Using Yeast to Improve Color and Aroma Extraction from Skins (in Collaboration with 2B) (2017)

This study examines the impact of Rubino Extra (2B), BM45 (ScottLabs), and Alchemy III (Anchor) on the phenolic and aroma characteristics of Cabernet Franc wines. The goal was to see if the Rubino Extra yeast could enhance anthocyanin and aroma extraction from the grapes, relative to other yeast strains. Grapes were harvested on the same day and processed into 3 separate T Bins. Each of the three T Bins were inoculated with one of the three yeasts. All other treatments between wines were identical. The BM45 trial fermented slowest, and Rubino Extra trial fermented fastest. Lactic acid was higher in the wine produced with BM45. Color intensity varied among yeasts. Anthocyanins were higher in the Alchemy 3 trial, and lower in the Rubino Extra trial. Overall, not many trends were seen between these wines. The Rubino Extra yeast tended to produce wines with slightly lower Overall Aromatic Intensity and Fruit Intensity. The Alchemy 3 and BM45 yeasts were fairly similar, except that BM45 was perhaps more in-between the Rubino Extra and the Alchemy 3 yeast. The Alchemy 3 yeast appeared to produce a distinctive floral or fruity quality. Preference trends reversed between tastings, and as such it is unclear which yeast strain was the most preferred.

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The Effect of Zymaflore Alpha Yeast (Laffort) during Cold Soak on Cabernet Franc Wine (2016)

This study examines the impact of adding Zymaflore Alpha (T. delbrueckii) (Laffort) yeast prior to a cold soak on the chemical and sensory characteristics of Cabernet Franc wine. Cabernet Franc from the same block was harvested on the same day and processed into two separate T Bins. All additions were identical, except that one T Bin received Zymaflore Alpha yeast and the other received no yeast. Both bins then underwent a 6 day cold soak at 50°F. After cold soak, both bins were inoculated with FX 10 yeast. All other treatments were identical. Wine was pressed around 3 weeks after processing. The Zymaflore treatment lowered titratable acidity and slightly lowered ethanol, but otherwise no major chemistry differences were apparent between wines. The Zymaflore treatment had increased acetaldehyde and propanol, but most other higher alcohols and fusel oils were lowered by the treatment. The Zymaflore treatment also slightly lowered color intensity. Triangle testing showed that, of 7 people who answered, 4 people chose the correct wine (57%), suggesting that the wines were not significantly different. However, the wines were almost significantly different. 3 out of 4 judges who answered correctly preferred the Zymaflore treatment to the control, and the other judge had no preference. The wine with Zymaflore was described as being slightly smoother, less harsh, or more balanced in terms of acidity. No major trends were discovered for the descriptors used in this study. There was a slight tendency for the Zymaflore wine to have lower Astringency and Overall Aromatic Intensity. The use of non-Saccharomyces yeast strains merits further work.

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Levulia Alcomeno (AEB) Yeast Trial on Cabernet Franc (2016)

This study examines the impact of Levulia Alcomeno (K. thermotolerans) yeast inoculation followed by inoculation with FX-10 after 4 days versus inoculating with FX-10 alone on Cabernet Franc wine. K. thermotolerans is a yeast species which often produces wine of higher acidity and lower ethanol. Although the Levulia Alcomeno fermentation had a longer lag phase, they both finished fermentation around the same time. Wine fermented with Levulia Alcomeno showed slightly increased TA, lactic acid, and decreased pH and ethanol, which is consistent with K. thermotolerans fermentation profiles. The decrease in pH corresponds to a 23% increase in proton concentration. Additionally, this wine showed less acetaldehyde and more isoamyl alcohol. These results suggest that Levulia Alcomeno, while potentially affecting the chemical makeup of wine, did not have a strong impact on the sensory qualities of wine. It may have slightly increased Fruit Intensity and decreased Astringency, but if so this was a weak trend. This yeast shows promise, however, and more studies are warranted to determine whether this yeast can reproducibly produce these effects, and whether these effects are enhanced based on different starting fruit chemistry. At this point, no firm conclusions can be drawn.

