We all know what grains are, how to mash, ferment and distill them, but what is really in a grain, and why don’t spirits by any other grain taste the same?
To begin, a cereal grain is simply the seed of a grass that has been selectively bred over thousands of years to be a viable food crop. Since a seed must be able to survive on its own, grains have everything essential for making a new plant. This is what allows malting to occur. During the malting process, a grain is steeped in water, triggering the seed to germinate, or sprout. In order for this to happen, the grain must expend a great deal of energy, which is provided to it by the starches that it has stored. That being said, starches must be converted into sugars before they can be used by the plant for growth and to make cellular structures. In order to break down the starches, the grain activates a family of enzymes called amylases. These enzymes work to break down starch into simpler sugars, primarily maltose.
When malting a grain, the grain is allowed to sprout only a few inches. This is enough for the grain to activate its amylases, but not enough to significantly decrease starch supplies. Fortunately for brewers and distillers, amylases are relatively stable enzymes with the ability to be stored I the grain after drying. The mashing process takes advantage of these enzymes and steeps crushed grain in hot water in order to dissolve and suspend most of the grain material and allow for amylases and other enzymes to break down the remaining starch in the grain into sugars which can be fermented. These enzymes are less effective and are broken down quickly at higher temperatures, therefore most mashes occur around 150 degrees Fahrenheit.
Now that we have a basic understanding of what a grain is, lets get into some of the chemistry of what I just laid out.
In the image of a grain, the important parts for our purposes are primarily the germ and the endosperm. The germ is the ‘brain’ of the grain, it gives instructions to germinate, produces most of the proteins, and will eventually turn into a plant. The endosperm contains all of the starchy food for the plant that is broken down into sugars. It is worth noting here that when mashing, existing enzymes in the grain are being used to break down the starches, and although this is effective, when a plant is sprouting, there is a great deal more complexity to the process, and it is catered to the individual plant.
The biggest issues that occur during mashing have to do with the grain and starch structure. Starches in dried grains are stored as crystals in the endosperm cells. Each endosperm cell is wrapped in a thin layer of beta glucans. This layer must be broken by heating grains in water. This is the gelatinization process, and the temperature of gelatinization is highly dependent on what kind of grain you are mashing.
Malted barley is gelatinized at temperatures around 150 degrees Fahrenheit. This is coincidentally in a temperature range where the amylase (starch breaking) enzymes are active. This means that the mashing and gelatinization steps can occur simultaneously. In other grains such as corn, the gelatinization temperature range is from 160 to 206, with gelatinization occurring very slowly at the lower end of the spectrum. For this reason, whiskey mashes often employ additional enzymes and add malted barley while heating and cooling the mash, to replenish the denatured enzymes.
What makes different starches have different gelatinization temperatures? The primary factors are the types of endosperm wrapping employed by the grain. Grains with tougher wrapping will be more difficult to get water into and will require higher temperatures to burst the starch packets. Additionally, malting can decrease the gelatinization temperature, as there are enzymes called beta glucanases that break down the endosperm wrappers that the grain produces during the malting process.
Leave a ReplyCancel reply