HUMIDITY ITS ROLE IN YOUR DISTILLERY

HUMIDITYOVERLOOK HUMIDITY AT YOUR OWN PERIL WHILE CASK WAREHOUSE MANAGERS WILL OFTEN TALK ABOUT TEMPERATURE, HUMIDITY CONTROL SHOULD ALSO BE PART OF THEIR CASK AGING AGENDA. VELO MITROVICH REPORTS

During lockdown I have had more opportunities to listen to music and to read books. One of the books I have managed to catch up with was Pete Brown’s latest - Craft: An Argument: Why the term ‘Craft Beer’ is completely undefinable, hopelessly misunderstood and absolutely essential. If you have not read this then I suggest you do as it seeks to answer some important questions. Reading this book made me think, it definitely helped me to begin to crystallise my thoughts on the craft beer movement. You have to feel some pity for Kavalan’s master distiller in Taiwan. The island, off mainland China, is subtropical with high temperatures and humidity, occasional typhoons and a cold winter that lasts about four weeks at best. If ever a whisky environment can be far from Scotland, this is probably it. Angels just don’t want a sip of the award-winning single malt whisky. With loses of up to 15 percent a year, it seems they want to drink the whole cask! No wonder the majority of Kavalan’s whisky is aged seven years or less, with most bottles having NAS on them – No Age Statement. Whisky matures in the cask – not in the bottle – during aging when so much of the flavour comes from the three elements that come out to play: the actual cask, aging time, and essential chemical reactions that take place between all these factors. Almost like the tides going in and out, with the wood used in casks being semi-porous, it expands on hot days and contacts during cooler days or at night. Like as if the casks are alive and

breathing, this action allows for flavours, water and alcohol being exhaled and the aromas and smells of the sounding area being drawn inside. You can taste the sea in some Scottish whiskies aged near the sea; Kavalan says its whisky has a somewhat tropical taste, again from environment. Many of the factors affecting casked whisky seem to be accepted as just part of the process. Too little humidity and your barrel gives up water; too much humidity and you lose alcohol. There have been even a few cases in the Scottish whisky industry where casks that sat for decades had alcohol levels which dipped below 40% ABV, which tragically meant the long-kept whisky could no longer be called Scotch whisky. But humidity is one part of the process that you can take control of and relatively easily. The ability to control levels of humidity is one of the most significantly overlooked issues in modern industrial activity such as distilleries and breweries. Part of the reason for this is, most people don’t notice humidity to anywhere near the same degree that they are aware of other equally basic phenomena, such as heat, cold and draughts. But, as cask expert and writer Matt Strickland says, “Humidity is just as important a consideration though it’s the one that many distillers think about the least.” And it’s just not the obvious reasons why humidity needs to be factored you’re your cask warehouse management. Humidity can have a profound influence on materials, on production costs, on service and maintenance expenditure and on asset durability, as well as energy consumption and the resultant 72 | WINTER 2021 DISTILLERS JOURNAL

environmental impact, says Lindsey Henderson of Humidity Solutions, an acknowledged expert with more than 30-years’ experience in the air quality industry.

According to Henderson, uncontrolled humidity in a distillery causes: u Condensation: The result of the fact that the air, which inevitably contains a certain level of moisture, has a different temperature from the surfaces with which it comes into contact. u Corrosion and rust: The combination of humidity and oxygen makes metals corrode, significantly affecting both strength and durability. Iron and steel rust and lose structural integrity, copper is plagued by verdigris, affecting electronics and electrical equipment. u Clumping and blockages: Powders and granulate absorb humidity particularly easily. They then clump together, affecting quality and causing blockages in processing equipment, as well as providing a fertile breeding ground for bacteria.

CONSISTENCY RULES

One problem that all distilleries have to some degree is achieving a high degree of consistency with product. Every time a customer opens up a bottle of your whisky, rum or other aged spirits, they want it to taste very similar to the last one.

“Seasonal fluctuations in humidity result in inconsistent production conditions. And that can affect product quality, energy consumption, and of course most importantly profit margins,” says Henderson. “Today’s operations strive for consistency and conformity across production over many years. Controlling variables such as humidity must be a concern across all aspects of the production operation.

“A good example of this is how the lack of humidity control in a whiskey distillery was causing large losses due to evaporation. And in that particular application, the whiskey was being matured in oak casks over years to get its unique flavour and colour and these wooden casks they equalised with the surrounding air which means that liquid transforms outwards and then the air humidity in the story to when the air humidity in the storage areas is too low. So, when the air around the casks is too low, the moisture transforms outwards This means a loss of whiskey and of course loss of income.”

Distillers joke – somewhat – about losing part of product to the angel’s share. But it you’re aging whisky for 10, 12 or even 20 years, a two to three percent loss each year starts adding up to a significant amount.

“This ‘angels’ share’ that occurs in the maturing process is now controlled by installing an Adiabatic humidification system which uses a high-pressure pump station and controls several zones independently using nozzles mounted on heads that distribute the moisture in a controlled manner,” says Henderson. “Humidifying to the correct level and stabilizing the humidity in the storage areas have ensured losses are at an absolute minimum and profit margins are no longer affected.

