Comparison of Media for Intermediate-term Storage of Brewer's Yeast
Location
CSU Ballroom
Start Date
10-4-2018 10:00 AM
End Date
10-4-2018 11:30 AM
Student's Major
Biological Sciences
Student's College
Science, Engineering and Technology
Mentor's Name
T.E. Secott
Mentor's Department
Biological Sciences
Mentor's College
Science, Engineering and Technology
Description
The number of microbreweries has been increasing in Minnesota over the past decade. To make these businesses economically viable, many microbrewers have begun to maintain their own stocks of yeasts. How these yeasts are stored can have an effect on the quality and turn-around of the resulting beer. One form of yeast maintenance is through cryopreservation, in which yeasts are frozen in an appropriate storage medium. However, which media are appropriate for yeast storage have not been established, nor is it clear that storage conditions for one yeast strain would be appropriate for all strains. We stored two strains of yeast (ale yeast and lager yeast) in three different freezing media - wort broth (WB), CryoBroth (CB), and OxyStasis (OS) - and assessed the viability of the yeasts in these media at several time points over a four-month period by flow cytometry. Viability was determined using Viacount reagent, which labeled viable cells fluorescent green and nonviable cells fluorescent red. Ale yeast retained 90% viability in CB, 40% viability in OS, and < 10% viability in WB. In contrast, lager yeast retained > 80% viability in all media. We conclude that no one medium is best for intermediate-term storage, and the medium most appropriate for storage should be determined experimentally.
Comparison of Media for Intermediate-term Storage of Brewer's Yeast
CSU Ballroom
The number of microbreweries has been increasing in Minnesota over the past decade. To make these businesses economically viable, many microbrewers have begun to maintain their own stocks of yeasts. How these yeasts are stored can have an effect on the quality and turn-around of the resulting beer. One form of yeast maintenance is through cryopreservation, in which yeasts are frozen in an appropriate storage medium. However, which media are appropriate for yeast storage have not been established, nor is it clear that storage conditions for one yeast strain would be appropriate for all strains. We stored two strains of yeast (ale yeast and lager yeast) in three different freezing media - wort broth (WB), CryoBroth (CB), and OxyStasis (OS) - and assessed the viability of the yeasts in these media at several time points over a four-month period by flow cytometry. Viability was determined using Viacount reagent, which labeled viable cells fluorescent green and nonviable cells fluorescent red. Ale yeast retained 90% viability in CB, 40% viability in OS, and < 10% viability in WB. In contrast, lager yeast retained > 80% viability in all media. We conclude that no one medium is best for intermediate-term storage, and the medium most appropriate for storage should be determined experimentally.
Recommended Citation
Abraham, Naomi. "Comparison of Media for Intermediate-term Storage of Brewer's Yeast." Undergraduate Research Symposium, Mankato, MN, April 10, 2018.
https://cornerstone.lib.mnsu.edu/urs/2018/poster-session-A/2
