher though so I am using it in selected situations.

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