The big difference in the methods described here are the protein and saccharification rests taken in the kettle.
Triple decoction mash
This is typified by a part of the mash being pumped into the mash kettle on three separate occasions. There it is kept at a specific temperature before being boiled. In is then returned to the mash tun. The total duration of the process is 4.5 to 5 hours.
Einmaisch teperature is 35 - 38º C. Then the first mash (about a third of the total) is pumped into the mash kettle. This mash should be as thick as possible.
(First Dickmaische.) The temperature in the kettle should rise slowly; at 50º C a 10 minute protein rest can be taken, between 65 and 70º C there is a 15-25 minute saccharification rest; the mash is then brought to the boil and boiled for 45 minutes. The mash is then pumped back into the tun and reunited with the remaining two thirds of the mash. The contents of the tun are constantly stirred, starting before the boiled mash is returned (vormaischen), while the wort is being pumped back and after all the mash is back in the tun (nachmaischen). As a result of the addition of the first boiled wort the temperature of the whole mash is raised to 50-53º C.
After this the second Dickmaische is pumped into the kettle and boiled for 20-30 minutes. (While this is happening there is a protein rest in the mash tun at 50-53º C.) Through the return of the second mash the temperature in the mash tun is raised to 62-65º C.
Then a third mash is pumped into the kettle. This time not a Dickmaische, but a Lautermaische, which is as thin as possible. The Lautermaische is quickly brought to the boil and boiled for 25 minutes. (During this time: the temperature in the mash tun is 62-65º C = saccharification rest.) When the 3rd mash is pumped back into the tun, the temperature rises to 76-78º C (= mashout temperature). Now mashout occurs, that is the complete mash is pumped into the lauter tun.
Sometimes a "Maischrest" is employed. When the mash is pumped back into the tun a remainder is left in the kettle. When the next mash is pumped into the kettle into the boiling-hot Maischrest, as a result of the higher temperature, more unfermentable dextrines are formed than fermentable sugars.
Double decoction mash
Einmaisch is with warm water at 50º C or the Einmaish is cold and then wqarmed to 50º C. The first Dickmaische (about half the total mash) is boiled for up to 30 minutes. After being pumped back the temperature of the whiole mash in the tun rises to about 65º C. Then a second Dickmaische (about one third of the total mash) is drawn off and boiled. When pumped back into the tun the mashout temperature of 75-78º C is reached. When the malt demands it, during both Dickmaische a longer or shorter protein rest and saccharification rest are taken. Double decoction is often used with pale, well-modified malt.
Single decoction mash
There are different ways of performing this method. This is the so-called "Kesselmaisch" [Kettle mash] method.
Mashing occurs in the kettle and the complete mash, after a protein rest, is warmed to the saccharification temperature. Stirring is stopped and the thin (enzyme rich) part of the mash, the so-called "Satz" pumped into the mash tun. The thick remainder is boiled in the kettle and then pumped into the tun with the thin part and kept at saccharification temperature for 30 minutes. The whole mash is then pumped into the kettle and brought to mashout temperature.
The Hochkurz [High fast] mashing method
This is used with very well-modified malt. Einmaisch is at the higher temperature of 62º C (avoiding a protein rest). The first mash is only boiled for a short time - 5 minutes.After pumping back the boiled mash the temperature rises to 72º C. This temperature is maintained for an hour. Then another mash is drawn off and again boiled for just 5 minutes and mashout is at 78º C.
The einmaisch temperature is 37º C. The mash is then added to boiling hot water. The temperature of the mash is so raised to 70º C. The temperatures between are skipped. This method is used with over-modified malt which saccharifies too quickly.
You can mash any way you like. Abläutern, separating the wort from the spent grains, occurs not at normal mashout temperature (76-78º C) but at boiling point. Wort obtained this way needs to be cooled a little and undergo more saccharifcation. To this aim, "cold Satz", a watery malt extract (diastase extract) obtained after einmaschen, is run off earlier in the process. By mixing the Satz and the wort at saccharifcation temperature saccharification takes place.
I'll probably be going back in time for the next installment. To the pre-thermometer time.