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Why is Grain Selection so Important?

The fundamental defining characteristic of different types of whisky is the mash bill, or the base grain used for the spirit. While there are many other complexities to whisky production that change its flavour, such as cask selection, using peat or blending, there are very distinct flavour profiles associated with certain grains.

It is so important, in fact, that even 5% of a different grain used in a malt whisky means it cannot be classified as such. Read about the differences between malt and grain whisky. On the other hand, the rules for most grain whisky far are more lenient. They can be made from a wide variety of base grains, in flexible proportions.

The makeup of the grain influences the amount of flavour compounds present in the final liquid. Starch, lipid, protein and sugar ratios vary between grains, resulting in different amounts and types of flavour compounds present after fermentation. Ethanol, higher alcohols (fusel oils), esters, ketones, carboxylic acids, sulphur components and phenols can all make it through the distillation process.

Exploring Grain Whisky Flavour

There are four main grains used in whisky production. Malt whisky used malted barley (barley that has been soaked, germinated and dried). American whiskey, such as Bourbon uses mostly corn. Meanwhile, wheat and rye are common additions in grain whiskies for their rich and balancing properties.

Barley: The Backbone of Malt Whisky

Universally adored, malt whiskies are almost synonymous with the category. They usually offer a smooth, rich and complex profile that reflects nuances in production. Heavy in fusel oils, esters, phenols and aldehydes, malted barley builds a full-bodied, complex palate.

Malted barley is the only permitted grain for malt whiskies. The germination process makes sugars more readily available for fermentation, and enzymatic reactions begin to soften harshness. Secondly, kilning or drying with peat fires introduces caramel flavours (via the Maillard reaction) or peat smoke. Explore the flavours of malt whisky below:

• Malt & Cereal: Malted Milk biscuits, Almonds, Hazelnuts, Toast
• Fruity: Apple, Pear, Bananas, Pineapple, Peach, Plum, Citrus
• Floral & Herbaceous: Heather, Honeysuckle, Elderflower, Grass, Thyme, Eucalyptus
• Dessert & Spice: Flavours of vanilla, Honey, Caramel, Ginger, Black Pepper, Cinnamon, Clove
• Smoke (peated whiskies only)

Other Grains: Corn Wheat & Rye

Bourbon is the most predominant grain whisky, which must contain at least 51% corn (it must make up the majority of the mash bill). Corn has a higher sugar content and a lower protein and lipid make-up – creating a light and sweet flavour profile with fewer rich fusel oils than malt whisky. Low protein content means less sulphur, which can result in a smoother, approachable taste. Bourbon is usually distilled to a higher proof, which leaves behind more of those rougher flavour compounds.

Rye offers more spice elements such as guaiacol (peppery and clove-like). Fermentation yields buttery and coconut-like notes owing to prevalent lactones. Finally, beta glucans increase the viscosity of the wash, which contributes to a full-bodied mouthfeel.

Finally, wheat can produce a mild and delicate spirit with minimal fusel oils and phenols with higher levels of floral esters.

Corn	Rye	Wheat
Dessert: Honey, Maple, Toffee, Butter, Toasted almonds Fruit: Apple, Pear, Cherry, Red Fruit, Banana, Coconut Floral: Elderflower, Spice: Cinnamon, Clove, Black pepper	Spice: Black pepper, clove, cinnamon, Nutmeg, Anise, Liquorice, Ginger. Herbs: Dill, Thyme, Eucalyptus, Mint Fruit: Apple, Pear, Cherry, Plum, Citrus Zest Baking: Walnuts, Hazelnuts, Cocoa	Pastry: Honey, Caramel, Shortbread, Milkbread, Vanilla, Cocoa, Almonds Fruit & Floral: Apple, Pear, Apricot, Peach, Coconut, Elderflower, Chamomile, Jasmine, Orange blossom Spice: Cinnamon, Nutmeg, White Pepper

How do Mash Bills Impact Whisky Flavour?

Mixed grain mash bills are an excellent way to balance flavour profiles; for example, adding a small amount of rye introduces more savoury and spicy flavours. Meanwhile, wheat whisky may be able to mellow out sharpness and maize can sweeten the deal.

However, there are some rules. Rye whisky must use at least 51% rye as the base grain, meanwhile, Bourbon must use 51% corn.

What Gives Whiskey Its Flavour?

There are four main ways that a whisky gets its distinct flavour these are grain selection, peat, fermentation and cask selection.

• Grain Selection (mash bills): The chemical makeup of different grains results in a unique flavour profile
• Peat: Peat fires are a traditional way of drying malted barley (especially in Scotland), and they introduce unmistakable smoky flavours.
• Fermentation: the type of yeast used, the fermentation rate and the period of fermentation determine the amount of flavour compounds present in the wash.
• Cask Selection : Whether it's sherry, Bourbon or STR or European or American oak, the type of barrel used for maturation will have a distinct influence on the final profile.

There are nuances in every stage, but generally, distilleries can create a completely unique spirit by tinkering with the above factors.

The Impact of Grain Choice on Whisky Production

The composition of different grains is evident all the way through production, from fermentation to maturation.

• Fermentation: Yeast metabolises grain nutrients; with different ratios, come different metabolites (by-products) – changing the overall flavour profile.
• Distillation: Copper pot batch distillation captures a broad range of flavour compounds; meanwhile, column distillation (common in Irish whiskey) produces cleaner spirit with a higher ABV and fewer aromatics. Different grains create diverse flavour profiles which each distillery can fine-tune.
• Maturation: Depending on the makeup of the heart cut, ageing in oak can accentuate the flavours, soften or balance them.

Frequently Asked Questions

How does the choice of grain impact the price of whisky?

The price of most base grains is approximately similar. However, malted barley comes with the added stage of germinating and drying, which can make it more expensive. Usually, the price reflects the quality of the liquid and brand prestige.

Can you taste the difference between whiskies made from different grains?

Yes, there are usually distinct differences between whiskies made from different grains, although most grain whiskies use mixed mash bills, making their differences more subtle. Secondly, production decisions can significantly influence the flavour profile, making grain nuances harder to detect.

Are there any whiskies that use a blend of grains?

Single malt whisky and single grain whiskies must be made from 100% malted barley or 100% of the named grain, respectively. All other grain whiskies use a blend of grains.

What are the requirements for single grain whisky?

Single grain whisky must contain 100% of the chosen grain in the mash bill and no others. Most single grain whiskies are still aged in oak, for a minimum of three years and one day.

How do ageing requirements differ for single grain and single malt whiskies?

Most whiskies have a minimum ageing requirement of three years and one day. The main outlier is the grain whisky - Bourbon – which requires only 2 years in virgin American oak. Grain Scotch whisky or single malt Scotch regulations outline very specific ageing requirements.

Which grain is Bourbon whiskey made primarily from?

Bourbon is primarily made from corn (maize) – it must make up at least 51% of the mash bill.

What to read next

What is single malt whisky?

How does production change whisky flavour?

Your guide to vanilla and caramel whiskies

Your guide to warm and spicy whisky