Come On In
The malting process can be broken down into three main steps: steeping, germination and kilning. Put simply, they get the barley wet, then allow it to germinate before it's dried in a kiln. The process is certainly a lot more complicated than that would imply, but that's the gist of it.
To kick things off, the barley grain is moistened and aerated in big vats known as "steeping tanks." The barley seed, once wet, begins to germinate. That's the goal here. Once germination begins, the now-sprouting grain is sent to the (wait for it…) germination room.
The grain is kept in this room for about four days under controlled temperatures with regulated humidity and airflow. It's allowed to grow a "chit," which is what maltsters call the beginning of a root system. Plows ensure an even exposure of the grain to surface air—that's what's causing the waves you see in the grain. At this point, the barley is referred to as "green malt," and it undergoes a process called "modification." Inside each barley kernel, stores of starch are released as cell walls break down, allowing the barley to be milled for brewing.
Before and After
On the left is how barley looks on its way into the germination room, and on the right is barley after three days of germination. If you look carefully on the left, you can see a little white chit poking out of each kernel. On the right, that chit has developed into centimeter-long noodle-like appendages.
After about four days in germination, the barley is kilned. Kilning occurs over one day in two stages: drying and curing.
First, for the drying phase, hot air (up to 120 degrees Fahrenheit) is gently pushed through the malt to stop germination without killing the enzymatic potential necessary for brewing.
To cure the malt, the temperature is then gradually raised to almost 200 degrees Fahrenheit. At this point, the malt is almost completely dry, and the its signature flavors have developed. The temperature at which the malt is kilned and for how long dictates the type of malt that is created. Munich malt, for example, is kilned at a higher temperature than the pale malt pictured here.
After kilning, the grain's moisture content is below 10% of its weight. All of that moisture is in the center of the kernel—if it were used for brewing at that stage, the outside of the grain would crumble to dust, while the inside would gum up a brewer's mash—not good for brewing. So the last process of malting is aging; at MillerCoors, the now-malted barley is aged for 21 days. This redistributes the moisture content throughout each barley kernel, perfecting it for brewers.