How to select yeast
Posted by     09/17/2014 08:33:00    0 Comments

Selecting yeast for fermentation depends on your requirements and end objectives. When selecting a yeast, we normally work backwards from our end objectives and that will indicate how we should start and what type of yeast we should use.

The procedure to determine what kind of yeast to use, can be summarised (very simplified) as follows:

  • First of all decide on what your feedstock would be: Grain or sugar/fruit.
  • Then decide on the % alcohol you would like to achieve in your end distillate.
  • Determine whether this end distillate should be achieved in a single, double or even triple run. (Affecting the levels of flavour)
  • From this determine (using a water/ethanol phase diagram) what the alcohol content of your mash/wort should be for your particular still.
  • From this you can now select (depending also on your flavour requirements) which yeast would be suitable for your purposes using the following criteria:
  • Required alcohol potential of the yeast (to match your required alcohol content in your mash/wort).
  • Temperature range that you would be able to ferment at.
  • Then select the yeast with the lowest H2S production and lowest Nitrogen (nutrients) needs.

FOR FRUIT/SUGAR mashes/washes

The ideal yeast to start off with for the home distiller of fruit/sugar based mashes has following characteristics:

  • Fast fermentation rate in a wide pH range (i.e. 3.0 to 5.5)
  • High alcohol tolerance (i.e. 18% alcohol by volume)
  • Wide temperature tolerance (i.e. from 15 to 30 degree C)
  • Low H2S (hydrogen sulphide) production - the "rotten egg" smell
  • High sugar tolerance
  • Low production of SO2 (Sulphur dioxide)
  • Low or no foam production
  • Low initial oxygen requirement
  • Low assimilable Nitrogen requirement
  • Low production rates of volatile acidity and esters

The “Saccharomyces bayanus” strain of yeast is one of the most affordable, available and reliable strains of yeast suitable for distillers. It is also known as “Champagne yeast” and is commercially available as Lalvin EC1118.

Lalvin C, is perhaps the “best” yeast for high alcohol fermentations but not always readily available. If you can get hold of it, really give it a try! (see table hereafter)

The above being said: As you progress from home distiller to craft and boutique distilling, you will find that other strains of yeast produce less alcohol, but the resulting flavours might be much more appealing to you. Whisky production is rather sensitive to yeast selection and special “whisky” yeast should preferably be used.

FOR GRAIN MASHES: (maize, barley etc.)

Distillique stocks WD Whisky yeast with amyloglucosidase. This is a real Whisky yeast used by boutique and many bigger whisky distilleries. It will ferment beyond 8.5% Alcohol WITHOUT producing additional fusel oils and other unwanted byproducts. NO additional nutrients are required when using the WD Whisky yeast with a grain mash.

The WD Yeast is pre-mixed with amyloglicosidase enzymes to convert all non-fermentable sugars in the grains to fermentable sugars, during fermentation, at temperatures below 40 degree C. (Above 40 degree C the temperature destroys the Amylloglicosidase).

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