Malting begins with steeping (soaking) barley in water, increasing the moisture level from around 12 per cent to 40-45 per cent, prompting germination. Each grain contains numerous ‘packets’ of starch enclosed within cell walls, and germination triggers the release of enzymes that break down these walls and enter the starch (this is vital when subsequently producing new make spirit, as enzymes break the starch down into sugars during mashing).
Following germination the barley is dried using heat from a kiln. Peat can also be added to the kiln, creating smoke which is absorbed by the barley, essentially while the husk retains surface moisture. Kilning continues drying the barley to a moisture level of around five per cent, when it can be stored safely (without developing mould).
Wherever steeping is undertaken it generally takes around two days. After steeping, commercial maltings have various high-tech options. However, with floor maltings, as at Bowmore, Balvenie, Highland Park, Kilchoman, Laphroaig and Springbank, there’s only one option: tradition. This means spreading barley across a stone or concrete floor, creating a ‘bed’ several inches deep. The bed is regularly aerated by ‘turning,’ shoveling grain from the base to the surface using a malt shiel (wooden spade), which promotes consistent germination and prevents mould taking hold.
Another vital factor is the ambient temperature. “We’re at Mother Nature’s mercy, as warm weather can set the germination off too quickly and it could take five days instead of the usual six, which upsets the production schedule, so if it’s warm we also open doors and windows to help cool the floor,” says Graham Manson, Highland Park’s distillery manager.
Commercial maltings can use vessels for germination, and so control the environment rather than being subjected to it. One option is drum maltings, resembling vast tumble driers that blow air at selected temperatures through the grain, which is ‘turned’ by rotating drums. Alternatively, long, concrete saladin boxes have a perforated floor through which air at selected temperatures is blown, with a computer-controlled mechanical ‘turner.’
Time frames for germination are similar whichever option is used, but capacities vary dramatically. A drum takes around 30 tonnes, a saladin box 50 to 150 tonnes, while floor maltings can handle up to several tons.
Kilning and peating at a distillery means manually spreading barley across a perforated floor above a kiln. Heat and smoke rise through the perforations, with kilning taking three to four days.
Again, weather conditions play an important part.
“Every batch is somewhat variable, an east wind is a killer for us as you don’t get the same air flow through the pagodas (chimneys) and this creates various challenges when operating the kiln.
“You never come to work thinking you’re going to go through the motions, the job demands decisions of you every day,” says John Campbell, Laphroaig’s distillery manager.
Meanwhile, commercial maltings can ‘multi-task’ using a GKV (germination and kiln vessel) which includes a ‘turning’ device and the option of peating. Developed in the 1980s, a GKV can process 400 tonnes in around six days.
Commercial maltings also use heat recovery systems when kilning (distillery maltings don’t), and with energy one of three key expenses alongside labour and barley, it’s a significant advantage.
Commercial maltings typically spend eight days malting barley, while floor maltings require 10 to 11 days.
The resulting quality can be the same, but floor malting is generally more expensive, as commercial maltsters produce much greater volumes using far fewer staff (with virtually no manual handling).
Additionally, floor malted barley can yield two to five per cent less spirit per tonne.
Statistics provide pragmatic comparisons, but floor malting isn’t just about numbers, as this element of tradition of the process is also part of a distillery’s identity, and has an emotional appeal for malt whisky fans and distillery visitors is harder to quantify.
“Floor maltings were part of the original concept and the funding, the cost of a new distillery is already high and adding maltings makes it even more expensive, but if you’re looking to achieve a point of difference you can’t cut corners,” says Anthony Wills, managing director, Kilchoman.