Malted barley, or malt, is the brewer's preferred grain for making beer. In it's most basic form, it is barley that has been allowed to germinate by soaking the grain in water. This prepares the starches to be converted into fermentable sugars.
Malting may be one of the most fascinating yet least celebrated steps of the brewing process. That is likely because very few brewers still malt their own grain.
Therefore, it is not on the brewery tours that we have come to know and love.
Also, the most interesting part of the process happens on the microscopic level and probably does not make for a very good show. Nevertheless, it is fascinating.
It All Starts With a Good Soak
Malting begins by soaking either two-row or six-row barley. It is dumped into steeping tanks where it spends a couple of days soaking up water.
The barley is then transferred to a huge room where it is aerated, turned regularly, and held at around 60 F. The goal is to encourage the grain to germinate to make it more open to the fermentation process in which the starches are converted to the sugars that become alcohol. At this point, it is called "green malt."
The trick is that you don't want the barley to sprout too much. After about five days of soaking, the grain will want to take root and grow a new plant. Maltsters—the skilled people in charge of the malting process—want to stop the germination process before this happens.
This is done with heat.
Kilning Green Malt
The maltsters kiln, or dry, the green malt by slowly raising the temperature to more than 120 F. The final temperatures vary depending on what kind of malt they want in the end.
No matter the temperature, the result is the same: the growth of the sprouts is stopped.
What is left is a dried barley grain full of sugar, starch, and a particular kind of enzyme called diastase.
It is during this stage where the final beer begins to take its shape. The level of heat that the green malt is subjected to will play a big role in the final style of beer that is produced. It has much to do with determining the color of beer.
- Low temperatures will form the base for pale-colored beers, including pale ales and lagers.
- Increase the temperature a little more and the malt can be used to make amber-colored beers, such as amber ales, Scottish ales, and Oktoberfest.
- At even higher temperatures, the malt will create dark brown beers like brown ales and dunkels.
- The highest temperatures are used to make the darkest, almost black, beers. These include porters and stouts.
To further complicate matters, the finished malt may be roasted after kilning. This is done at very high temperatures in a roaster. Again, the level of roasting will factor into the darkness of the beer as well as the amount of carbonation it has.
During the fermentation stage, a particular strain of yeast is introduced to further define the beer. For instance, pale ales and lagers require almost the same level of kilning.
When you combine this malt with an ale yeast, you get a pale ale. If you were to use lager yeast with the same malt, the result is a lager.
Of course, there are many other factors that go into any beer recipe, including a variety of sugars, adjuncts, and other grains that may be added. Yet, the way the malted barley is produced gets each brew started down it's particular path.
Turning Dried Barley into Beer
After the grain is transferred to the brewery, the brewer will add the grain to hot water, known as "strike water." This will encourage the diastase to convert the starch into simple sugars. Once those sugars are dissolved in the hot water, the brewer will have wort and be ready to start fermentation in order to make beer.