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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  Questions - I ("A.J deLange")
  Questions II ("A.J deLange")
  Re: pH stuff (Kai Troester)


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Date: Fri, 03 Oct 2008 10:46:24 -0400
From: "A.J deLange" <ajdel at cox.net>
Subject: Questions - I

Lots of questions - almost like the old days.

1: Are my postings too heavy for this forum? Yes and no I think. Yes, 
they will be over the heads of some, a small fraction of whom will 
resolve that some day they will not be over their heads. Those are the 
ones I am after. They are the ones that will eventually get the most out 
of HBD. OTOH there are some here who are familiar with these concepts 
and techniques because they work (or have worked) in the sciences or a 
related field or are students in some related field. For them these 
posts should not be over the top.

E0 is the reference potential of a pH electrode i.e. the voltage it 
produces under a standard set of conditions. The goal for a modern pH 
electrode is that it produce 0 mV in a pH 7 solution at 20C. None do 
exactly this and that is one of the reasons a calibration with buffers 
must be done. R is the universal gas constant and F is the Faraday 
constant. RT/F  (T is temperature in Kelvins) is the "slope" of 
electrode which should be about 57 mV per unit of pH at  room 
temperatures (but, again, it never is exactly which is the other reason 
for calibration).

2:  How far off is the Brix/Balling/Plato scale given that it is based 
on sucrose and wort isn't? I don't really know the answer to that 
because the sugar spectra of worts differ dramatically and it is very 
difficult to get Plato-type data on other sugars. Anyone who has opened 
a package of DME on a humid day will understand why (it picks up water 
very fast becoming a gooey mess which would be very difficult to weigh). 
This is why sucrose was chosen - it can be handled relatively easily. 
Another thing to keep in mind is that what we have here is a standard 
i.e. the absolute accuracy is not so important as that everyone get the 
same numbers under identical conditions which allows interfacility, 
inter brew etc. comparison. I often site the FAA's practice of making 
everyone set his altimeter to 29.92 above 18,000 feet. No one is 
actually flying at the altitude indicated by his altimeter but everyone 
whose altimeter reads 30,000 feet is at the same altitude (which is very 
probably not 30,000 feet) and that's what counts. Nonetheless in every 
experiment I have done with other sugars (including some dextrines and 
even starches) the agreement to sucrose is surprisingly close.

3. "How does one get a mash sample down to room temp is a reasonable 
length of time...?" I dip it into a tiny saucepan (holds perhaps half a 
cup) which I swiped from my wife's kitchen. This I lower into a sink 
with an inch or two of cold water in it and let it sit for a few minutes 
stirring it from time to time. I don't always wait until it hits exactly 
20 C but alway record the temperature at which the pH measurement was 
actually made.

4. "Should I build water from the ground up...?" This is a philosophical 
question which has been discussed endlessly. When I first joined HBD 
years ago it was a hot topic with ion profiles for various cities and 
recipies for formulating them being posted frequently. One thing to 
think about is the case where you decide to brew a Munich Helles with 
genuine Munich water and so go to considerable trouble to get carbonate 
to dissolve (next question) only to have to remove it when you soften 
the water as required for a Helles. Why put it in in the first place? 
Many situations are like this. The trend these days seems to be to get 
the mash pH in the right region and add salts which are not related to 
mash pH shift to taste.

5. How much pH shift before the effects of it are noticeable in the 
beer? Only you can answer that question. Proper mash pH is required for 
most efficient enzyme utilization. This may be important to a commercial 
brewer for whom a percent or 2 difference in mash efficicency translates 
into railroad cars of malt over a relatively short period of time but 
for a homebrewer it is a matter of a couple of dollars more or less. Who 
says that a beer from a less efficient mash may not be a better tasting 
beer? Experiment!

