Yeast Count at Fining
• Finings action depends on the yeast count, yeast viability and its flocculation/sedimentation characteristics and may be affected by the presence of infections.
• Finings action also depends on the temperature at fining and the carbon dioxide content of the beer.
• It is important that the yeast count in each cask is similar. It may therefore be necessary to rouse beer in settling tanks or Racking Backs in order to prevent higher yeast counts near the bottom of the tank. This will depend upon the flocculation/sedimentation characteristics of the yeast strain and the time taken to rack the vessel.
Range of Values
• For reliable fining yeast counts should fall within the range 0·5 x 106 – 2 x 106 cells per ml.
• Typical yeast counts for bright fined beer lie in the range of 100 – 1,200 cells per ml.
The yeast count can be controlled by:
• Racking beer fromthe fermentation vessel following cleansing.
• Centrifuging a proportion of beer after fermentation to give the required value. Alternatively beer is centntuged to give a low yeast count and an appropriate amount of yeast added back to give counts in the range of 0·5 x 106 – 2 x 106 cells per ml.
• Samples of every brew should be checked for cell count and the presence of infections.
• Periodically the brews should be tested for yeast flocculalion characteristics and viability.