In an earlier article we discussed what is malt and how it is important in the brewing of beer, now we will look in a bit more detail at what it is that makes malt very different from the barley that it is made from.
One of the main contributions that malt makes to the brewing process is of course starch. However, as yeast finds it difficult to break starch down into simple sugars the starch would not be of much use to the brewer without enzymes. Enzymes are proteins present in every living organism and have an extremely important function, which is they greatly increase the rate of a biochemical reaction. So for example an enzyme will typically increase the rate of a reaction by a factor of 10 raised to the power of 10. To put this into perspective an enzyme catalysed reaction that takes 1 second will take 300 years without the enzyme!
If you remember, from the earlier what is malt article, during germination barley utilizes the starch, contained within the grain, as a source of energy to drive the biochemical reactions that take place as the grain grows into a plant. But starch is a complex storage carbohydrate and so needs to be broken down into simple sugars before it can be utilized by the grain. Therefore the germinating barley grain synthesizes enzymes that will facilitate the rapid breakdown of the starch into simple sugars. As the grain germinates the embryo produces a hormone called gibberellic acid which migrates to a layer of cells around the endosperm known as the aluerone layer triggering these cells to synthesize a number of different enzymes. There are various enzymes involved in the breakdown of the starch in the endosperm but they can be grouped into 3 main enzyme types which are:
- Cell wall degrading enzymes
- Protein degrading enzymes
- Starch degrading enzymes
These enzymes must work together to achieve the breakdown of starch to sugar. Within the endosperm there are cells, which contain the starch granules. The cell wall degrading enzymes act on the cell walls breaking them down to reveal something known as the protein matrix. It is the protein matrix that contains the starch granules. Therefore for the starch granules to be broken down into simple sugars the protein matrix must first be degraded. Finally with the cell walls and protein matrix broken down the starch degrading enzymes can get to work on the starch.
All these reactions occur during the germination of the grain and this is what the maltster seeks to control during the malting process to provide the brewer with all that they need to brew great beer. In the next part of this article we will take a closer look inside a maltings and discuss how malt is made in practice.