Malting Barley
Malting is a process which both preserves a grain for longer-term storage than is possible in the raw form, and activates enzymes in the grain that help turn starches into sugars. Malted barley is the source of the sugars (principally maltose) which are fermented into beers and ales. The malting process allows the grain to partially germinate, making the seed's resources available to the brewer.
Malt is germinated grains in which the germination process is then stopped by heat, the process is known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air.
The following process for the malting of barley has been taken from Smith (see bibliography), noting that this information is also available from other sources.
Step One; Steeping the Raw Barley
Step Two: Germinating the Grains
The grains must be germinated in a cool, slightly moist, but well ventilated area to grow the small leaflet inside the grain called an acrospire. This generally takes 2-5 days. The ideal temperature for germination is 64F, or about 18C.The seeds must be kept cool, spread out well and moistened periodically with a little spray mist. The germination process generates heat, which can lead to bacteria or mold growth so the grains must be aerated and turned every few hours in a cool location to avoid infection. Malting is continued until the small leaf (acrospires) within the grain is approximately 80-100% of the length of the grain. Noting that the acrospires are inside the grain, the grain must be split open in order to assess the white leaf that is part of the endosperm and attached to the rootlets. Typically the external portion of the rootlet will be about twice the length of the grain when it is finished.
Traditionally the sprouting would be carried out on a large floor (Markham, p182-185), often in the attic of the malt house. As the grain sprouts, it generates heat, which must be allowed to escape so that the malting grain does not cook itself. The young plants also require carbon dioxide to continue growing. To facilitate this, the malt is turned (scoop it up, flip it over) at regular intervals.
Step Three: Drying the Malt
Once these grains had germinated, the germinated grain is then heated/kilned to stop the germination and preserve the sugars created within the grain. Drying the malt requires a steady temperature of between 90-125F (31-50C). Drying at a higher temperature will destroy the enzymes needed for mashing. Depending on the climate, sun drying is also an option in sunny and dry climates. Although some care is needed, it can be left out in the sun for 2 days, which should be sufficient to dry the malt. A third option is to use a food dehydrator.
The target is a finished moisture content of approximately 10%, which would mean that the finished weight of the grains with their rootlets attached should be close to the total weight of the unmalted grains prior to the steeping process. Therefore the drying process can be ended when the grains plus rootlets weight are back to approximately their original unmalted weight.
Historically, kilning was often carried out in what is essentially a large wood oven or smoker. The malt would be spread out on a false-floor made of hair-cloth, straw mat, or other suitable material, on top of some type of loose material, in order to allow the hot exhaust from the kiln's oven to evenly penetrate the grain. Then a wood fire would be built in the oven, and the malt baked for several hours, and occasionally turned to prevent burning (Markham, pp. 186-190).
Step Four: Finishing the Malt
The last step is to separate the dried, malted grains from the rootlets growing out of them. After the grains are sufficiently dry, the rootlets will simply fall off them with a little agitation. A colander or a screen is used to shake the grains around and separate the dried rootlets.
Malt is germinated grains in which the germination process is then stopped by heat, the process is known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air.
The following process for the malting of barley has been taken from Smith (see bibliography), noting that this information is also available from other sources.
Step One; Steeping the Raw Barley
- The first step in home malting is to steep the barley in water to begin the germination process. Start with a large bucket that can handle the grains plus enough water to float all of the grains. Add water until all of the grains are floating, and let the grains sit in the water for 2 hours.
- The grains are removed from the water and allowed to air out and dry for about 8 hours. This step is important because if the grains are left in the water they will drown and eventually die.
- After the grains have dried for about 8 hours, they are steeped again in a clean batch of water for another two hours, and dried again for 8 hours. This may need to be continued for a third cycle. Within 24 hours of starting, small roots should start to grow from the base of the kernel (called chits). Once 95% of the grains germinated, the cycle of steeping and drying should be ended.
