So let's have a look at what different kinds of yeast are used in whisky
production and what effect does it have?
Let's start with the basics - what is yeast?
"Yeast is a single cell organism which multiplies vigorously in the presence of oxygen and then after consuming all the oxygen will convert fermentable sugars into alcohol."
What's the difference between baker's yeast and distiller's yeast?
"Bread yeast is made to take a small amount of added sugar and along with some flour, slowly rise to make the tiny trapped 'bubbles' in the bread. Distillers yeast is made to ferment quickly and likes a lot of sugar to ferment into a lot of alcohol."
Most distilleries use Distiller's Yeast, some, like Bimber, use a combination of Distiller's and Baker's Yeast. Some have closed Washbacks, some have open or semi-open ones which allows some wild yeast to join the party. Some distillers deliberately use wild yeast - Glenmorangie Allta (Scots Gaelic for ‘wild’ and pronounced ‘al-ta’) was created from the yeast which grows wild on their own Cadboll barley.
Are there different kinds of distiller's yeast?
"Distillers yeast is a particular species of yeast (Saccharomyces cerevisiae) that has a particularly strong ability to metabolize sugar and produce alcohol as a by-product. Distillers yeast also has a major impact on the flavour of your final spirit. The flavour and aroma of whisky is highly influenced by the distillers yeast in the fermentation process and thus choosing the proper yeast has a significant impact of the quality of your distilled spirit. All distillers yeast is definitely not the same."
M Strain : For the 50 or so years up to 2003, the SWA obliged all Scottish whisky distillers to use the same DCL M-strain yeast, originally hybridized from Saccharomyces cerevisiae and Saccharomyces diastaticus during 1930s-50s by Distillers Company Limited a forerunner of Diageo. It was known by many brand names such as DCL M, M-strain, Quest M, Rasse M, M-1, D1 or WH301. Many distilleries still use the same strain to this day.
MX Strain : developed in the 1990s MX is faster and more efficient especially in high gravity worts which are preferred because of the savings in heating and water costs is a bit faster fermenter and produces a very similar flavour profile compared to the M. Some distilleries mix M and MX in their process.
Pinnacle : is an ethanol tolerant baker's yeast which works slightly faster than MX, reaching peak fermentation speed about 1 hour earlier than MX. This is used by many Islay distilleries.
Anchor DY 10 is an active dried distilling yeast recommended for use in the production of grain whisky by fermentation of wort made from wheat or maize, but is used by some malt distilleries e.g. Daftmill. This is usually delivered in a liquid cream.
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| Pinnacle Yeast as used at Tomatin. Photo: @WhiskynStuff |
Some of the yeast strains used in distilling are handed down through generations; others are wild, their use intended to reflect local terroir; but most are purchased. Which ever yeast is used it’s clear that it’s a key to unlocking a spirit’s flavour. Bourbon distillers for example use strains unique to their distillery, Four Roses have 5 strains of yeast and 2 mashbills, giving 10 very different new make characters.
How is yeast supplied?
Most yeast comes in dried powder format but is also available as a 'cake' or liquid cream.
How is yeast used?
Yeast is added to the wort in the washback after the barley has been mashed.
Glen Scotia for example add 75kgs of yeast : 2 bags of distillers M
Strain yeast and 1 of MX.
|
| Glen Scotia Mashman Bobby adds yeast to a washback |
The yeast gets to work turning the wort into beer ready for distillation. A
lot of a whisky's flavour is created during fermentation, a number of factors
including the amount of yeast used, temperature, duration, and the gravity
greatly impacts the resulting wash.
|
| Glen Scotia's Washbacks work over the course of 70 to 140 hours |
Yeast 'eats' the sugar in the wort and creates organic acids, ethanol
(alcohol), carbon dioxide and heat - all the time different flavours are
created. Initially yeast added to the wort starts to discover its new
environment – this is called the lag phase, it then starts to ‘bud’ or
reproduce asexually. The more sugar there is, the faster it grows and the
fermentation process speeds up. The yeast is continually breaking down sugars
and proteins into amino acids – the building blocks of flavours.
