During steeping, the barley kernels are soaked in water, and they absorb water until the water content reaches approx. 42-48%. When the water content reaches this level, the germ will start producing a hormone called gibberellic acid. Gibberellic acid is the initiator of germination in the grain. The hormone is transported to the aleurone cells, where it starts the formation of a number of enzymes.
MALTING
Malting is thus an expression of the controlled germination of barley kernels that takes place on the malt floor in Ærø Whisky's brewery. After casting, the barley kernels are allowed to germinate further until we see the germ start to stick out from the barley kernel. Ærø Whisky malts approx. 600 kg. at a time under uniform conditions. The kernels are turned continuously so that they can germinate separately. If the roots are not turned, they run the risk of getting entangled in each other, and thus being very difficult to separate. As a natural part of the germination process, the aleurone layer and the germ form enzymes capable of breaking down the nutrient reserves (starch and protein) stored in the seed white.
The starch grains are surrounded by a protein matrix, which must be broken down by proteases. Proteases are enzymes that break down proteins by cleaving their peptide bonds. These are formed in the aleurone and scutellum layers before the starch-degrading enzymes can access the starch. In addition, the seed white contains, among other things, β-glucans, which are structural components of the cell wall in the seed white.
Two important starch-degrading enzymes are active during malting, namely α-amylase and β-amylase. The α-amylase is formed during germination in the aleurone layer; The α-amylase, on the other hand, is an inactive enzyme in the seed white of the barley kernel, but it is activated during germination. The two enzymes have different functions, as α-amylase cuts the long starch molecules into smaller pieces of varying length, whereas β-amylase releases two connected glucose molecules from each of the long starch molecules. The difference is because α-amylase is an endoamylase and hydrolyzes α-1,4 bonds inside the starch molecule, while β-amylase is an exoamylase that hydrolyzes α-1,4 bonds from the non-reducing end of the starch molecule to release malt sugar (also called maltose).
In addition to α-amylase and β-amylase, β-glucanases are also formed, so that the β-glucans in the cell walls of the seed white can be broken down. When the cell walls are broken down, this means that the amylases have easier access to the starch grains. In addition to giving the amylase easier access to the starch, it is very important that a large part of the β-glucans in the seed white is removed before the beer wort has to be filtered, as too high amounts of β-glucans cause slow filtration. When β-glucans dissolve in water, a very viscous (thick) solution is formed, which can clog the filter.
The production of the malt is an imitation of the germination that takes place in barley kernels when they are sown in the field in the spring. When the barley kernels in the soil absorb water due to the soil's moisture, the germ will form the hormone gibberellin, which initiates the germination process. α-amylase is formed in the aleurone layer and the β-amylases are activated, so that the starch in the seed white is broken down – and proteases form amino acids and small peptides. The germ uses the energy contained in the broken down starch and protein to germinate. When the first green leaf sees the surface of the earth, energy from the broken down starch and protein is no longer needed, as the plant can now carry out photosynthesis. The egg white can thus be thought of as the barley kernel's "food package" and used as energy when spring comes.
It is important that at the malthouse you stop germination after five days, otherwise the starch will be used to form sprouts and roots, which is not smart when you are interested in brewing as much herb for Whisky as possible.
DRYING
After germination, the kernels are dried with heat from the underfloor heating in the malt floor, as well as hot air from heat guns (also called kiln drying). We carry out this process completely manually, just like in the old days. The difference is that Ærø Whisky does not use an open fire for this process, but, as I said, heat from electricity. Originally, the drying was done over a peat fire, which contributed to the smoky Whisky taste. We use a large oak spade and turn the core approx. 6-8 times a day. The process of turning the kernels is important to avoid mold formation, as well as to ensure uniform drying and avoid the roots/sprouts getting tangled in each other.
The fully dried malt is then squared or ground. Each barley kernel is thus ground to approx. 2-3 smaller pieces. It is important in this process that the malt is not ground too finely. In Ærø Whisky, our kettle is 750 litres. We use approx. 200 kg of barley malt and 650 liters of water for the mashing process.
Barley kernels can contain more than 65% starch. During mashing, the starch breaks down into carbohydrates that can be fermented. In order to give the various starch-degrading enzymes optimal conditions for breaking down the starch, the mashing takes place at different temperatures over 4 stages. Each stage has varying lengths, and the breaks between each stage also have varying lengths.
