Comparison of Two Brewer’s Yeast Strains Serial Re-Pitched during Beer Fermentation
Makayla Weeks, Abigail Wills, Anna Belle Kratz, John Michael McCranie, and Melissa Hayes
Brewing beer involves maintaining consistent profiles and understanding how different yeasts influence flavor. Pure, mixed, or spontaneous strains can be selected for brewing, depending on the desired beer characteristics (Willaert 2007). Pure yeast strains are typically used, but mixed cultures are used for some specialty beers (Maicas 2020).Ale yeasts (Saccharomyces cerevisiae) are commonly used Brewer’s yeasts (Botstein and Fink 2011). Yeast breaks down carbohydrates in the malted barley in hot water, activating enzymes that degrade starch and proteins, producing the wort. Hops are then added to act as an antimicrobial agent and to contribute to the bitterness of the resulting beer. Knowledge of Saccharomyces is well developed (Botstein and Fink 2011). However, we can find no studies that compare cell counts after serially re-pitching individual or blended yeast strains. Our study aims to examine the cell counts of second and third generation brewer’s yeast cultures. The cultures studied were Irish Ale and Pacific Ale yeast strains as well as a mixed blend of the Irish and Pacific Ale yeasts. We hypothesized that the pure cultures will have a higher third generation yeast cell count than the mixed blend because pure strains will face reduced competition between species.
Makayla Weeks is a senior biology major with a minor in chemistry. She is a member of the TriBeta National Biological Honor Society. Makayla plans to attend medical school after graduating from Lander.
Abigail (Abby) Wills is a senior biology major with a pre-veterinary emphasis and minors in chemistry and psychology. She is a member of the Lander University Honors College, TriBeta National Biological Honor Society, and Alpha Chi National College Honor Society. She will be attending the University of Georgia College of Veterinary Medicine after graduating from Lander in May 2022.