If you've ever put your nose into a bubbling washback you would have smelt an
strong unpleasant sour smell - this comes from acetaldehyde which is created
as ethanol is oxidised. Acetaldehyde is part of a group of compounds called
aldehydes which are created during the whole whisky making process - some are
good, some less so! Aldehydes can add many different taste notes to whisky -
sweet fruit, unripe fruit, vanilla, cinnamon, caramel, nut, malt and even
smoke! They serve as flavour congeners (compounds you can smell and taste),
and also play a part in creating compounds that add aromas. For example,
acetaldehyde can be further oxidised into acetic acid, this reacts with
alcohol to create an ester.
More than 100 esters have been identified in whisky they can be formed
during fermentation, distillation and maturation, but most are created
during fermentation, some are removed later in the process. Depending on
the type of acids and alcohols that are combined, esters can be classified
into short, medium, and long chain (classification depends on how many
linking parts they have!). Short chain esters introduce softer aromas like
bananas (isoamyl acetate) and cream (ethyl laurate). Medium chain esters
tend to be richer and fruitier, and introduce apples, grapes, cherries and
cinnamon notes. The longer chain esters tend to be more herbal and
incorporate some wood, waxy / doughiness and earthy elements.
During fermentation, longer chain fatty acid esters are produced by the
yeast during its growth cycle, which it uses to build cell walls. Once the
yeast dies, the cell walls break down and the esters are released back
into the wash. During distillation the copper in the skills catalyzes
chemical reactions which remove highly volatile sulfur compounds and help
form new esters that impart a fruity character. During maturation, acids
from the cask, which are a different lot from the acids formed in the
production process, react with alcohols in the whisky to produce even more
and different esters.
|
| Yeast acting on the wash |
Fermentation times of less than 50 hours is considered short, 60 to 75 hours
average and 75 to 120 hours long. Longer fermentations of over 55 hours with
standard distiller's yeast will produce little or no more alcohol, but the
longer fermentation gives more flavour and tend to produce a wash that's
easier to distill as they have less of a tendency to foam.
After around 50 hours the yeast will have does it's job, all the sugar
is used up and the yeast dies, the resulting distilled spirit will tend
to have a cereal taste. Longer fermentation times, starting around 48
hours after the yeast has died, take advantage of lactobacillus
bacteria. These begin to act on the wash, some feed on the dead
yeast cells, others attack sugars which the yeast cannot convert, others
only come to life after 70 hours when the acidity is higher; they
all help to generate new fruit flavours resulting in a more complex
spirit.
Chardonnay Wine Yeast
Some distillers have experimented with wine yeasts with varying levels of
success as it gives a lower ABV - Michael Henry at Loch Lomond has been
experimenting with different strains of wine yeast since 2004 with varying
success, some strains give more flavour impact :
"Wine yeast is used to growing on the nutrients from grapes which are different to the nutrients from malted barley - it isn't able to utilize all the sugars from the malted barley so gives a lower amount of alcohol. The ABV coming off the stills will be the same but the volume of alcohol recovered will be lower i.e. you will get less new make spirit for the same weight of malted barley compared to a fermentation with one of our normal yeasts."
but what you are doing is accepting:
"the trade off for flavour over yield"
So what difference does Chardonnay Wine Yeast make to the flavour of the
resulting whisky? For me they've all had this effervescence on the tongue
as the liquid disappears - yummy! Let's find out!