- Approximately 40-45% moisture (water) should have been added to the grains at this point which, assuming the grains initially contained ~9-10% moisture content, would result in a weight gain as follows:
Step Two: Germinating the Grains
The grains must be germinated in a cool, slightly moist, but well ventilated area to grow the small leaflet inside the grain called an acrospire. This generally takes 2-5 days. The ideal temperature for germination is 64F, or about 18C.The seeds must be kept cool, spread out well and moistened periodically with a little spray mist. The germination process generates heat, which can lead to bacteria or mold growth so the grains must be aerated and turned every few hours in a cool location to avoid infection. Malting is continued until the small leaf (acrospires) within the grain is approximately 80-100% of the length of the grain. Noting that the acrospires are inside the grain, the grain must be split open in order to assess the white leaf that is part of the endosperm and attached to the rootlets. Typically the external portion of the rootlet will be about twice the length of the grain when it is finished.
Traditionally the sprouting would be carried out on a large floor (Markham, p182-185), often in the attic of the malt house. As the grain sprouts, it generates heat, which must be allowed to escape so that the malting grain does not cook itself. The young plants also require carbon dioxide to continue growing. To facilitate this, the malt is turned (scoop it up, flip it over) at regular intervals.
Step Three: Drying the Malt
Once these grains had germinated, the germinated grain is then heated/kilned to stop the germination and preserve the sugars created within the grain. Drying the malt requires a steady temperature of between 90-125F (31-50C). Drying at a higher temperature will destroy the enzymes needed for mashing. Depending on the climate, sun drying is also an option in sunny and dry climates. Although some care is needed, it can be left out in the sun for 2 days, which should be sufficient to dry the malt. A third option is to use a food dehydrator.
The target is a finished moisture content of approximately 10%, which would mean that the finished weight of the grains with their rootlets attached should be close to the total weight of the unmalted grains prior to the steeping process. Therefore the drying process can be ended when the grains plus rootlets weight are back to approximately their original unmalted weight.
Historically, kilning was often carried out in what is essentially a large wood oven or smoker. The malt would be spread out on a false-floor made of hair-cloth, straw mat, or other suitable material, on top of some type of loose material, in order to allow the hot exhaust from the kiln's oven to evenly penetrate the grain. Then a wood fire would be built in the oven, and the malt baked for several hours, and occasionally turned to prevent burning (Markham, pp. 186-190).
Step Four: Finishing the Malt
The last step is to separate the dried, malted grains from the rootlets growing out of them. After the grains are sufficiently dry, the rootlets will simply fall off them with a little agitation. A colander or a screen is used to shake the grains around and separate the dried rootlets.
Our Malting Process
Two kilograms of barley grain was sourced from a feed shop for our malting. This ensured that the grain had not been steamed, heated, or treated in any way and therefore increased the chance of the malting actually succeeding. The grain was placed in a bucket of water and allowed to soak for 9 hours then drained - the grain was allowed to dry a little overnight. This cycle was repeated for five days. At this end of this period, little rootlets appeared on the grains.
In order align our work with the traditional method of laying the grains out on the malting floor, the grains were placed on trays and kept moist. During the day the trays were left out on a table in front of a window to obtain a little warmth and light from the sun and then kept in bags at night (to retain the moisture in Canberra’s dry climate), and then on top of a blanket to keep warm (due to the change of season). During the four days the grains were on the trays, the grains were turned over by hand every two to three hours and sprayed lightly with water (except at night where it was moistened then left under cover for the night). Two days into this process, germination was visible on most grains: by the end of the four days, At the end of the four days, the grains were kilned, at a kilning temperature of approximately 33 deg C for 24 hours. The heated grain has a slightly sweet aroma.
The grain will be threshed lightly to remove the roots and stored for use as the malted barley for the wheat beer which will be part of our next entry in the Challenge.
In order align our work with the traditional method of laying the grains out on the malting floor, the grains were placed on trays and kept moist. During the day the trays were left out on a table in front of a window to obtain a little warmth and light from the sun and then kept in bags at night (to retain the moisture in Canberra’s dry climate), and then on top of a blanket to keep warm (due to the change of season). During the four days the grains were on the trays, the grains were turned over by hand every two to three hours and sprayed lightly with water (except at night where it was moistened then left under cover for the night). Two days into this process, germination was visible on most grains: by the end of the four days, At the end of the four days, the grains were kilned, at a kilning temperature of approximately 33 deg C for 24 hours. The heated grain has a slightly sweet aroma.
The grain will be threshed lightly to remove the roots and stored for use as the malted barley for the wheat beer which will be part of our next entry in the Challenge.