Beer Brewing

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Home Malting
Building a Malting Machine
Kiln Drying

Beer brewing has been a hobby for years. My brother and I have checked out different approaches to beer brewing, including home-malting and a semi-automatic brewing installation. In 2001 I founded the AMIV BRÄU , a student brewery for the students union (AMIV) at ETH Zürich.

Home brewing - from scratch

Home Malting

In our effort to brew the all-selfmade beer, we have started out making malt from barley. We checked out different methods using pots, nets, bags, fruit dryers, a hairdryer - just to conclude that malting is a delicate business. We found that if a malting process is to be reproducible, parameters like humidity, temperatures and time spans must be tightly controlled. This lead to the construction of a malting machine and a 'kiln dryer'.

Malting requires the following steps:
The reason why barley is malted is that enzymes are built during the growing process. These enzyms (mainly alpha- and beta-amylase) help cutting starch into simpler sugar molecules during the mashing. Sugar, as opposed to starch, can be fermented by yeast.

A machine for the boring task

As soaking, drying and turning the grains for several days is boring and prone to forgetting, we constructed a machine that does the job. A plastic barrel holds the grains. Holes allow the water to enter and leave the barrel. A motor lets the drum rotate at a slow speed, so the grains are turned at regular intervals. The water level is controlled by electric valves. A floater switch serves as an 'emergency shut-off' for the water to avoid floods and alike. The machine is controlled by a PIC microcontroller with an LCD display. The software allows to adjust the timing of the process.
The machine is filled with barley and when started, works on its own for a week.

raw barley is filled into the drum  reloading the machine
The machine gets refilled with raw barley 

malting machine   malting machine
The machine during a soaking period

malt machine controller  barley after soaking for a week

Left: This box contains a PIC microcontroller and controls the motor and the water valves
Right: Barley grains after a week of soaking and germination

Kiln drying

A typical drying profile starts with a high air flow at roughly 30 degrees Celsius. The temperature slowly rises to 50 degrees after 15 hours. After that a faster increase leads to around 80 degrees. The last four hours are usually at the roasting temperature around 80-110 degrees, depending on the required type of malt.
To get a reproducible malt quality, temperatures must be tighly controlled. Our installation uses an old electric oven that is controlled by a PC software that implements a PID controller. Temperatures are measured with a calibrated PT100 element. The airflow is guaranteed by a vent.

roasted barley  screen shot of the oven controller software
Left: The barley is put into the oven for kiln drying
Right: A PC software controls the temperature curve of the oven. The temperatures are kept within +- 1 degree Celsius of their goal value

malting oven  malting oven - finished
Left: The oven in action. The barley is kept on three hordes made from metal meshes
Right: Roasted barley after the temperature profile is completed

After the roasting, the radices of the grains must be removed. This is done mechanically in a metal box where the grain is spinned quickly by an electrical drill and a paint stirrer.

 brew-ready malt
Finished malt, after the dry radices have been removed