A batch of whisky, from a single washback using wort to which Chardonnay
Wine Yeast was added, was distilled at Loch Lomond's distillery in
Alexandria, North of Glasgow, on 19th December 2007, using Straight Necked
Pot Stills fitted with a cooling head, taking a narrow cut of the spirit
at a high collection strength 90-80%. The spirit was matured in refill
American oak hogshead and has found its way into 4 different whiskies that
I can find:
| 2007 Inchmurrin Single Cask #5834 |
2007 Inchmurrin Cask Sample |
Cider and cedar 2007 SMWS 112.22 (Inchmurrin) |
Loch Lomond 12yo Open Special |
|---|---|---|---|
|
|
|
|
| 9yo | 10yo | 10yo |
12yo |
| 58.4% | 54.8% | 59.9% | 46% |
| American Oak casks | Refill Bourbon then 1st Fill Sauternes Finish (2yrs) |
Second Fill Ex-Bourbon Hogshead | American refill oak casks |
| 276 bottles released in 2017 | The #BlindTastingOnTour gang tried this at the distillery in 2018 | 261 bottles released in 2017 | 3,000 bottles released in July 2020 |
What are the whiskies like?
Obviously the Cask Sample 2007 Inchmurrin doesn't have any
official tasting notes and I can't remember too much of the detail from that
day..... so it's not in the table below!
| Dram |
2007 Inchmurrin Single Cask #5834 |
Cider and cedar 2007 SMWS 112.22 (Inchmurrin) |
2007 Loch Lomond 12yo | |
|---|---|---|---|---|
| Distillery notes |
Creamy sweet fudge, some butterscotch and marzipan. There is pineapple juice and lemon zestiness finishing on mild oak spices. The 2007 Inchmurrin cask 5834 is from our Chardonnay Wine Yeast Fermentation spirit. |
A medley of ripe apples, cinnamon sticks and vanilla pods nestled
amongst fragrant aromatic cedar garland spread some festive cheer
amongst the Panel members. On the palate sweet and spicy to start, cider-brined pork chops with ginger and nutmeg spiced apples, followed by classic French beurre noisette and a dry finish of hazelnuts. With a drop of water we were making pecan, cinnamon and maple syrup steamed sponge pudding next to pots of melting copper pennies and to taste cinnamon buns, spicy custard, tinned peaches and lemon-frosted pistachio cake whilst drinking dry cider out of an antique cedar tankard. |
A 3,000 bottle Limited Edition created from a Chardonnay wine
yeast which adds a lively, almost effervescent mouthfeel, with
additional fruit characteristics like grapefruit and tart green
apples with a finish of powdery sherbet and lime juice. Nose: Grapefruit, apple and vanilla syrup. Palate: Lively almost effervescent mouthfeel. Honey sweet, green fruits – apple, pear and kiwi, gentle cinnamon spiciness. Finish: Long finish with powdery sherbet and lime juice. |
|
| My thoughts: | ||||
| Appearance |
|
|||
| Light gold in the glass, swirls form thick lines in the glass and fall as slow thick legs. | Very pale gold almost white wine. Swirls form a hairline crack, bead up and fall as slow thin legs. | In between the first two, a pale gold colour. Swirls again form a hairline crack, bead up and fall as slow thin legs. | ||
| Nose |
The sweet fruity nose of a typical Inchmurrin is here - orchard
fruit, honey and cereals but with the added notes of grapes and
vanilla ice cream. A little time and air offers Maltesers, butter and apricots. There's a little cinnamon spice too. The ABV doesn't hide - it's straight up your nose! |
Lives up to its name - cider and wood notes - not sure I can tell
the difference between cedar and oak - but it's definitely woody! As
well as the apples there's some pear and pineapple. There doesn't seem to be as much sweetness on the SMWS but there is the cinnamon spice. Again the ABV doesn't hide! |
Sweet stewed orchard fruit - apples, pears, apricots covered
in vanilla custard. There's lots of malty cereal, sour citrus and
wine notes. Assuming this is an older, diluted #5834 it seems to have lost the chocolate notes and developed some tropical fruit ones. A little time in the glass and tropical fruit notes develop. |
|
| Palate |
Smooth thick arrival, toffee and honey to start with before tongue
gets assaulted by a sharp lemon fizz. There's some malty nutty
cereal notes (Alpen?) and a little brown sugar. A little time and a few more sips offer the orchard fruit notes from the nose and a hint of fruit and nut milk chocolate. |
Smooth thick sweet arrival, instantly drying, coating the
mouth. Orchard fruit - apples and pears with a little toffee
and sweet honey. Brown sugar notes. The citrus fizz is here but it's not as intense. Very warming, the ABV again making itself felt. |
Smooth sweet arrival - tropical fruit and a gentle peppery spice.