A typical mash in Ærø Whisky consists of the following steps:
- The water is heated to 50°C and malt is added. The mash then 'boils' (approx. 40 min. rest)
- Heating for approx. 64°C to allow β-glucanases, β-amylases and proteases to work (45 minutes rest)
- further heating to 72° C to allow the α-amylases to work (approx. 15 min rest)
- finally mash at 78° C to break down the last part of the starch in the solution. (approx. 2 min. rest)
In order for the enzymatic breakdown of the starch to really start, it is necessary to increase the temperature to over 60° C to gelatinize (pre-glue) the starch.
The result of the mashing is a complex solution with a lot of maltose, maltotriose, a little glucose and non-fermentable sugars, which are also called dextrins. The solution consists of approx. 75% fermentable carbohydrate, and is now called 'the herb'. It is a slightly brownish cloudy liquid which is very sweet.
When the wort has been obtained through the mashing process, it is pumped into our sieve vessel, which separates liquid from broken malt barley kernels, which we call the 'mash'. This is reused in Ærø Whisky for animal feed. We simply drive the 'mash' on a trailer back to the farm, where there are now 'Friday sweets' for the animals (and they REALLY appreciate that...)
After cooling and oxygenating the wort, it is then pumped into fermentation tanks. When the wort is ready for fermentation, the temperature is thus reduced from the approx. 78 degrees to approx. 23-25 degrees.
FERMENTATION
The fermentation process typically lasts 3-4 days and takes place in large 750 liter fermentation tanks. In the tanks, the yeast cells do not have access to oxygen, as the process must take place anaerobically. In the beginning, however, the herb must contain oxygen so that the yeast cells can make sterols and fatty acids.
During fermentation, the yeast cells will develop heat as a natural part of the metabolic processes that take place. We typically see the temperature rise to around 40 degrees.
As previously mentioned, the wort contains, among other things, glucose, maltose and maltotriose. The sugars found in the herb are broken down in a very specific order, as the yeast must hydrolyse di- and trisaccharides before they can be broken down in glycolysis. Therefore, glucose is absorbed and broken down before maltose and maltotriose. This is due, among other things, to a mechanism called glucose repression, which ensures that the yeast cell does not waste unnecessary energy on breaking down larger molecules when glucose is already present.
The sugars in the wort are divided into two categories depending on when they are broken down during fermentation:
- Main fermentation: glucose and maltose
- Secondary fermentation: maltotriose
Glucose is broken down to pyruvate through glycolysis. Glucose is taken up by the yeast cell by a non-energy-demanding process that is carried out by specific glucose transporters. Glucose is then phosphorylated by the first enzyme in glycolysis, hexokinase. Glycolysis is a term for a series of reactions that take place in the cytoplasm and which result in the formation of two pyruvate molecules. You can call it a splitting of the glucose molecule, since glucose contains six carbon atoms, while pyruvate only contains three.
Breakdown of maltose and maltotriose requires that the sugars are taken up with the help of some specific transport proteins. Once maltose and maltotriose have been absorbed, they are hydrolyzed by intracellular α-glucosidases (among others maltase) to glucose (remember that maltose consists of two glucose units linked together by an α-glycosidic bond). This glucose is then included in glycolysis, just like the glucose that is simply taken up. Sugar molecules consisting of more than three hexose units cannot be broken down by the yeast cells. These sugars are called non-fermentable carbohydrates. This is because the yeast Ærø Whisky uses does not have the enzymes to break down the dextrins (for example α-amylase). These sugars will therefore also be present in the final herb. The yeast cells also need nitrogen to grow; they get this from amino acids that have emerged from the breakdown of proteins during mashing. During fermentation, it is very important to monitor how active the yeast cells are. The type of yeast Ærø Whisky uses is an organic yeast (Edinburgh & California) and a USW-6 rarely reaches more than 8-10% alcohol before growth and fermentation stops. However, growth does not stop because of the alcohol concentration, but solely because the nutrient source is used up.
The taste and aroma of the whisky wort is very complex, and it originates not only from the malt, but also from some of the by-products the yeast produces during fermentation and maturation. The most important by-products in terms of quantity are alcohol and carbon dioxide. In addition to small amounts of glycerol and acetaldehyde, traces of a number of organic acids are also formed, including acetic acid, succinic acid and lactic acid. A number of alcohols are also formed, for example isoamyl alcohol and α-amyl alcohol, which originate from the conversion of amino acids by the yeast cells. Although the concentration of many of these compounds is very small, they have a large impact on the finished herb, as they have a very strong flavor. During the main fermentation, for example, tasty esters are formed, including ethyl acetate.
