Mix and mash

Mix and mash

Ian Wisniewski asks what the term ‘mashbill' means, and what significance this has for bourbon

Production | 23 Jul 2010 | Issue 89 | By Ian Wisniewski

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The mashbill is a ‘recipe’ of grains from which bourbon is distilled. Traditionally this comprised corn, rye and malted barley, with the vast majority of bourbons continuing to use these three grains. However, a minority of brands have a mashbill that includes wheat (in place of rye) together with corn and malted barley. Referred to as ‘wheated’ bourbons, these include Maker’s Mark and Old Fitzgerald.

“The mashbill is the foundation of building your flavour;” says Chris Morris, master distiller Brown-Forman Woodford Reserve.

The mashbill must include a minimum of 51 per cent corn, with the balance accounted for by ‘cereal grains,’ which gives distillers a certain freedom of choice. There is no upper limit on the level of corn used, though it typically accounts for up to 80 per cent of the mashbill.

A particular variety of corn, No 2 Yellow Dent, is the usual choice as this is considered to give the best flavour and yield of alcohol compared to other varieties. Corn is primarily sourced either locally in Kentucky or from North Dakota, with South Dakota and Indiana secondary sources.

Although corn accounts for the majority of every mashbill, it’s influence on flavour tends to peak in the freshly distilled spirit, and become less noticeable in mature bourbon.

“Corn is what makes the spirit taste the way that it does, with a corn and sweet grain taste really coming through in the new whiskey off the still. The other grains don’t show up as much in the spirit as the corn does, but that changes when the aging process begins, and within the first year of aging the character of the rye or wheat starts to come through,” says Parker Beam, master distiller, Heaven Hill Distilleries.

This explains why corn is often described as ‘neutral’ in terms of the flavour it contributes to mature bourbon. Even when corn gets the credit for providing mature bourbon with, for example, some butteryness, this is essentially
an underlying rather than a primary characteristic.

“The soft corn note which is deep in its character, evolves with the caramel and vanilla notes which come from the barrel to develop some nutty notes, and so corn contributes to other flavours rather than a noticeable corn flavour,” says Morris.

Similarly, malted barley only gets the credit for providing underlying biscuity, malty and chocolate notes, together with some dryness. Such a low key contribution is hardly surprising, considering that malted barley generally accounts for a mere 10 to 15 per cent of the mashbill. But then barley, which is cultivated in North and South Dakota, and malted in Milwaukee, is essentially prized for the enzymes it contains, rather than for any flavour contribution.The enzymes play a key role once the grain has been milled (crushed) and is cooked in hot water. This is when the enzymes convert the starches contained within the grains into sugars. The resulting sugary liquid is subsequently fermented by adding yeast, converting the sugars into alcohol, and providing an alcoholic liquid of around eight to 10% ABV, which can be distilled into spirit. Consequently, corn is often regarded as the ‘engine’ that essentially provides alcohol rather than flavour, and malted barley is perceived as the ‘workhorse’ that delivers enzymes. This means that rye and wheat are the two grains that can contribute most significantly to the flavour of mature bourbon.

“The higher the rye content, then generally the more spice, complexity and dryness in the resulting bourbon,” says Harlen Wheatley, master distiller at Buffalo Trace distillery.

Rye contributes a range of spice notes, including nutmeg, clove and cinnamon, which can also be intensified by the aging process. Bourbon must be aged in oak barrels which have been charred on the inside by applying a flame, with the heat ‘releasing’ various flavour compounds including vanillin and spice notes which are ‘bound up’ in the oak. During the aging process the maturing spirit extracts vanillin and spice notes from the oak.

“Some clove and cinnamon notes also come from the barrel, so the spice notes from the rye become emboldened and boosted by the barrel,” says Morris.

Using wheat, which is mainly sourced from North Dakota, may be limited to a minority of brands, but it’s also traditional. Records show wheat has been included in the mashbill at bourbon distilleries since the mid-19th century. Wheat makes a significantly different contribution compared to rye, but this is essentially down to the different ways that wheat and rye interact with the influence of the oak during aging.

”Wheat results in sweeter tasting bourbon, but not because the wheat is a sweeter grain. Wheat is not as rich as rye so it allows more of the vanilla sweetness from the oak to show through, compared to rye which masks some of those sweet flavours,” says Jim Rutledge, master distiller at Four Roses distillery. Needless to say, which is preferable depends on the style of bourbon that each distiller wishes to make. Another option is a mashbill comprising four grains rather than the usual three, such as Woodford Reserve Masters, a limited edition released in 2005.

“We altered the proportions of corn and rye to add wheat, alongside malted barley. In the regular Woodford Reserve there’s a very subtle hint of nuttyness, but what really came out in the four grain was the development of a lot of nutty character, including pecan and walnuts, which leads the palate. This nutty character is down to the interaction of wheat with the other grains,” says Morris.

So, the mashbill undoubtedly influences a bourbon’s flavour profile, but to what extent?

“The mashbill accounts for around 20 per cent of final flavour, with the fermentation process, type of yeast accounting for around 10 per cent. The distillation regime is another 20 per cent, with the aging process at around 50 per cent,” says Wheatley.
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