Master Distiller Blog No.03 — The Truth About Malting
David Hsieh
Why the grain must germinate before it can become whisky, and whether floor malting really does make a difference in the glass — a distiller’s view of the process
By David Hsieh — Master Distiller, Tankyu Distillery | Presenter, Business Whisky Guide Podcast
Adapted from Business Whisky Guide Podcast EP3 — ‘Sprouted’, recorded in Scotland, February 2023.
The raw material of whisky is barley. What arrives at the distillery, however, is not barley as it comes off the field but barley that has been through malting.
Why malting is necessary at all
You cannot, in practice, simply take barley as it is — and the reasons have to do with what is locked away inside the grain.
The first is the matter of enzymes. The starch inside raw barley cannot be fermented directly into alcohol; it must first be converted into fermentable sugar. The agents of that conversion are the diastatic enzymes the grain itself releases as it begins to germinate. Malting is, in this sense, a deliberate waking-up of those enzymes.
The second reason is less often mentioned but no less important. Germination also activates a second set of enzymes — proteolytic enzymes — which set to work on the cell walls of the grain. The hard, glass-like barley kernel becomes friable, crumbly, and can then be milled to the kind of grist that mashing requires. Without that structural change, milling and mashing both fail at the first hurdle.
Steeping and germination: the balancing act between water, temperature and air
Once harvested, barley is held at about 12 per cent moisture for long-term storage; to enter germination, that moisture has to be lifted to roughly 45 to 46 per cent. The process by which this is done is called steeping.
The earliest practice was to drop sacks of barley into a river — which gave a germination rate of only about fifty per cent. Barley needs to breathe; submerged without interruption, the grain produces ethanol, lactic acid and carbon dioxide, and effectively suffocates itself. Modern maltings therefore use a cycle of steep, drain, re-steep, with a total duration of roughly 40 to 50 hours, allowing water in by stages and letting the metabolic gases out in between.
Once the grain is into germination proper, the operator is balancing three things at once. Moisture has to be held in the 45 to 46 per cent band — go beyond fifty and the grain drowns. Temperature has to be kept below 20°C — let it run higher and germination becomes uneven and microbial spoilage takes hold. And the bed has to be ventilated; germination is exothermic, and unless the heat is allowed out, local hot spots will form.
From shovel to drum: a hundred years of evolving the kit
The original technique was floor malting — the steeped grain spread across the floor of the malting house in a layer some 15 centimetres thick, and turned every few hours, with shovels, to release heat and to keep the rootlets from matting together. It is work of considerable physical demand, traditionally turned with the body always working from the same side; the resulting shoulder injury is the source of the nickname Monkey Shoulder.
Later, a Frenchman by the name of Galland designed an alternative: a long metal trough fitted with cooling water and forced ventilation, which solved both the heat-dispersal problem and the turning problem in one. His apprentice Saladin took the idea further, mounting a set of mechanical turning arms that travelled along the trough and turned the bed automatically — and so the Saladin design was born.
Engineering then carried the geometry from rectangle to circle: the circular germination vessel, with a central spindle driving turning rakes through the radius of the bed. Further still, the drum maltings — a metal cylinder several metres in diameter, rotating slowly while the grain tumbles inside, the whole assembly fed by ventilation that controls temperature throughout. Today’s large maltings run principally on circular vessels and drums.
Who still does floor malting?
Most Scotch distilleries today buy their malt in from professional maltsters — Bairds, Crisp and Simpsons among them. A small handful, however, still maintain floor maltings of their own: Springbank, Bowmore, Highland Park, Laphroaig and Kilchoman. It is perhaps not a coincidence that these names are also associated chiefly with peated whisky.
Does the method change the flavour?
From a distiller’s point of view, the question deserves a direct answer: between floor malting, the Saladin system and the drum, is the difference detectable in the finished whisky?
In practice, very little. The final quality of the malt is determined principally by barley variety, by moisture profile, by evenness of germination and by the conditions during kilning. The method of turning the bed contributes far less than any of these. Floor malting endures less because it produces a measurably different whisky and more because it carries forward a piece of distilling culture — a respect for a slower, hand-worked rhythm — rather than because of any flavour it imparts.
When a label draws attention to ‘traditional floor malting’, then — it tells you that a traditional method has been carried forward. It does not, in itself, promise that a traditional flavour has been.
About the author
David Hsieh is master distiller at Tankyu Distillery. He has previously worked as a distiller at several whisky distilleries in Scotland. He holds an MSc in Brewing and Distilling from Heriot-Watt University, and is the host and producer of the Business Whisky Guide podcast, Taiwan's #1 whisky podcast.
About the distillery
Tankyu Distillery is one of Japan's few public-private (公設民営) craft distilleries, located in Higashikawa, Hokkaido. Founded in 2020, it produces single malt whisky and craft gin using pristine spring water from the Daisetsuzan mountain range — water so pure that Higashikawa remains the only municipality in Hokkaido without a municipal water supply. Learn more at tankyudistillery.jp.
Source
・ Business Whisky Guide podcast EP3 — ‘Sprouted’, recorded in Scotland, February 2023. Original audio: youtu.be/j_VzIgkJVHc