The yeast is removed after the main fermentation. The liquid organic yeast types can be used for new fermentations, and it is usually reused 5-10 times before being discarded. When the fermentation is finished, the yeast cells settle when we use a bottom yeast. The yeast cells can thus be harvested for use in a new fermentation by pumping them out of the bottom of the yeast tank. When using a water-soluble dry yeast, this is not reused, but is rinsed out of the tank.
After the main fermentation, the wort is a cloudy and very sweet liquid that is now ready for distillation.
DISTILLATION
Distillation is a method of separating liquids with different boiling points. The separation takes place by heating the mixture in a container until one of the substances evaporates. The steam is cooled to condense and the condensate is collected in a separate container.
The distillation method itself has not changed significantly after several centuries. When distilling whisky, it is important that the master distiller ensures that the flavor from the malted barley and the herb is preserved. You could say that the more contact the alcohol has with its kettle, the more flavor it will acquire. The copper from which the kettle is constructed acts as a catalyst for a large number of the chemical reactions that take place during the distillation itself. The kettle releases both flavor and removes unwanted flavors such as sulphur.
The distillation plant at Ærø Whisky is a hand-built German plant from Müller in Oberkirch. The plant is a double distillery in a closed circuit. The process begins with the 'wort' being pumped from the fermentation tank into the first part of the still. This part is a so-called 'pot-still', which most people will probably recognize. A pot-still, although they can look very different, has a large cooking pot at the bottom, and a distinctive 'bulb' at the top, which opens into a swan's neck. In this part of the process, we capture all the aromatic substances in the herb. You can simplistically say that the distillate produced with a pot-still is not a pure product, which is why the flavors are preserved. The herb will now be distilled to approx. 30-35% alcohol and is sent on through a closed circuit to the second part of the process – the column distillation apparatus.
In the column part begins what is called continuous distillation, for which Aeneas Coffey obtained a patent in 1830.
Quite impractical, the herb received from our pot-still is directed to the bottom of the column. Inside the column there are 5 copper plates through which the hot alcohol vapors must pass. At the bottom, the temperature will be 100-110 degrees, but only 80 degrees at the top. This, along with the layers up through the column's 5 copper plates mean that only the alcohol vapors leave the column. The many layers in the column cause the vapors to condense and have to evaporate again to get to the next layer. The advantage of a column still is that you can achieve a very high percentage of alcohol (i Ærø Whisky average 88%), giving a much cleaner product.
The result of any distillation is divided into three separate parts: the head, the heart and the tail. The best and desired portion of the distillation is obtained from the heart.
The transition between the three parts of the distillate is up to the distiller to decide. The art lies in knowing when to start collecting the heart and when to stop again. Ærø Whisky's experienced distillers use their senses to determine where the transitions are. We are of course also helped by a knowledge of temperatures.
The head, or process, can be both tasted and smelled. It usually has a very sharp taste and is foul-smelling as it contains a combination of acetone, methyl alcohol, methanol and ethyl acetate. This part of the distillate is very toxic and is always thrown away. In a batch of 650 liters of herb, it is approx. 4 liters that are thus disposed of. The course starts at approx. 78 degrees, and runs up to approx. 80 degrees
The heart of the distillation (the ethanol) is always completely transparent and almost odorless. In a batch of 650 litres, it is approx. 30-35 liters which can be poured into oak barrels, and thus become Whisky. The heart starts at approx. at 80 degrees and runs until the temperature reaches the point where the 'heart' no longer tastes good. Already at 82 degrees, alcohols are released in the distillate, not all of which are good for the taste. Therefore, the master distiller tastes the condensate, and then decides when we should not 'harvest' more ethanol (Hjerte).
The tail contains a large amount of higher boiling alcohol compounds. These compounds can ruin the taste of the alcohol if you collect for too long. The transition point to the tail can be identified by the taste, smell and milky cloudiness of the distillate. The tail is stored in a 'low wine' vessel, and included in the next distillation, as it still contains some ethanol. The tail starts in Ærø whisky, as before written, as soon as the 'heart' no longer has a satisfactory taste, and runs until we can see the alcohol volume drop to approx. 35% after which the process is stopped.
