>> So far in our journey in the brewing process, we've malted our barley, and we have kilned
the malt. The next step is going to be mashing and lautering. The mashing process we're going
to let the enzymes and the malt break the starch and the sugar, most often maltose.
There's two forms of mashing: infusion and decoction. In infusion we mix the malt with
the water, and we heat it up together. It's a newer process that really became available
when we had very accurate thermometers. In decoction what we do is take a portion of
the mash and boil it, take that boiled content and put it back in with the rest of the mash
to raise the temperature. This is an ancient process that was used whenever there were
not accurate thermometers. Both of these are used to get the mash up to a certain temperature,
but not boiling. What we want is our enzymes to be active. There are specific temperatures
where these enzymes will be active. Once we have exceeded this temperature, the enzyme
is denatured and no longer active.
When we start the mashing process, we start with malt. The malt is still in granular form,
in its grain, so we first need to break that open to increase the surface tension. So we're
going to mill the grain to get a grist. The grist is then mixed with water, and the water
is then heated up to a certain temperature. There are several enzymatic rests. The enzymatic
rests are temperatures where we get the most enzymatic activity. There is the beta-glucanase
rest, the protease rest, and the amylose rest: either the beta-amylose rest or the alpha-amylose
rest. The beta-glucanase rest is actually a enzyme that breaks down beta linkages in
cellulose. This enables the starch to come out of the cell walls. You have to be careful
with this rest because if you break down the cellulose too much, it'll actually interfere
with the filtering process and the lautering step. The proteinase rest degrades proteins,
giving free amino acids and other smaller protein molecules. We have to be careful here
because if too much free amino acid in the wort will actually cause off flavors. We also
want to have smaller proteins for a developed head, but if we break down the proteins too
much, it'll also cause clouding.
The amylose rest, both the beta- and alpha-amylose rest are the most important. It's the amylose
enzymes that are going to convert the starch into sugar. The beta-amylose rest is for the
beta-amylose enzyme. This enzyme will break down amylose and amylopectin by starting at
a non-reducing end and then breaking it glucose by glucose. The alpha-amylose rest more or
less takes the larger starch and snips it into smaller pieces. Depending on where we
set the temperature, either at a optimal beta-amylose rest or an alpha-amylose rest, will change
the overall flavor and texture of the beer. If we have a lower temperature, we're going
to favor a beta-amylose rest. This is going to give us a crisper, less malty beer. If
we have a slightly higher temperature at the alpha-amylose, we're going to leave smaller
dextrin molecules together that give us a malty flavor and a more full-bodied beer.
So once we've completed the enzymatic rests, we then want to get to the lautering process.
Before we get that, what we do is a mash out. Remember we've set our temperatures to optimize
the enzymatic activity, but at these lower temperatures the wort is still very thick,
and what we want to do is make it less viscous. So we raise the temperature, or mash out.
So we'll raise the temperature up and prepare for the lautering step.
Now lautering is just the process where we're going to separate our liquid wort from our
residual grain. Usually this is done by sparging. We sparge by putting a little extra water
into the mixture. This extracts out more of the fermentable sugars, but we have to be
careful. There are tannins in the grain husks. If we extract too many tannins, we can get
a very bitter or astringic beer. At the end of lautering, what you have is you have your
spent grain and you have your liquid wort. It's our liquid wort that we're going to take
to the next stage of the brewing process: boiling and hopping. The main step in the
mashing and lautering phase is to convert starch into simple sugars that can be digested
by the yeast and turned into ethanol.