Malted Grain Makes Many Whiskies Tick

The odds are good that your favorite drink relies on the amazing power of malted grain. Scottish single malts are made entirely with malted barley, while most bourbons use a portion of malted grain to contribute the enzymes that convert the starches in corn into fermentable sugar. We even owe malt a debt every time we savor a roasty porter or sweet, hoppy IPA.

For such an important part of whiskey, malting remains mysterious to many. But at its core, it’s not a complex concept. In essence, malted grain is sprouted grain that’s dried and toasted at just the right moment. The germination process begins to turn the starches inside the grain into accessible sugars that yeast will later transform into alcohol.

There are a few different strategies for malting. Traditional Scottish distilleries used floor malting, a labor-intensive process that calls for spreading grain into a thin bed across the floor of the malt house, then turning it every few hours by hand with large, flat-bladed shovels to prevent mildew and avoid tangling the tiny rootlets that emerge from each grain. After a few days, the malt would be kilned, and in the parts of Scotland that lacked trees for lumber, peat cut from nearby bogs would be used.

Corsair malts much of their own grain at their own malthouse. Image via Corsair

Today, floor malting is used at just a handful of distilleries, and most malt is made in industrial factories using computer-controlled equipment. Box malting is the most common method, which uses a climate-controlled box to keep grain at exactly the right temperature and moisture level for germination. Then, they use an electric kiln to stop germination and toast the grain. Because their systems are computer-controlled, big malters need barley varieties that behave very predictably, germinating consistently to the same amount within the same number of days.

As craft distilling has grown, craft maltsters are now making an entrance. These new malteries might use a combination of box-malting and floor-malting techniques, and many make malt with different barley varieties than the big guys. But no matter how it’s made, malt is the key that starts the engine of fermentation.