Translation courtesy of google if it helps " muddy " the water
But this seems to summarise it well from Braukaiser
"
In
Abriss der Bierbrauerei, German brewing author Ludwig Narziss defines
Sudhausausbeute (German for brewhouse efficiency) as the ratio between the amount of extract in the boil kettle and the amount of grain that was used [Narziss, 2005]:
Sudhausausbeute = (kettle volume in l * kettle extract in % * kettle specific gravity) / grain mass in kg
Note that this is a different approach for defining efficiency. The reference is not the laboratory extract of the grain, but the total weight of the grain. The latter includes the weight of the husks and other insoluble material. Because of that the the
Sudhausausbeute is also affected by the potential (or laboratory extract) of the malt used. This is also the definition that German home brewers use for efficiency. Thus care needs to be taken when reading efficiency numbers from German sources. While 75% is a very good efficiency number when based on the total grain weight (most grains laboratory extract is about 80% of their weight) it is only a modest efficiency when seen as based on the laboratory extract of the grain."
Sudhausausbeute
The
brewhouse yield is a measure of the effectiveness of the work in the
brewhouse . It describes what proportion of the
malt went into solution during
mashing . All work steps in the brewhouse are included, from
crushing to
beating the
wort after
hop boiling but before
hot break separation .
The extract content and the volume of the cast-out
wort are required as measured values . The
extract content is measured using a
saccharometer (
areometer ,
beer spindle ) at its calibration temperature in °P (degrees Plato, corresponds to % vol ). The wort may have to be cooled. The volume of the
wort is either read off the scale on the calibrated
wort kettle or determined using a calibrated measuring rod.
ATTENTION: The calculation of the brewing yield, which is also called the hot wort yield, should be calculated using the hot wort volume (including the hot trub ) , not the cast-out volume 1) .
The
brewhouse yield A S is calculated as follows
This calculation is not accurate for various reasons. The volume of the wort is determined at almost boiling temperature, but the measuring devices are usually calibrated to 20°C. The cooking pan, on the other hand, expands at high temperatures. Substances were also introduced into the wort from the hops, which falsify the value of the wort quantity. A correction value of 4% is assumed for all of these factors, and the deflection quantity is therefore multiplied by 0.96.
The value read on the saccharometer indicates the percentage by weight of the extract. These must be converted to percentages by volume by multiplying them by the
specific gravity of the
wort .
This gives the following corrected formula for the brewhouse yield:
The
specific weight SG can be roughly calculated (see article
SG ) or read more precisely from the
Plato table . The product of the saccharometer display, specific gravity and expansion correction factor is also summarized there as a
yield factor, so that the formula can be simplified again with the help of the
Plato table :
Example:
23.0 l of wort with 12.0% original wort were produced from a bed of 4 kg of malt. The
brewhouse yield is thus
The values for the
specific gravity (1.04837) or the
yield factor (12.08) can be read from the
Plato table for the extract content of 12.0% wt (saccharometer reading).
The value of the
brewhouse yield in modern breweries is well over 75%. Depending on
the mashing process and malt quality, around 65 to 75% is expected in the home brewing sector.
Other values used to assess the effectiveness of the brewing process are the cold wort yield, the fermenting room yield
and the
overall yield .
Links
1) Brew Recipe Developer Dokumentation DE
I have to say I know where I stand with the definitions used by brewfather summarised by
@doug293cz rather than the above.