Some yeast strains are more active and vigorous than others. Lager Strains in particular do not show as much activity on the surface as many of the Ale strains. We provide an adequate quantity of yeast to complete fermentation with varying amounts of lag time depending on the strain, freshness, handling, and temperature. If you find it too slow, make a starter as recommended on the package. In any event, a closed fermenter with an airlock is recommended.
The slow onset of visible signs of fermentation can be improved by starting fermentation at 75F until activity is evident, then moving to your desired fermentation temperature. A few degrees does make a significant difference without adversely affecting flavor. The normal temperature for Ale yeast range from 60 – 70:F. A few strains ferment well down to 55:F. 68:F is a good average. Lager strains normally ferment from 32 – 75:F. 50 – 55:F is customary for primary fermentation. A slow steady reduction to 32:F during secondary fermentation typically works well. The fermentation rate is directly related to temperature. The lower the temperature, the slower fermentation commences. Fluctuations in temperature such as cooling and warming from night to day can adversely affect yeast performance.
Apparent attenuation of yeast normally ranges from 67 – 77%. The attenuation is determined by the composition of the wort or juice and the yeast strain used. Each yeast strain ferments different sugars to varying degrees, resulting in higher or lower final gravities. This will affect the residual sweetness and body.
All brewing yeast flocculate. This degree and type of flocculation varies for different yeast. Some strains clump in to very large flocculate. Some floc very little into a more granular consistency. Most yeast strains clump and flocculate to a moderate degree.
Typical pH range for yeast fermentation begins at about 5.1 and optimally 4.8. During the course of fermentation the pH reduces to typically 3.9 – 4.1 and as low as 3.1 iin some wines.
The alcohol tolerance for most brewing yeast is at least 8%. Barley wines to 12% can be produces by most Ale strains. Pitching rates need to be increased proportionally to higher gravities. Alternately, Champagne and Wine yeast can be used for high gravities sometimes reaching alcohols to 18%.