Scott Labs Yeast Choosing Guide
Last Updated: 7/2021
Applies to: Winemakers looking for assistance in selecting and comparing Scott Labs yeast strains. This guide contains downloadable pdf choosing charts (see end of article) that characterize our yeasts by fermentation kinetics, sensory impact & recommended variety.
Selecting Yeast for Success
What to consider when choosing a yeast
Harvested grape lots can differ from vintage to vintage and from block to block even within the same vineyard. There is no such thing as “standard” fruit chemistry and you can improve your yeast selection success by knowing the fermentable sugar, yeast assimilable nitrogen (YAN), and physical condition for every lot of fruit. Knowing the pH, titratable acidity (TA), malic acid and potassium concentration for each lot is also helpful for your entire winemaking plan. We suggest selecting yeast based first on its technical compatibility with grape and winery conditions and secondly on its sensory contribution and compatibility with the desired wine style. As a reminder:
Fermentable Sugar
Yeast strains vary in their ability to tolerate ethanol levels. The initial sugar content will help determine the final ethanol content. Initial sugar content may be determined by gravity (usually reported as °Brix) or by direct measurements of sugar.
YAN
Yeast strains vary in their need for yeast assimilable nitrogen (YAN). Our strains are classified as low, medium or high nitrogen-demanding strains. The amount of nitrogen a yeast will need is dependent upon its individual needs, the initial sugar level and the temperature of the fermentation.
Temperature
Yeast strains vary in their temperature tolerance. Do not stress the yeast by fermenting at the upper or lower end of the recommended range. Temperature management is a key factor of yeast health, fermentation rate and security. Temperature should be measured directly under the cap in red must/wine and good cap management is required to ensure homogeneous temperatures. When working with high sugar fermentations, lower temperatures are recommended.
Sensory Impact
Yeast contribute to wine aroma, flavor and mouthfeel. Some strains enhance varietal characters increasing fruity, tropical, spicy and floral notes. Other strains can produce esters increasing fruity and floral aromas. Certain strains produce polysaccharides and other compounds increasing mouthfeel. Lastly, some strains have a neutral sensory impact thereby preserving inherent grape qualities.
