General Considerations

  • Yeast from fermentations should be carefully selected and stored so as to maintain a continual supply of pitching yeast
  • Temperature and time of storage should be controlled to produce pitching yeast of consistent quality (viability, homogeneity and composition).
  • Requirements for pitching yeast may vary according to brewery operations, production targets and whether pitching yeast is supplied to other breweries.

Range of Values

  • Ideally yeast is reused within 48 – 72 hr Some yeasts need to be stored for a minimum of 24 hr. Storage time should not exceed 7 days.
  • Storage temperature is 1° – 4°C (34° – 39° F) It should be noted that the temperature of the yeast room and that of the yeast itself can differ markedly particularly with compacted pressed yeast or concentrated slurries.
  • Yeast is stored as pressed yeast (20 – 27% dry matter) or as a slurry (ca. 10% dry matter)

Operational Protocols

  • The yeast press or receiving vessel should be cooled to 1°C (34° F) to maintain yeast at low temperature and/or reduce temperature as quickly as possible.
  • Handling plant must be adequately cleaned and sterilised. Where possible siting of yeast presses should be carefully chosen to minimise pick-up of air-borne contaminants.
There are several methods of operation depending on the type and size of fermenters and the method of cropping used. Some examples are:
  1. Yeast from the fermenler is passed via a filler press to a mixing vessel, reslurried with water and stored at 2° C (36° F) with stirring
  2. Yeast from the filter press is stored as filter ‘cake’ on trays in a cold room at 1° – 4° C (34° – 39° F).
  3. Yeast from the fermenter is stored as yeast slurry under beer at 2°C (36° F).
  4. With cylindroconical vessels yeast is often transferred directly from one vessel to another.

Measurement Protocols

  • The temperature of the yeast during storage should be checked.
  • Viability, composition, percentage dry matter and contamination of yeasts are measured as described in The State of Yeast at Pitching