is a practical alternative to liquid yeast that offers many advantages to the brewer. Many brewers, particularly craft brewers, retain a prejudice against dried yeast because the quality of dried yeast was quite poor during their amateur days. Today, the products available are greatly improved. Dry yeast averages 95% dry matter and 1 g contains between 0.5 and 2 × 109 live cells, depending on the strain. Yeast cultures are grown using a batch (all sugars are added at once while the yeast is fermenting) and then a fed-batch system (the sugars are added slowly so that the yeast produces biomass and not alcohol) and then dried using a fluidized-bed dryer (the yeast remains in suspension in warm air), which is gentle on the yeast. The production process is carefully optimized for each strain so that the yeast will recover and perform adequately in fermentation once rehydrated according to the manufacturer’s instructions. Because dry yeast is produced in the presence of large amounts of air, there is no need for aeration/oxygenation prior to inoculation. The quality of dry yeast has advanced because of extensive quality control put in place by the manufacturers; viability and vitality measurements, contamination levels, and genetic integrity are among the tests being performed routinely.

There are numerous advantages to using dry yeast, the most important being a long shelf-life of up to 2 years, non-refrigerated transport, and easy dosage. Dry yeast can be used as a starter for propagation or pitched directly into fermentation and subsequently reused successfully for many generations. The use of dry yeast for bottle conditioning is becoming increasingly popular because of the number of strains available in dry form (brewer’s, wine, and distiller’s yeast) and the consistency of the product, which in turn can give reliable results. Dry yeast can also be used randomly as emergency stock or to restart a stuck fermentation.

See also yeast.