Expert: Spencer W Thomas - 9/4/2007

Question
QUESTION: IS THERE A FORMULA OR WAY TO FIGURE;
THE AMOUNT OF SUGAR, HONEY, BROWN SUGAR, MALT...
THAT WILL BE PROPORTIONATE TO THE HYDROMETER READING ?
IE: HOW MUCH SUGAR TO ADD TO INCREASE EACH INCREMENT , READING, PERCENT ...?

ANSWER: Yes.  What you are looking for is the "extract potential" of your sugar source.  It is often expressed as "points per pound per gallon".  As an example, white sugar has an extract potential of 45 (pt-gal/lb).  That is, if you add one pound of sugar to one gallon of water, you will get a reading of 1.045 on the hydrometer.  The calculation is, with H meaning the hydrometer reading, E the extract potential, W the weight in pounds of sugar, and V the volume in gallons of water:

H = E * W / V

White sugar and brown sugar have about the same extract potential.  Brown is probably a little lower because it contains some moisture.

There is a table of potential extract here: http://hbd.org/uchima/tech/extract.html

For malt, the situation is more complex.  The potential extract is the theoretical maximum, which will never be reached in practice.  You have to multiply it by your mash efficiency, which is a characteristic of your mashing system and process, and which you can only find out by measuring it.  Pro brewers typically get about 80% efficiency.  Homebrewers efficiencies are usually lower, such as 60 or 70%.  

As an example, the extract potential of pale, 2-row malt is 37.  If you get 70% efficiency, your extract potential for pale malt is 0.7*37 or 26.  Thus, mashing one pound of malt to produce 1 gallon of wort would result in wort with a hydrometer reading of 1.026.  

If you want to make a pale ale with an OG of 1.045 in 5 gallons of wort, how much malt would you need to use?  We can turn the above formula around to get

W = V * H / E

or W = 5 * 45 / 26 = 8.7 lbs



---------- FOLLOW-UP ----------

QUESTION: THANKS !,
1 MORE QUESTION :
- IS THE ALCOHOL MOSTLY PRODUCED IN THE AEROBIC OR ANAEROBIC PHASE OF FEMENTATION ,
IE - IN THE PRIMARY OR SECONDARY FERMENTER ?


Answer
Alcohol is produced mostly during anaerobic fermentation.  That is not "secondary" fermentation, though.  The yeast will consume all the oxygen in the wort in a few hours, from which point on the fermentation is anaerobic.

As homebrewers, we rarely do a true "secondary fermentation".  What we call "secondary" is really just an extended phase of primary fermentation, because it is still using the same yeast.  True secondary fermentation happens in beers such as Lambic-style beers and some English stock ales, where another strain of yeast "takes over" and ferments the wort further than the primary strain could have.  Typically these secondary strains produce distinct flavors that are not found in most beers, such as sour, "horse blanket", "musty" and so on.