Malt Distilling

Question 1

When ?

Answer 1

It occurs after fermentation. So barley with or without an alternate cereal is malted, milled and mashed to produce a wort ( adjuncts may or may not be added at this stage ), no wort boiling is done like in the case of brewing. Wort production is followed by immediate fermentation ( This means that certain enzymes will still be acting up unlike in brewing which are stopped by wort boiling process). Grain and GNS is added at the stage of malt whisky . distillation. This is followed by maturation and packaging. Distillation process can be used to rectify problems.

Question 2

Process?

Answer 2

Done to sep volatile comp from non vol comp. ( fundamental of distillation)

Batch distillation in copper pot stills.
To separate alcohol from the wash.

Question 3

Wash

Answer 3

Wash is basically the distilling version of wort. Making a wort means making a wash. So after fermenting it, it becomes wash.
Malt whisky is on the premium end of the market and hence constitutes of only a small percentage of the markert. Blends can consist of vrious numbers of single malts which will eachhave their own sep characteristic.

Question 4

Production

Answer 4

• Not linear
• products of one stage are fed into previous stages to maximize yeild.
  -pot ale and spent less need treatment ( then discared )
  DDGS??????
  (REFER TO DIAGRAM IN SLIDES)

Question 5

Pot Ale

Answer 5

Received as a co=product from wash still

Also, the pot ale is hot. use heat exchanger to heat the next batch. ( circular economy , to reduce the energy consumption , cost and waste disposal issues)

Wash pre-heater

Question 6

Spent lees

Answer 6

received as a co-product from the spirit still.

Question 7

Low wines

Answer 7

• low ABV
• dissolves more copper because has more sulpher content

Hence low wines are taken and then distilled again in a copper pot still, this is because the low wines that have taken up copper rich now. Hence we are really concentrating the copper content

Question 8

Foreshots

Answer 8

Contain :

• strongest in alcohol
• methanol
• long chain FA
• Other compounds that affect flavor and clarity.

But since they contains too much alcohol to throw away. Recycle. put in low wines in next batch of spirit distillation.

Question 9

Volumes

Answer 9

100 vol wash will give:

• 65 vol pot ale (<0.1% abv)
• 35 vol low wines ( 19-22.5% abv)
• 20.5-23 vol foreshots/feints( 28-30% abv)
• 10-11.5 vol spirit (68-70% abv)
• 23.5-24.5 spent lees ( <0.1% abv)

Question 10

Volumes

Answer 10

100 vol(7-8% abv) wash will give:
- 65 vol pot ale (<0.1% abv) ( v. less alcohol wasted)
-35 vol low wines ( 19-22.5% abv)
-20.5-23 vol foreshots/feints( 28-30% abv)
- 10-11.5 vol spirit (68-70% abv)
-23.5-24.5 spent lees ( <0.1% abv)
(DIAGRAM)

All alcohol wasted affects costs ultimately

Question 11

Design of pot still

Answer 11

-copper ( malleable, good conductor of heat and helps in flavour control)

flavour is controlled by take up of sulpher compounds.

malleablity may be worse , because needs to be get in shape again and again - cooperage

• different heat sources possible ( solid fuel, steam, gas)- mostly steam heated by using oil as fuel.

Question 12

Parts of a pot still

Answer 12

-swan neck ( descending and ascending lines - changes the level of reflux)–> bulbous nexk and upward inclined lyne arm - increases reflux

purifier maybe included in lyne arm to increase reflux.

• OG??
• Spirally thing - condensor ( has a cylinder over it to cover it )

rectifying plates used in swan neck to increase reflux,

Glenfiddich have an open fired still

Question 13

Swan neck

Answer 13

• varies ( short to long)
• base can be designed to resemble ball, ;antern glass, onion
• has two sight glasses at opp ends ( to observe foaming if any )
• ligh tat rear sight to illuminate internally
• cold finger can be installed ( prevents foam from boiling iver into the receiver.
• vaccum relief safety vale - to be situated well above the foaming distillate in wash still to avoid seizure of valve seat by solids

Question 14

Head

Answer 14

Curved extension of neck

connected to lyne arm

can be fitted with a thermometer to indicate the arrival of condensate

height / length influences degree of reflux

Question 15

Lyne arm

Answer 15

connects head to condenser ( can be worm or shell and tube type)

has an important affect on spirit characteristic

ascending/descending/horizontal. Also, long or short. affects nature of new spirit

can/maybe fitted with a purifier - encourages higher FA esters to return to still during distillation. returns these oils to shoulder of the still.

Question 16

Worm tub and shell and tube

Answer 16

long coiled tube tapering to a nominal outlet.

supplied with cooling water which enters at the base of the tub and overflows at the top. At certain times when supply of water is insufficient - for these times attach cooling tower/heat plate exchanger.

Shell and tube is the more advanced version of the same thing. Also, a plate heat exchanger fitted with copper plates.

Question 17

Spirit Safe

Answer 17

• monitor and control the cut point, strength and temp of outflowing condensate prior to delivery to relevant receiver.

hydrometers can be used to determine the strength of low wines from wash still or foreshots, middle cuts and feints from the spirit still

Question 18

Wash still

Answer 18

monitored by narrow range hydrometer to determine the completion of wash distillation

Question 19

Spirit still

Answer 19

Controlled by two hydrometers, tail pipe outflow is directed to one of the collecting bowls ( one for foreshots and feints and one for potable spirit.

has an annualar heater for increasing heating capacity. They add more mass and surface to ti the coil.

