Production process

Question 1

Name the 12 stages to processing barley.

Answer 1

1. Harvest
2. Drying
3. Analysis
4. Steeping
5. Germinatin
6. Kilning
7. Storage & Analysis
8. Delivery to distillery
9. Milling
10. Mashing
11. Fermentation
12. Wash

Question 2

Explain steps 1 (harvest) and 2 (drying) to processing barley.

Answer 2

After harvesting the barley has to be dried and stored. Barley grown in the UK is too wet to store directly, so it must be dried first.

Prior to drying, the barley is tested. Automated barley sampler allows the operator to sample the barley in multiple locations from the safety of the control room. The sampler will suck up a number of samples from a lorry and send them to the control room or laboratory where they can be mixed to provide a good sample.

Question 3

When analysing the barley in step 3, what does an expert check for?

Answer 3

1. Moisture: This is checked to ensure the consignment is within the contract specification and to check that it has not been dried at the farm.
2. Nitrogen (for protein content): This is vital as the nitrogen content is inversely related to potential spirit yield, that is the higher the nitrogen level the lower the potential spirit yield from the barley.
3. Screenings (or size of the grains): The barley should be of the same size to ensure even malting.
4. Germination (to see if the barley is alive and will grow): The barley must be able to grow to produce malt.

Only after extensive testing will the barley be puchased for malting. Prior to malting, the barley is often required to be stored for a period, so it must be dried down to a safe storage level.

Question 4

What are the conditions for the safe storage of barley for a number of years prior to use?

Answer 4

• must be dried to under 12% moisture
• kept under 15°C

Question 5

How is barley dried?

Answer 5

Barley can be dried in a number of different ways, but the process is simply blowing warm air through the grain to remove the excess moisture.

Question 6

What does an automated barley sampler do?

Answer 6

It allows the operator to sample the barley in the lorry in multiple locations from the safety of the control room (no need to climb up into the lorry). The sampler will suck up a number of samples and send to the control room or laboratory where they can be mixed to provide a good sample.

Question 7

The malting process is made up of which 3 key stages?

Answer 7

1. Steeping
2. Germination
3. Kilning

Question 8

Describe the structure of a barely grain in its different parts.

Answer 8

1. The microphyle: a small hole through which water can enter the corn. Unless the corn is damaged this is the only route for water to enter the grain.
2. The embryo: the living part of the corn; it is like the baby plant.
3. The endosperm: the starch reserve that will provide the new plant with the resources for initial growth.
4. The husk: the “skin” that surrounds and protects the barley.

Question 9

What occurs during step 4 (steeping) phase of the barley process?

Answer 9

Steeping is the first stage of the malting process. Barley grains are soaked in water and then air-rested for alternating periods to bring up the moisture level and initiate germination (stage 2 of malting).

Barley is typically “dropped” into the steep via a chute. There are temperature probes and overflow drains where dust and debris can be drained from the top of the steep.

Multiple steeping (more than one immersion in water) is now used, allowing the desired moisture to be reached quicker. At the end of steeping the barley has a moisture level of around 45% moisture. (A 48 hour cylce will cycle through wet=>dry=>wet=>dry=>wet).

Question 10

How is germination carried out?

Answer 10

Traditionally, the barley would be spread over the floor of the malting house being turned regularly, typically every 2-4 hours, depending on the barley variety in use.

Nowadays, this is normally carried out on a commercial scale in large drums which rotate.

The barley is kept cool and moist and allowed to germinate in a controlled manner.

Question 11

When does germination occur in the 12 step barley process?

Answer 11

Germination is step 5, occurring after steeping (step 4).

Question 12

What happens to the barley during the germination process?

Answer 12

During germination, the cellular structure around the starch granules is partially broken down. A degree of protein breakdown occurs. A package of amino acides, enzymes and available starch is produced.The barley secretes the enzyme ‘diastase’ which makes the starch soluble, thus preparing it for conversion into sugar.

Question 13

How is the germination process halted?

Answer 13

By the kilning process.

Question 14

What is “monkey shoulder”?

Answer 14

It is a condition in which one arm hangs down a bit that was suffered by the malt-men as a result of the long shifts of constant manual work, including the turning of barley by hand.

Question 15

What is “green malt”?

Answer 15

This is the term used to describe barley after it has been germinated.

Question 16

What is the purpose of kilning?

Answer 16

Kilning ensures the germination process is arrested and ceased.

Question 17

What is done during the kilning process?

Answer 17

Hot air is blown through the bed of “green malt”. The green malt is then dried down to about 5% moisture, thus allowing for safe storage prior to use in the distillery. The dried material is now called malt or malted barley.

Question 18

At which stage in the barley process can peat be used to impart smokey/medicinal flavours?

Answer 18

During the kilning process. Peat reek can be passed through the wet green malt as the phenols adhere easily to their wet surface, therefore peat tends to only be burnt at the start.

Question 19

What is peat?

Answer 19

Decaying plant matter found throughout Scotland and in parts of Europe. It can be used to stop germination by drying the malt and imparting chemicals called phenols which are absobed by malted barley and impart a smoky flavour.
It is commonly used as a source of fuel for domestic fires.

Question 20

Describe in detail the structure of a kiln.

Answer 20

1. In a traditional kiln, the green malt sits on the perforated kiln floor.
2. Peat can be burnt for a smoky flavour.
3. Phenols from the peat reek adhere to the surface of the malt.
4. The hot air from the heat source (fire) passes through the grain bed by the natural circulation created by the pagoda roof.
5. As the hot air passes through the bed, the grain is dried, firstly for storage and ahead of used in the distillery.

Question 21

What is milling?

