For the past 20 years the rye whiskey market in the US has been undergoing a revival. What was once an almost forgotten category has become big business and, according to research by Accio, the US rye market is set to increase from $1.2bn in 2024 to $2.5bn by 2033.

Michter’s, the reigning World’s Most Admired Whiskey, is one of the leading American rye producers with its flagship Kentucky Straight Rye, a 10 and 25 Year Old, Barrel Strength Rye and Toasted Barrel Finish Rye. To understand what sets the brand apart, Drinks International caught up with Andrea Wilson, the brand’s master of maturation to discuss the relationship between rye and wood.

Can you explain how wood treatment affects ageing rye whiskey?
With rye we take a long-form approach. We begin by asking ourselves what we want the end whiskey to taste like before we start applying our maturation process.

We want to bring out some of the confectionery notes to balance the natural spice that comes with working with a rye whiskey. And to achieve this we have to define the seasoning process and the toast and the char.

For Michter’s we naturally season and air dry all of our wood for at least 18 months and sometimes up to five years. It’s not just physically drying the wood, it's also chemically and microbiologically changing the wood and that’s very important because we want to get rid of chemistry that we don’t want – things that can be grassy or vinegar like, which don't really contribute to the flavour profiles we’re looking for.

But we also want to enhance some of the characters we are looking for, such as vanilla or a gentle smokiness. The seasoning process is critical as a basis, and then we want to get into the toast and the char. There are hundreds of different toasting profiles based on temperature and time, and depending on which you choose, you can really enhance those desired characters.

Then using a lighter char will further accentuate the flavour, particularly the fruit esters and spice. But you can’t do one thing without the other. You have to think about the whole process and how it’s all going to work together to achieve what you want.

Do you rotate barrels during maturation?
When you put a barrel into a warehouse there are many variables, such as the number of floors, the airflow, the humidity and does it have a dirt floor or a concrete floor? They seem like simple things, but they can have a dramatic impact on how that whiskey is going to age.

We operate a more controlled environment by reducing the number of different variables there might be. During the winter here, we experience cold and dry months and, as a result, we actually heat up our warehouses and we heat to a certain liquid temperature. We’ll then turn off the heat and allow the whiskey to cool down. By doing that we’re simulating the natural seasonal change that we would normally call a cycle. When whiskey gets warm it’s a volatile substance, so the pressure builds and the whiskey pushes into the capillaries of the wood. When it cools down, it flows back the other way to the centre of the cask, pulling colour and flavour and all the richness you want. So that additional interaction with the wood and the winter months when we normally wouldn't have as much interaction really helps us increase the maturing quality of that final spirit.

We have a lot of barrel programmes here in the US and I get asked all the time why Michter’s doesn’t run one. But the concept of a barrel programme was about the fact that single barrels can age very differently based on a placement in a warehouse. Higher-floor warehouses can experience accelerated ageing versus the lower floors and people enjoy the opportunity to go in and taste through different barrels. But ours is only four floors high, and we want continuity of ageing from the top of the house to the bottom of the house. I tell people it’s harder to create a consistent, repeatable, single barrel product than it is one that has tons of variation in it. That’s one of the things that we’re really proud of – the consistent repeatable quality we can deliver to our people who decide they love rye.

What would you say is the biggest challenge when producing aged rye?
I think the beauty of rye is that at different points in its lifecycle it can showcase itself differently. We’re known for producing beautiful rye whiskeys and also extremely aged ryes that are not too oaky. We want to preserve those beautiful characteristics that you know as rye.

But there’s a point of diminishing return for heat cycling. You don’t want to keep doing it because you don’t want to keep losing liquid from the barrel through the angels’ share, but at the same time you don’t want to take on too much of the tannic characteristics, too much of the characters of the wood that just overpower the beauty of the spice and the confectionery notes.

What do you see for the future of rye?
You know, we’re playing the long-term game. We establish a forecast, we plan against that forecast, and we don’t make decisions differently just because we can. During Covid-19, everybody wanted more whiskey and brands were stretching themselves, but we weren’t going to sacrifice our principles just so we can sell more.

Rye was actually our flagship for a long time and then the bourbon craze happened, so we’re about 50-50 today. More recently, bartenders have been using rye, which has really continued to support and bolster the rye category. Matt (Magliocco, Michter’s executive vice president) is right when he says that we can’t keep rye in stock. I mean, it just sells straight away, but I think that’s a testament to us and also the wider rye category and I can’t see it slowing anytime soon.