This past fall we took wort out to Agriberry farm in-order to collect yeast which natural occur within the local terroir. The wort was placed in 5 different locations on the farm to try and collect as many strains as possible in portable coolships. These locations were under the following species of berries and peach trees:
- Himbo Top
- Black Magic
After a day of collecting wild yeast, the wort was transferred to Cornelius Kegs and taken to Randolph-Macon College. From there, Professor Dr. Grace Fong and her student Matthew Houle started working to isolate viable yeast and bacterial strains. Samples were drawn from the Cornelius kegs and plated on universal beer agar (UBA).
There were a large number of yeast and bacteria strains collected, but the three most interesting yeast cultures found were taken to VCU for sequencing to find the exact strain of each. Two of the cultures came from the peach keg, and one came from the Himbo Top raspberry keg. They also suspected a Dekkera yeast strain, a common yeast found in Belgian lambics.
Here's a rundown of what Dr. Fong found after several weeks:
- Peach showed two genera of yeast, Hanseniaspora and Pichia.
- Himbo Top showed three genera of yeast, with Saccharomyces being the most abundant at week two.
- The specific gravity of all of the kegs decreased over two months.
- All experimental kegs contained Lactobacillus and showed a drop in pH from week 1 to month 2.
Interesting yeast found:
- Pichia (Bokulich and Bamforth, 2013). This yeast has low sugar fermentation and tropical fruit/ pineapple aroma.
- Hanseniaspora (Spitaels et al., 2014) is found in the first phase of Belgian Lambic fermentation and has low sugar fermentation.
- Saccharomyces (Spitaels et al., 2014). Found in the Second phase of Belgian Lambic spontaneous fermentation, the main fermentation phase.
After the yeast had been growing for some time, the brew crew sampled each batch of wort to identify which flavors and aromas they like for three new beers.
The work is not done! Dr. Fong will continue to research so stay tuned for more updates.