“Similarly, as too little humidity can cause issues, there are also many problems associated with too much humidity as stated above, while we may know of these problems the important thing is how they are dealt with. The layman’s idea about dealing with humidity and condensation problems is simply to turn up the heating, However, turning up the heating has only very limited effects on humidity,” she says.

Heating does not alter the absolute level of humidity present in the air – it only increases the overall temperature. The relationship between the heat content and the water vapour content of air is relatively complicated and non-linear, and temperature isn’t as important as air humidity, because of the dew point. As you might recall, the dew point is the temperature to which air must be cooled to become saturated with water vapour, or in other words, to achieve a relative humidity of 100 percent. At this point the air cannot hold more water in the gas form. The higher the dew point rises, the greater the amount of moisture in the air.

Heating then usually results in excessive energy costs to very little effect, because it takes much more energy to heat moisture-laden air than to heat dry air. Heating, too, does not provide a yearround solution. In virtually all cases, removing moisture from the air using adsorption dehumidification technology is significantly more effective, and makes it possible to work with consistent levels of effectiveness regardless of season or weather.

“Humidity will always try to equalise; it’s always looking for equilibrium,” says Henderson. “When the surrounding area is very dry, then moisture – water – goes out from the casks. When the humidity is very high, nothing will transform out of the casks. It’s a bit like a full sponge. If it’s full of water, it can’t absorb anymore.”

According to whisky sommelier Joel Hauer, for whisky to properly age, it has to breathe, and anytime you store a liquid in a non-airtight container, you are going to lose some of it to evaporation.

Depending on how long the whisky is aged and the environment, as much as half of the cask can be consumed by the angel’s share. “Whiskies increase in price and rarity as they age, and this isn’t just because of the time required to make them. A distillery still has to pay to produce all the whisky that evaporates, and these costs usually find their way into the remaining whisky’s price,” says Hauer. The dilemma is, you want your whisky to age properly and this requires the cask to breath. On the other hand, you don’t want to see your profits sucked up by greedy angels.

According to Henderson, the angel share that occurs in the maturation process can be controlled by installing a humidification system which uses a high-pressure pump station that can control several zones independently, using nozzles mounted on heads that distributes the moisture in a controlled manner. “If you humidify to the correct level and stabilise the humidity in the storage areas, you make sure that your losses are at an absolute minimum,” she says. “It’s not big money to install a humidification system and by maintaining a stable humidity, it can have significant benefits on the production,” says Henderson, adding that a return on investment can be as short as 12 to 18 months.”

COVID 19 AND AIR QUALITY

If you talk with those in the industry and doing an internet search will turn up no reports of a distillery anywhere in the world having an issue with workers getting Covid 19. However, with the meat processing industry it has been completely different. During the initial Covid pandemic, a meat processing plant in Germany was dumbfounded by the number of cases in its work force. The plant followed every government regulation to the ‘T’, at no time was it trying to cut corners when it came to worker safety. What got them really wondering was, it wasn’t as if workers were shaking hands with each other every two seconds. Employees were wiping surfaces, keeping approved distances for each other, washing hands, but still the numbers rose.

They decided then to take a different approach. Due to the expense in keeping the workplace cool, plant air once chilled was recirculated with little exchange. Although the journey of a virus when propelled by a sneeze is short, viruses are experts on hitching rides on slightly

Along with controlling the humidity, it is also every important that you have a good filtration system.” Lindsey Henderson, Humidity Solutions

larger dry particles which increases the distance they can travel. With all the bone cutting, sawing, and general meat processing happening, the air in all processing plants was filled with tiny particles. At this German plant, portable air filters were installed in the workplaces and Covid numbers dropped considerably in a fast period of time.

As life normalises in the UK, distillery visitor centres are being opened for the first time in well over a year. With mask wearing becoming an option, how will you keep visitors safe? “During the summer to ensure a healthy air low, windows were opened to flush out viruses. However, with winter coming that is not a practical approach for visitor centres,” says Henderson.

She says that according to studies she has read, humidified air has a huge number of tiny water droplets. When they collide with a virus, it makes the virus heavy and drop to a surface which can be easily cleaned, sterilised and reducing further transmission. “In looking at getting the humidity to the right level for this to occur, 40 to 60% is your optimum level. This is the level where viruses, bacteria and mites are at their least active level,” says Henderson. “Along with controlling the humidity, it is also every important that you have a good filtration system.”

What happens inside a cask to aging whisky, rum, tequila or other aged spirits can only be considered pure magic. A harsh, almost tasteless, high-alcohol spirit goes into a cask, and three to 30 years later, comes out a refined gentleman, with flavours that almost seem impossible to have got simply from what went in.

It’s the oak, the char, what went first into the cask, and warehouse conditions. While some many cask warehouse managers keep an eye mostly on the temperature gauge, just as important is the humidity.

Humidity control technology is the most cost-effective and environmentally responsible way to tackle many problems widespread throughout the distilling industry. It’s an easy, inexpensive way to implement pro-active measures that help make sure you can maintain the value of your spirits, casks, processes and other high-value assets. As all buildings and locations are different and have their own unique requirements, it is wise to get specialist advice to ensure the most appropriate solution.