Malting is the process by which the barley grain is made ready for brewing. There are three stages to the malting process:
- Stage 1: Steeping. The barley grain is soaked in water in order to ensure a sufficient moisture level in the previously dried barley grain. This can take anything from 40 to 70 hours depending on the particular brewery and their source of barley. As you saw at the start of this week, the water used in the brewing process has a significant role to play. At Hook Norton, the water used today comes from the same aquifer as that used by brewer John Harris in 1849 in the first fermentations.
- Stage 2: Germination. The soaked barley is transferred into a second vessel for the process of germination in which the grain develops a root, and the enzymes needed to convert starch into sugars are activated.
- Stage 3: Kilning. In this process, the malt is dried within a kiln for storage. To maintain the longevity of the malt, moisture levels and temperature are controlled during kilning to ensure optimal enzyme activity in the brewing process. During this final stage of the malting process, very subtle changes within the malt can occur which impact on the final properties – appearance and flavour – of the finished beer. So for example, in the case of lager malts, these are kilned at lower temperature which results in higher enzyme activity and a paler coloured beer.
When kilning is complete, the barley grains are now known as malt. As you will have seen at the start of the Hook Norton brewing video, the malt is cracked or crushed to break apart the kernels and expose the cotyledon (part of the embryo of the seed), which contains the majority of the starches. This means that it is easier to extract the sugars needed for fermentation in the subsequent process of mashing.