Dried pineapple and kiwi. There's the lemon fizz on the tongue and a
slightly drying icing sugar note. Very warming - suggesting an ABV
higher than it's 46% The liquid disappears leaving a lovely sour grapefruit note in the back of the throat. |
|
| Finish | Lingering toffee and peppery spice - hints of orchard fruit and citrus fizz. Very drying. | Lingering brown sugar sweetness and a peppery spice. Drying. | Medium length toffee and gentle peppery spice - drying citrus. | |
| Overall |
All of these were matured in refill casks meaning there was little
effect on the maturing whisky - the colour shows that too - the
spirit has been left to gently evolve with a minimum of wood
influence letting the distillation flavours come to the fore. The two younger drams #5834 and 112.22 share typical Inchmurrin sweet orchard fruit notes and a little nutty cereal but the older diluted 12yo turns this more tropical. They all have a citrus fizz on the tongue, an effervesce that's stronger on the two higher ABV drams but also there to a slightly lesser extent on the 12yo. The 12yo definitely punches above its 46% but it's not quite up to the cask strength flavours of the other two, it does add a lovely sour grapefruit note which I love. The younger drams have a more biting dryness and a more lingering finish - winter fireside drams, I'd suggest the 12yo is better suited to summer BBQs - dangerously drinkable! As a preference I'd probably go #5834, 12yo then 112.22 but there's not a lot in it! |
|||
Many thanks to @chris_f74 for
the sample of SMWS 112.22.
There is also the 2009 SMWS 135.22 (Inchmoan) - from a second distillation
batch using Chardonnay Wine Yeast but this time using Swan Neck Pot Stills
rather than Straight Necked and as far as I can tell it isn't peated - SMWS
confusing us with their number codes again! Loch Lomond are yet to release
anything from the 2009 distillation so we'll wait and see!
You can read my blog on Oak
here!
Appearance: Pale gold in the glass, swirls cling, form an inverted grown of beads and fall as slow thin legs.
Nose: more fruity than the 46%, the fruit notes are enhanced. ABV attack the nose! A little air and some musty dunnage notes.
Palate: Huge peppery spice bite, tropical fruit and a lemon fizz on the tongue.
Finish: long lingering peppery spice.
Update Feb '21 / Dec '22 / May '24
I've found another few releases which used Chardonnay Wine Yeast!
30% of the spirit in The Open Special Edition 2018 was fermented using CWY.
A 2010 single cask released for The Whisky Exchange used CWY
| Open Special Edition 2018 | 2010 10yo Single Cask #349 |
Distillery Edition 1 2010 9yo Single Cask #119 |
Distillery Edition 5 2015 8yo Small Batch |
|---|---|---|---|
|
|
||
| NAS | 10yo | 9yo | |
| 46% | 57.7% | 57.1% | 59.1% ABV |
| American Oak casks | Refill Bourbon |
Ex-bourbon | |
| 30% of the spirit in The was fermented using Chardonnay Wine Yeast. | Exclusive to The Whisky Exchange 241 bottles |
Review here! | Review here! |
Roy @Aquavitae has also had 3 releases:
| 2011 10yo Single Cask #735 | 2011 12yo Single Cask #736 | 2014 14yo Single Cask #118 |
|---|---|---|
|
|
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|
| 10yo | 12yo | 14yo |
| Ex-Bourbon | Ex-Bourbon | Ex-Bourbon |
| 54.9% ABV | 53.3% | 58% |
| Review here! |
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