Mashtun

Mashtun is a vessel in the whisky production's mash-house, where malt is crushed and mixed with warm water to extract fermentable sugars and form wort, the sugary liquid that is subsequently fermented to alcohol.

Function and role in the process - Extraction of sugars from malt via enzymatic conversion in a warm water bath; malt starch is converted into fermentable sugars, providing the basis for fermentation and alcohol production. - The vessel also enables the separation of the solid residue (draff) and the wort to run off through a bottom or a false bottom (lautering).

Process and temperature conditions - Malt is crushed and mixed with water in the mashtun; temperature control is crucial for enzyme activity. Typical rest temperatures are around 65 °C, with the possibility of secondary rests between 60–70 °C depending on the desired sugar profile. - If needed, stepwise temperature control (step mash) is used to shift enzyme activity and convert more starch into sugars.

Design and construction - Mashtuns are traditionally cylindrical vessels equipped with a bottom or a false bottom and a drain for wort discharge; they can be made of stainless steel, copper, or other heat-resistant materials.

Related concepts - Wort: the sugary liquid that is extracted during mashing. - Draff: the solid residue left in the mashtun after draining. - Lautering: the process by which the liquid (wort) is separated from the solid mass.

Importance for whisky production - The efficiency of the mashtun affects the sugar profile of the wort and the amount of sugar extracted, which ultimately influences fermentation and the final alcohol yield and flavor profile.