OUR PROCESS
MASHING
MALTING & FERMENTATION
At The Glenfiddich Distillery we use the finest malt from specialist maltsters, produced to our own specification. Ripe barley is steeped in water for two days, which triggers germination. The barley is then left to germinate for four to five days, which starts the conversion of natural starch into sugar. The resulting 'green malt' is dried over fire, and delivered to the Distillery as malted barley.
INSIDE THE MASH HOUSE
Two of Glenfiddich single malt Scotch whisky’s essential ingredients - malted barley and soft clear water - are brought together in the mash house. The malted barley is ground into 'grist' - a coarse flour that is mixed with heated pure Robbie Dhu spring water from the nearby Conval Hills and then poured into giant 'mash tuns'. Here a slowly rotating set of mash knives lift and sift the mash to ensure good sugar drainage. In the mash tuns, the natural bubbling chemistry and clouds of steam rise, filling the air with a pleasantly pungent aroma. The hot water completes the conversion of starch to sugar, which dissolves into the water, producing a sweet liquid called 'wort', some six hours later. The wort is drained, cooled and made ready for fermentation. The 'draff' - the left over barley from the process - is sold to farmers and fed to their cattle.
FERMENTATION IN THE WASHBACKS
Yeast is added to the wort as it is pumped from the cooler into the traditional wooden fermentation vessels, the 'washbacks'. Our handmade washbacks are made of Douglas fir rather than the stainless steel that many other distilleries use. This traditional method of production is kept so as to not alter the flavour of the whisky. These washbacks are a towering 17 feet high (5 metres), and are filled to within 3 feet (1m) from the top. As fermentation raises the temperature from around 19°C to about 33°C, the resulting carbon dioxide gas creates a massive, hot frothing head to the wort that foams up the remaining 3 feet (1m) to the top of the washback and has to be kept down with mechanical beaters.
After around 64 hours of fermentation, the furious bubbling subsides, leaving a brown liquid of 8-9% ABV, similar to a strong beer - the 'wash'.