Some would argue that the positive effect that barrel aging has on whisky, was discovered by market traders and nobles who bought large quantities of the spirit at a time and stored it in various wooden casks over the years. Here it was discovered that the spirit only got better with time, and this led to increased popularity for whisky.
A sea of different types of barrels have been used over time to store whisky and other forms of alcohol. The vast majority of them are still used today, although some are more different. In Ærø Whisky we have mainly used Spanish sherry casks over the years, but have also experimented with both French red wine casks, new American oak and Hungarian oak. The most unique thing we have tried is the use of local Ærø oak, which has added wood to our most unique whisky: Local Oak
SPANISH SHERRY CASKS
Many whisky producers are incredibly enthusiastic about the powerfully sweet Andalusian mulled wine; Sherry. There are many different types of Sherry, each with their own characteristics and nuances of taste. They are all used in whiskey production, although some significantly more than others.
FINO
- A dry mulled wine, with a light yellow color.
- Shades of yeast, bread, herbs, almonds and apples
MANZILLA
- A dry mulled wine with a very bright light colour.
- Shades of chamomile, green apples, lemon, olive and maritime notes
AMONTILLADO
- A dry mulled wine with a semi-light amber colour
- Shades of hazelnuts, fudge, dried fruit and bread.
PALO CORTADO
- A dry mulled wine with a nice chestnut colour.
- Shades of orange, walnuts, tobacco and chocolate.
OLOROSO
- A dry mulled wine with a deep amber color.
- Shades of coffee, leather, tobacco, dark fruit, truffle, marzipan and roasted nuts.
CREAM SHERRY
- A soft and sweet mulled wine with a dark amber colour.
- The nuances are very similar to a sweetened Olorosso.
PEDRO XIMENEZ (PX)
- A sweet and incredibly dark-colored mulled wine.
- Shades of stone fruit, honey, plums, blackcurrants and sweet licorice.
MUSCATEL
- A sweet and a (typically) medium-light mulled wine. There are also dark variants.
- Shades of stone fruit, honey, citrus fruit, vanilla and caramel.
Sherry transfers its flavor to whiskey incredibly well, which is why it is used very often. In addition to the Spanish sherry casks, casks are also used that have contained port wine, red wine, Cognac, Sauternes and, of course, American whisky/bourbon. fruitiness and sweetness
FRENCH CASKS
When you move up the world map from Spain/Portugal to France, we find some casks which often give more spicy nuances than Sherry/port wine.
COGNAC CASK
- Nuances of vanilla, toast, chocolate, cedar, cinnamon and nutmeg.
RED WINE (BORDEAUX & BOURGOGNE) BARRELS
- Shades of strawberry, raspberry, cherry, coffee, pepper, herbs and licorice.
Sauter's dishes
- Shades of apricot, citrus fruits, honey, pineapple, white pepper and flowers.
AMERICAN CASKS
Over on the other side of the Atlantic, particularly suitable casks for whiskey storage are also produced. Scotland probably imports as large a quantity of casks from here as they do from Spain.
BOURBON CASK
- Shades of vanilla, caramel, coffee, nutmeg, mild smoke and bananas.
VIRGIN OAK (FRESH UNUSED OAK) BARREL
- Shades of vanilla, lemon, ginger, pepper and honey.
JAPANESE CASKS
In the old days, Japanese whiskey production used American and Spanish casks, but today an astonishingly high number of Japanese distilleries have their own coopers. The coopers use Japan's own oak; Quercus mongolicus to make these dishes. These dishes have been given the name: Mizunara dishes.
MIZUNARA CASKS
- Shades of fruit, incense, cinnamon and coconut.
ROASTING OF CASKS
Common to all dishes is the roasting. To clean a dish, as well as to add a layer of nuances, roasting is used. Most casks are toasted before being filled with raw alcohol. The degree of roasting is divided into 4 levels, where level 1 is a very mild roast and level 4 is an incredibly hard roast. When roasted at level 4, the wood takes on a furrowed alligator-like structure, and emits some fantastically exciting smoky and spicy nuances. Roasting at level 4 is popular with Bourbon in particular Whisky. The Ærø Whsiky we primarily use a +1 roast. Barrel aging is one of the most essential things when discussing whiskyproduction. An interesting cask aging can make a 5 year old whisky quite engrossing, where an inactive barrel can make a 20 year old whisky bland. Music arises when good cask aging, good craftsmanship, time and passion meet.