Answer 21

The process of grinding dried malt through giant rollers, creating a coarse flour called grist. Grist is made up of 3 fractions; husk, flour and grits.

It is usually the first production stage carried out at a distillery.

Question 22

What is Grist?

Answer 22

Grist is a product of milling and is made up of 3 fractions: Grits, Flour, Husk.

Question 23

Describe the features and function of the 4 roll mill.

Answer 23

Question 24

What is the importance of the milling process?

Answer 24

It helps distilleries achieve a maximum yield of alcohol from the malted barley and allows for easier processing.

Question 25

Why is the grist ratio a vital parameter for the distiller?

Answer 25

It tells them how well the malted barley has been ground in the mill. Each mashtun requires a certain ratio of husk to grist to flour, and the grist anaylsis tells the distillers if they have what we need for the efficient use of the mashtun.

A distiller can tell how good the grist is by sight and touch.

A grist analysis will also be carried out to determine the percentages of the various fractions in the grist.

Question 26

What is mashing?

Answer 26

The process of adding hot water to the grist. It takes place in a vessel called a mashtun and uses heat (hot water) to bring on the natural enzymes (amylase) to breakdown the starch in the grain and turn it into fermentable sugars.

Question 27

What is a mashtun?

Answer 27

The vessel where mashing takes place. It is made of cast iron or stainless steel. The bottom of the mashtun is effectively a sieve so that, after mashing, the sugary liquid (called wort) can drain through to the underback ahead of fermentation.

Question 28

Describe the mashing process.

Answer 28

The ground down grist, emerging from the malt mill is fed into the mashtun together with a charge of water heated to approximately 63.5°C. The temperature of this process is strictly controlled to allow for maximum conversion (although the exact figure varies between distilleries).

The sugars start to dissolve and produce a sticky, sugary liquid called wort. After a period of mashing, the wort is drained from the mashtun and collected in a tank called the underback.

Question 29

What is an underback?

Answer 29

The vessel used to store the wort which has drained from the mashtun before it is transferred to the washback for fermentation.

Question 30

How does the traditional mashtun compare to modern equipment?

Answer 30

In a traditional mashtun, the mash is mixed using rakes and paddles on arms that rotate around the edge of the tun. This is not as efficient as modern equipment as it mixes up the mash, thus breakig up the filter bed, instead of slicing through it in a controlled manner.

Question 31

What is sparging?

Answer 31

In the mashtun, sparging is a further charge of water added at a hotter temperature of up to 80°C. It is added to dissolve any remaining starch and sugars and is also drained through the underback and pumed into the washback.

A final charge of water - at a temperature of around 85°C - is added to the mashtun to dissolve anything worthwhile still left in the residue. The sparge is then drained off and is subsequently used as the first charge of water to be added to the next batch of grist.

Question 32

What happens to the wort after it is removed from the underback?

Answer 32

The wort can be over 60°C and must be passed through a plate heat exchanger called a wort cooler. This cools down the wort to around 16°C to 18°C (depending on ambient temperature), so that the yeast can be introduced without killing it.

Question 33

What is a lauter?

Answer 33

A type of mashtun design. It allows for speedier draining through more control than a traditional mashtun. It does this by raising and lowering the lauter arms as they rotate very slowly through the mash.

Question 34

What is draff?

Answer 34

The spent grain left in the mashtun after the wort has been drawn off into the underback. It is often sold on as cattle feed, or used in biomass burners.

Question 35

What is fermentation?

Answer 35

The natural process whereby yeast can metabolise sugar to release ethanol as a by-product. Basically, it’s the stage during the whisky production process when alcohol is made.

Question 36

What occurs during the fermentation process?

Answer 36

Once the wort has been cooled and starts being pumped into the washback, yeast can be added. Nowadays, yeast tends to be added in-line as a liquid along with the wort. Fermentation begins when the yeast converts the sugary wort into crude alcohol, producing a liquid similar in aroma and taste to a sour beer called ‘wash’.

Question 37

What is a washback?

Answer 37

The large vessel where fermentation takes place. Washbacks can be made of wood (Douglas Fir) or stainless steel.

Question 38

What is the temperture of the washback during the fermentation process?

Answer 38

The washback temperature starts at approximately 16°C to 18°C and will rise up to around 30°C.

Unlike brewing there has traditionally been no temperature control on the washbacks, with the starting temperature being the only control. A few distilleries have recently started to install a temperature control in the washbacks but this is still fairly unusual.

Question 39

What is wash?

Answer 39

The liquid produced from fermentation. It has an ABV of approx. 8-10% and is transferred to the wash still for the first distillation run.

Question 40

What is produced in the fermentation process when yeast metabolises sugar?

Answer 40

1. Heat
2. Carbon Dioxide
3. Congers
4. Alcohol/Ethanol

Question 41

How long does alcoholic fermentation normally take?

Answer 41

About 48 hours; yeast then starts to die.

However, many distillers ferment for much longre than this to allow for additional and different flavour congeners to generate by means of a natural ‘secondary fermentation’ from bacteria and wild yeasts.

Question 42

What is the importance of fermentation length in the production of a spirit?

Answer 42

It plays a part in the developing flavour compounds within the spirit.

Question 43

What characteristics are produced from a longer fermentation?

Answer 43

It is thought to produce a sweeter, fruitier wash.

Question 44

Which distillery has one of the longest fermentations?

Answer 44

Benromach at 115 hours.

Question 45

Which disterilly has a much shorter fermentation period?

Answer 45

Knockando at around 50 hours.

Question 46

What is common now for distilleries in respect to fermentation length?

Answer 46

Distilleries tend to operate partly with a long and partly with a short fermentation.