Measuring P.P.G. - Home Brew Forums

 Home Brew Forums > Measuring P.P.G.

03-19-2011, 01:00 PM   #1
hector
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Hi there !

I have bought a few pounds of light DME , but I don't know its p.p.g .

Therefore , I did a Test in two different ways to measure that .

1 - I dissolved 30 grams of the Extract in 250 mL of Water . After dissolving

the total Volume was more than 250 mL . I reduced its Temperature to 20C .

My Hydrometer showed then 1.042 .

2 - I dissolved 30 grams of the Extract in 150 mL of Water , then diluted it with Water to 250 mL and

reduced its Temp. to 20C .

My Hydrometer showed this time 1.046 .

Which Result should I accept as the p.p.g of this DME ?

Hector

03-19-2011, 02:05 PM   #2
Hex23
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The latter one would be more accurate in terms of the process you used. Your volumes and weights seem in the right ratio. Is your hydrometer the kind that uses 60F (16C) as reference or is it really for 20C? If it's the former, and you haven't adjusted, then you're real measurement is 1.047. Also make sure you calibrate your hydrometer. What you're doing right now is how I learned my hydro is off by 4 pts. I measured some DME at 1.048. Then I calibrated in water at 60F and it read 1.004. All DME that I am aware of has a listed PPG of 1.044 or 1.045.

03-19-2011, 02:27 PM   #3
ajdelange
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You put 30 grams (30/453.59237 = 0.0661387 pound) of DME in 250 mL of water obtaining 280 grams of solution. You measured the apparent specific gravity as 1.042. This means the density is 1.042*.998203 = 1.04013 grams/cc and the volume of 280 grams of solution is 280/1.04013 = 269.197 cc. This is .269197/3.78541178 = 0.0711143 gal so your solution is 0.0661387/0.0711143= 0.930034 and, as you got 42 points the ppppg =42/0.93 = 45.1613

For comparison, if you made a 10°P solution with pure sucrose (10 grams of sucrose per 100 grams of solution) the SG would be 1.04003, the density, 1.03816, the volume of the solution 96.3245 cc ~ 0.0254462 gal, the pounds of sucrose 0.02205 and the ppppg = 46.16

In the second experiment you dissolved 30 grams DME (0.0661387 pound) in 250 mL (0.066043 gal) made up to 250 mL (0.066043 gal for 1.00145 ppg and measured SG =1.046. Thus the ppppg is 46/1.00145 = 45.9334

So you got 45.2 and 45.9 - very close to one another and to the 46.16 value for pure sucrose. You are to be commended for your skill at reading a hydrometer!

In summary, both methods gave very close to the same answer. As volumes are more difficult to read accurately than a good analytical balance your first method would be preferred if you had an accurate way to measure density. Given the accuracy with which a hydrometer can be read one method is, as you have demonstrated, as good as the other.

03-19-2011, 10:00 PM   #4
hector
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Quote:
 Originally Posted by Hex23 Also make sure you calibrate your hydrometer. What you're doing right now is how I learned my hydro is off by 4 pts. I measured some DME at 1.048. Then I calibrated in water at 60F and it read 1.004. All DME that I am aware of has a listed PPG of 1.044 or 1.045.
I calibrated my Hydrometer in Water at 20C and it showed 1.005 !

So , I think the p.p.g of this Extract should be 41 .

Hector

03-19-2011, 10:50 PM   #5
ajdelange
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No. It's actual extract and it should be about 46. It is interesting that you got two readings right about the right answer with an instrument that is off by 0.005. Something does not compute here.

03-19-2011, 11:00 PM   #6
Hex23
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Quote:
 Originally Posted by ajdelange No. It's actual extract and it should be about 46. It is interesting that you got two readings right about the right answer with an instrument that is off by 0.005. Something does not compute here.
Agree - I've never heard of DME being any anything other than 44 +/-1 PPG.

OP - Did your hydrometer come with instructions that say what temp standard is used, or is it printed on the paper/scale inside the glass? It would actually be worse if it were 60F. If it is on the 60F standard, which is 15.6 C, not 20 C, then it would really be reading a point higher (1.006). I'd check to make sure you are using the right standard anyway. I think most hydrometers use the 60F standard.

You can always just apply a temp correction if you don't want to have to control the sample to the reference temp.

03-19-2011, 11:16 PM   #7
Hex23
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By the way, do you know the brand and type of DME you bought?

03-20-2011, 09:48 AM   #8
hector
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Quote:
 Originally Posted by ajdelange No. It's actual extract and it should be about 46.
According to the Section 3.4 of John Palmer's " How To Brew " ( Online Version ) , p.p.g of DME is about 40-43 .

Hector

03-20-2011, 09:54 AM   #9
hector
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Quote:
 Originally Posted by Hex23 OP - Did your hydrometer come with instructions that say what temp standard is used, or is it printed on the paper/scale inside the glass?
The calibration Temperature of my Hydrometer is 20C and it is printed on

the Scale inside the glass .

Hector

03-20-2011, 10:05 AM   #10
hector
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Quote:
 Originally Posted by Hex23 By the way, do you know the brand and type of DME you bought?
The Seller gave me a sheet of Paper as " Certificate of Analysis " .

It's written on this Paper :

Dried Malt Extract Powder

Colour : Light

pH ( 10% Solution ) : 5.31

Acidity as Lactic Acid : 0.95%

Moisture : 2.44

Reducing Sugar as Maltose : 64.23%

Protein ( Dry Basis ) : 4.2%

Ash : 1.5%

Produced in INDIA

Hector