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Posts: 2
Reply with quote  #1 
Last 3 years (after buying a hand held Brix refractometer) I have investigated how to calcluate brewing parameters such as alcohol content and original gravity, based on readings from the refractometer ens hydrometer. I found out how to calculate the refractometer and hydometer based on alcohol content, sugar content and proteine content. There is a relation between alcohol and sugar during the fermentation process making it possible to calculate Brix end gravity during the fermentation process. I assume Protein content of wort and beer is one of the important factors that influences these calculations. I can fit my calculations with Promash, assuming certain constants for these parameters.
My question therefore is:
Does promash take into account proteine levels of wort and beer and a certain conversion factor for conversion of sugar into alcohol (0.484 according to Balling ? in order to calculate the expected refractometer and hydrometer readings?


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Posts: 531
Reply with quote  #2 
The following (also found in the ProMash help screen) are the references for the Refrac calculations....You may wish to investigate these references further:

Gravity During Fermentation Calculation:

Bergland, Emlington, Rassmussen (BER) (ref: De Clerck).
Balling's OG with (BER) equations substituted for ABW and AE,  then solved for SG. (ref: De Clerck, Bohnam).
RI - A.J. deLange.

%Alc, OG and Residual Extract Calculation:

Bergland, Emlington, Rassmussen (ref: De Clerck).
RI - A.J. deLange.

Brix, Zeiss, RI Conversions:

Brix to RI - A.J. deLange, using data from the CRC Handbook.
RI to Zeiss - Seibert, R.J. "Routine Use of A Programmable Calculator for Computing Alcohol, Real Extract, Original Gravity, and Calories in Beer," American Society of Brewing Chemists (ASBC) Journal (Vo. 38, No. 1 (1980)).

- Jeff

Beer Engineer

Posts: 2
Reply with quote  #3 

Thanks fo the references. I tried to check them, but there is a problem that most of these references are restricted. As home brewer without getting money from selling software I don 't wat to invest in this. What I did find was an answer from you on :


"Yes and on the same note ProMash is the only application to use the full set of equations (IE Bergland, Emlington, Rassmussen for OG + Balling for ferment SG) developed by Louis Bohnam (and myself), specifically for ProMash. Louis and myself spent about 2 months developing these and verifying the results. The other programs use an "annotated" set of equations (which were publically published by Louis and now floating around the web and brewing magazines everywhere) and while the differences can be minor, they are there."


From this I would conclude that your results are kept secret. As you make a living from selling Promash I can understand this, however I am a home brewer interested in how to clearify and make things accessible for the home brewer. Therefore I do not have to bother about commercial aspects. I have developed also a full set of equations in my free time, based only on the basic physics behind the refractometer and hydrometer (relation to sugar, proteine,alcohol and residual content) in combination with the relations between malt as starting point and sugar, proteine and alcohol as result. However I see that proteine concentration in wort and beer for example has a significant influence on the calculated alcohol content and OG using final gravity and refractometer reading as start, as I can directly determine the influence of all constants in my model on the final result. Assuming certain relations I can fit my calculations almost exactly to yours, however with my home brewed beers I find results sometimes significantly deviating from your calculatons (I measured the original gravity and determined alcohol content by destillation as reference). after optimizing my constants, I can make a better fit with my measured results, but I fear that other proteine concentrations than assumed for commercial brewing equippment is the main source fot the deviations. Therefore I am interested in your equations and assumptions to understand what happens,  probably leading to results valuable for both me (and other home brewers) and Promash. however I also understand your pont of view, so you have to decide if you want to pick this up. 



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