6. "How should I convince the minerals that they should stay in 
solution?" Getting them to dissolve is the first problem and the way to 
solve it is to use acid. This can be in the form of a mineral 
(hyrochloric or sulfuric) acid but I do not recommend those as they are 
potentially dangerous and getting them in food grade is likely to be 
difficult. That leaves carbonic acid, i.e. bubble (use a carbonating 
stone or airstone) CO2 through the water after you have suspended the 
salts. This takes a long time and a lot of CO2. If the salts want to 
come out of solution in the hot liquor tank (a likely place) they will 
but they probably did that at the brewery in Munich too. Again, why put 
them in in these cases?

 ... continued in next post


Return to table of contents


Date: Fri, 03 Oct 2008 10:47:28 -0400
From: "A.J deLange" <ajdel at cox.net>
Subject: Questions II

7. "...when should I end my sparge?" The usual wisdom is to terminate 
when the pH approaches 6 and that's probably as good a way as any to 
determine when to quit. If you've done things right the gravity of the 
runoff should be 2 - 4 P at this point. Think about what 4 P means. A 
liter of runoff weighs about a killogram 4% of which (40 grams - an Oz 
and a bit) is sugar. Do you want to risk husk tannin extraction for that 
amount of sugar? I have found by experience with my system that the 
kettle is about full when the runoff hits about 3 P with the pH below 6 
so my criterion is to stop collection when the kettle is full to a given 
level. I still do gravity (with a hydrometer) and pH checks though.

8. Therminator:  Plate chillers are FM. The downside is that you can't 
look inside them to see if they are clean unless you take them apart and 
you can't take a Therminator apart. Go to Blickman Engineering's website 
for data on performance (i.e. how much you can chill how fast at what 
cooling water requirement). I think you will find the unit more than 
adequate for most homebrewing applications (well beyond 5 gal batches).

9. "Why does ProMash provide a calibration adjustment that recommends a 
4% difference between Brix and Plato?" I am puzzled by this too. To get 
a handle on what the practical differences between the scales may be I 
made a 10% (i.e. 10 Brix, 10 Plato) sucrose solution (tare beaker with 
stirbar, add 5 grams sucrose, add water to 50 grams, stir) and 
programmed my density meter to read both Brix and Plato. To my surprise 
the meter indicated 10.00 Brix and 10.00 Plato. The surprise was not 
that they read the same - I expected that- but that I was able to hit 
the target spot on. As a further check I consulted the ASBC tables which 
indicate specific gravity for 10.000 Plato of 1.04003 and that's exactly 
what the meter read.


Return to table of contents


Date: Fri, 03 Oct 2008 12:41:28 -0400
From: Kai Troester <kai at braukaiser.com>
Subject: Re: pH stuff

> Ok I have allot of questions about technique. How does one get a mash
> sample down to room temp in a reasonable amount of time in order to
> make salt/acid additions?

I used to use a large stainless steel bowl to cool down a small  
sample. Now I just keep a small dish in the freezer and take it out  
when I need to cool a  sample

> Because I use R.O. water should I be building water from the ground up
> based on the brewing region of the style in preperation for brewing instead
> of adding minerals to the boil kettle?

Build your water before adding it to the mash. But don't get to hung  
up on the regional water profiles. Many breweries treat the water and  
as a result of that don't use the water profile that is reported for  
that region. When I build water I pay attention to these parameters:

Calcium should be above 50 ppm
Residual alkalinity (balance between Alkalinity and Ca/Mg) should  
match the color of the beer that is brewed.
Sulphates should be low or high depending on the desire to emphazise  
hops or not.

John Palmer's How To Brew has a nice table about the desired levels of  
various minerals.

I add the salts to the water. Chalk doesn't readily dissolve, but it  
stays in suspension long enough that it is not left behind in the pot  
when I add the water to the mash. If you get the residual alkalinity  
right, you should not have to adjust the mash but it is always a good  
idea to check the pH. If adjustments are necessary add chalk or acid  
(I like to use acid malt). And note that so you can do that ahead of  
time next time you brew that recipe.

Kai








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