General Considerations

  • The extent of attenuation specified varies considerably across the industry. For a particular brand variations in attenuation should not exceed ± 1°
  • Fermentable sugars are required for active secondary fermentation
  • The time beer is stored in cask before despatch can affect levels of carbon dioxide.
  • Seasonal variations in ambient temperature will affect both fining action and rate of production of carbon dioxide
  • Sufficient carbon dioxide is required to give head to beer and for palate fullness

Range of Values

  • Gravity at rack should be between 1° and 3° above the attenuation limit. If storage time in the brewery is short, e.g. 2 days in summer, gravity at racking should be reduced.
  • Sufficient primings can be added to increase gravity typically by 1°.
  • The carbon dioxide content of the beer at dispense is typically 1·0 – 1·2 volumes.

Operational Protocols

  • Cooling of the fermentation should commence when the required gravity is obtained rather than after a set fermentation time.
  • The quantity of primings/finings used should be accurately measured by a dispense syste

Measurement Protocols

  • Attenuation limit should be checked regularly in laboratory tests.
  • Beer gravity should be checked prior to racking.
  • Beer gravity should be checked prior to despatch to ensure that secondary fermentation has started or taken place.