Question 20

Wash still operation

Answer 20

• fermented wash with OG 1050-1-60 transferred to the wash charger for preheating( energy intensive process) [ by heat transfer from previous pot ale]
• make sure discharge valve is closed and charging and air valves are open
• anti collapse valve should be moving freely
• charge vol heated with direct or indirect firing
• preheated wash is bought in to the wash still
• charging and air valves to be closed when the still has been charged to an apt vol
• man valves closed
  ( valve automation preferred to avoid accidents)

Question 21

Spirit Still Operation

Answer 21

Spirit still is charged to no more than 2/3rd of the vol.

Same precaustions regarding the valved to be taken as in the wash still

charge Ingredients are a mixture of foreshots, low wines and feints. ( low wines and feints are not pre-heated)

Divided into three fractions

1. Foreshots
2. Middle cut
3. Feints

Question 22

Foreshots

Answer 22

first runnings of the spirit distillation and in most cases not worthy of collection as potable spirit.

high proportion of highly volatile and flavoursome compounds. Eg. Ethyl acetate.

15- 30 mins

When the distillate drops to 75% abv.

Demisting test is carried out

heat applied to the foreshots effects the distil during the spirit distillation and effects quality. too harsh application of heat will result in fiery spirit quality. delicate application is to be preferred to avoid adverse flavour notes .

Question 23

Demising test

Answer 23

This involves mixing foreshots with water in hydrometer jar in the safe and reducing the strength of the mixture to 47.5% abv

initially turbid due to displacement of water-insoluable residual long chain fatty acids and their esters ( remained in the spirit condensor from prev distillations)

When mixture of foreshots and water clears - deemed potable. transferred to the feints receiver and from their to the spirits receiver,

2.5-3 hours

These days, the test might npt be carried out but distillers might just to do this on the basis of time

strength drops from 72 to 60% abbv.

Question 24

Middle cut

Answer 24

to be heated gently like foreshots to avoid adverse flavour effects. collected at 60 abv

Question 25

Feints

Answer 25

can be treated like wash distillate. reach end of distillation at 1 abv. the resulting resiidue ( spent less) can be discharged) After this, the spirit still is to be discharged. chemical cleaning rarely nec. and should be avoided to protect internal.

Question 26

More on spirit still

Answer 26

- sulpher comp present in distillate vapour ( highly volatile and odorous)--> take their toll on copper forming sulphides - co2 in wasg encourages formation of copper carbonate - attacks by sulpher and co2 may also thin the stills at shoulderm swam=n neck, lyne arm and condensor tubes that are exposed to the vapour , hence stills need often patching and even eventual replacement.

Question 27

Worm tub

Answer 27

traditional not much copper contact(heavy spirit character) no heat recovery prone to leakage

Question 28

Shell and tube condenser

Answer 28

modern high copper contact ( light spirit character) heat recovery possible spirit cooler removes sensible heat

Question 29

ABV vs Distillation time

Answer 29

cut points - crucial part of the recipe ( refer to the graph on slides)

Question 30

ABV vs Distillation time

Answer 30

cut points - crucial part of the recipe ( refer to the graph on slides) goes from low to high abv because when we go from one batch to the other , abv is dropped off, there would be material from the previous run that would be carried over to the next run, this contains water and long chain FA ( main reasons foreshots exist.

Question 31

Congener profiles in the spirit still

Answer 31

high volatility congeners in the foreshots. Also, ability to dissolve in alcohol and water. The main solvents are these two. The reason why one congener may be present will be influenced by its solubility in these two.

Question 32

FIRST CUT

Answer 32

first cut too early , contamination by fusel oils from previous distillations, ethyl acetate and other highly volatile esters too late, ethanol accumaltion in foreshorts ( WASTAGE) Hence imp when make cuts

Question 33

SECOND CUT

Answer 33

too early 0 lighter spirit produced too late - spirit contamination by faints. ( stake notes and metallic after taste)

Question 34

Analysis of new make spirit

Answer 34

Ethanol acetaldehyde ethyl acetate diethyl acetate etc etc

Question 35

By-products

Answer 35

Pot ale and spent lees pot ale ahs high BOD ( this is combined with spent grain and dried to give dark grain, spray on farmland or turn into fish food. ( discharged into sea earlier) spent lees has low BOD , it is treated in an effluent plant and discharged to the sea.

Question 36

Role of copper

Answer 36

- formation of desirable congeners and removal of undesired ones. - removal of sulphur containing comp - influenced by still and condenser surfaces

Question 37

removal

Answer 37

- dimethyl trisulphide contribute to stagnant rubbery flavour and aroma - presence depends on so2 in kilned malt - h2s and so2 can influence yeast metabolism hence is glass used, this will be predominant. Every time distillation occurs, more and more of copper is dissolved hence the patching and eventual replacement

Question 38

Copper removal

Answer 38

prevelant in pot ale and spent lees ( more in spent less) in spirit is low anaerobic and aerobic treatment of spent lees and other effluents concentrates the Cu in the sludge when sprayed on farmland, builds up in soil and can eventually run off into water courses. Due to this high Cu amount one should prefer to bury it than spraying other treatments include: - lime treatment - ion exchange + acid addition+ electrolysis of eluate - cross flow filtratio n+ acid addiction to permeate + electrolysis

Question 39

Factors that affect product quality

Answer 39

``` Barley malt kilning conditions(peat etc) wort that should be fully attenuated and fermenting for at least 48 hours. wash still charge shouldnt exceed 2/3rd vol wash preheating if not charge to to be heated lightly initially. water ( process, product, service etc) air cut point not less than 60% rate of distillation ( not too rapid) proper cuts adequate reflux ```