hist-brewing: Heat effects on SG, Clarity, and FAN

Jerry Harder mastergoodwine at alltel.net
Wed Mar 22 20:11:34 PST 2000

Below is the plane for a new experiment that I
plan on completing in a few weeks.  Any input
and comments would be appreciated.

Master Goodwine /
Jerry J harder


It has been noted by numerous sources, that
during boiling of honey and water
in a mead must, proteins are coagulated and
this process aids in the clearing of
mead.  In specific a recent experiment has shown
that a 20 minute boil is
sufficient to cause the must to become clear
immediately upon cooling.  This
experiment is designed to bracket the minimum
treatment necessary to cause
this effect between specific heat treatment methods.

Secondly, in a past experiment exploring different
sanitation methods, it
discovered that a 20 minute boil reduced the
fermentable nitrogen by nearly
30%.  The fermentable nitrogen in the must
consisted of the natural compounds
of the honey and added di-ammonium phosphate.
 This brings to mind several
questions of practical concern.  First, if it is only the
di-ammonium phosphate
being lost during the boil the obvious solution is to
add the nutrient after the boil.
This experiment is designed to discover whether
the fermentable nitrogen in the
honey is lost during the boil, and to what extent
for different heat treatment
methods.  This has immediate application to
historical brewing discussions
where honey and water are boiled for extended
times, often for times well over
20 minutes.  If the fermentable nitrogen in honey
is stable, it is still a low nutrient
must, but if not, the process would make a must
already too low in nitrogen even
lower.  This is meant as a baseline experiment using
modern honey produced
from modern honey production methods.
Evaluation of nitrogen being added
from the crushing whole hives as done historically
or potential additions from
herbs also boiled in the must is beyond the scope
of this particular experiment
and will be the topic of future experiments.

Also in the previous experiment, it was noticed
that after compensating for water
losses there was a significant loss of specific
gravity points (0.005) in the must.
There is some question as to whether volume
losses were accurately
compensated in the last experiment.  In this
experiment small samples will be
used so that a precise gram balance can be
used to bring the sample back to its
original mass eliminating any error caused by
temperature - volume changes.
This may lead to clearer understanding of what
is to be expected for a final
specific gravity after fermentation, and possibly
a simple test to determine a
portion of the specific gravity that is not part
of the fermentable sugar.


1)  Evaluate different heat treatments on the
post boil clarification of mead must.

2)  Evaluate the effects of heat on fermentable
nitrogen as measured by the
Formol process.

3)  Determine what effects boiling has on
the specific gravity.


250 ml solution at 23 deg. C. and a specific
gravity of 1.101 (24 Brix) would


9 batches + 115 ml for original test gives
2.586 L needed

(2,586)(.264172USGal/L)=0.683 gallons

(0.683 gallons)(8.234lb/gal)(1.101)=6.193 lbs.
quantify needed.

(6.193lb)(.24[Brix])=1.486lb sugar needed.

1.486/0.79[Brix honey]=honey needed=1.88lb.

To make a little extra and arrive at an even unit
measurable by my scale we will
use 2.0 lb. honey and a little reverse engineering:

This is (2.lb honey)(.79)= 1.58 lb. sugar.

1.58/.24=6.58 s. total solution.

6.58-2.0 =4.58 lb. water.


1)  Assemble must by weighing out 4.58 lbs.
water and 2 lbs. honey.

2)  Measure specific gravity and adjust to 24
brix, or a specific gravity of 1.101 if

3)  Measure and record:


4) Measure out units of 250 ml by weight (274.57g).

5)  Bring one unit to a boil and measure the boiling
point.  This is the
temperature during the boiling process.  It should
not change unless
atmospheric pressure or must makeup change.  It
will be used to help determine
boiling point for purposes of timing boil time in
later batches.

6)  Bring unit #1 to 145 deg. F. for 20 minutes,
then move to a water bath to cool.

7)  Bring unit #2 to 175 deg. F. for 15 minutes,
then move to a water bath to cool.

8)  Bring unit #3 to the boiling temperature (that
determined in step 5) and move
to the water bath to cool.

9) Bring unit #4 to the boiling temperature and
begin timing.  Continue to heat
and boil slowly for 10 minutes.  Then remove
to water bath to cool.

10) Bring unit #5 to the boiling temperature
and begin timing.  Continue to heat
and boil slowly for 20 minutes.  Then remove
to water bath to cool.

11) Bring unit #6 to the boiling temperature
and begin timing.  Continue to heat
and boil slowly for 30 minutes.  Then remove
to water bath to cool.

12)  After the units have cooled examine them
to determine which have cleared
and which have not.  Determine between which
two units the transition accrued,
and repeat the process for a treatment in-between.
For example, suppose that a
10 minute boil did not clear but the 20 minute
one did.  Unit #7 should be Boiled
for 15 minutes, and then placed in a water
bath to cool.

13) For unit #8, weigh out 250 ml distilled water:
(250ml)(0.997534g/ml)=249.38g and add sufficient
di-ammonium phosphate for
300g/ml FAN.  This should be:


Measure FAN, boil for 20 minutes, and set to water
bath to cool.

14 For all cases: after cooling, use a syringe, distilled
water and the gram scales
to carefully rinse the boiling vessel and add the rinsed
solution back to the
weighing container.  Be careful to bring the weight
back to the original 274.57
grams. (249.38g in the case of unit #8, the distilled
water - di-ammonium

Carefully measure the following parameters for each:


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