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H2S Production by Different Low-H2S Producing Yeast Strains (2016)

This study examines the effect of different low H2S-producing yeast strains on the sensory attributes of Cabernet Franc and Cabernet Sauvignon Rosé. The grapes were harvested on the same day, pressed together, and after settling was racked into four different 484L puncheons (2006 Hungarian oak from the same cooper). The barrels were inoculated with the following yeasts: Rhône 4600 (ScottLabs), Allegro (Phyterra), Sensy (ScottLabs), and Fermol Elegance (AEB). Rhône 4600 is not marketed as a low H2S-producing yeast strain and was intended to act as a soft control. The strains showed similar fermentation kinetics except for Rhône 4600, which was markedly slower. Additionally, the wine produced by Rhône 4600 had a higher alcohol content and higher total SO2, possibly from yeast production. The sulfide contents of the wines, however, were essentially indistinguishable. No strong trends were found with the descriptors used for this study. Rhône 4600 tended to show higher Fruit Intensity and Overall Aromatic Intensity. Many of these wines were perceived as slightly reduced. In general, people tended to prefer wines produced with Rhône 4600 and Allegro yeasts.

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ScottLabs IONYS WF Yeast Trial on Chardonnay (2016)

This study examines the impact of IONYSWF yeast (Lallemand) on Chardonnay wine when compared to fermentation with CY3079. Chardonnay juice was settled and split into separate barrels, inoculated with either CY3079 or IONYSWF. Although the IONYSWF fermentation proceeded much slower, not many chemical differences could be seen between the different yeast strains, except that the pH and TA of the IONYSWF – fermented wine was slightly higher. The lower level of free sulfur dioxide in CY3079 suggests a slightly higher production of sulfur dioxide-binding compounds. These results suggest that people are able to tell a difference between Chardonnay wine produced with IONYSWF yeast and wine produced from CY3079. People often preferred wine produced with IONYSWF yeast, likely due to its tendency to enhance Fruit Intensity, Overall Aromatic Intensity, Depth of Flavor, and Body. Although the yeast is marketed to increase acidity, this was not observed in this study. This yeast shows promise with regard to aromatic development in Chardonnay, but more studies are needed to confirm this.

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CY3079 and Vivace Yeast Trial in Chardonnay (2015)

Chardonnay wines produced with CY3079 and Vivace yeast strains were compared. Vivace yeast is marketed as a low hydrogen sulfide-producing yeast.  There were little chemical differences between the resulting wines, although significant sensory differences were discerned.  People tended to prefer the wine produced with CY3079.  No conclusions can be drawn about the efficacy of Vivace in producing low levels of hydrogen sulfide.

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Andante, D254, and IONYS WF Yeast Trial in Petit Verdot (2015)

Andante, D254, and IONYS WF yeast strains were used in the fermentation of Petit Verdot.  IONYS WF yeast seemed to increase the titratable acidity and lower the pH slightly, and also seemed to lower the overall phenolic content of the wine.  IONYS WF and D254 wines were slightly more preferred than Andante wines.

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The Use of Different Yeast Strains to Diminish Green Character in Cabernet Franc (2014)

The yeast strains Enartis ES488 and Lallemand GRE were used in order to lower green character in Cabernet Franc.  The titratable acidity between wines was fairly different, but sensory analysis did not show significant differences between the two wines.  This study does not conclusively show whether these yeasts can diminish green character.

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Sulfur Dioxide Resistant Strains of EC 1118 (2014)

EC 1118 produces high concentrations of sulfur dioxide during fermentation.  Some sulfur dioxide-resistant strains of EC 1118 have been developed in response to this tendency.  This study examines the difference in wine chemistry, fermentation kinetics, and sensory characteristics of wine produced using traditional EC 1118 and the sulfur dioxide-resistant strain of EC 1118.  The resistant strain produced less volatile acidity, but resulted in a longer fermentation.  No significant sensory differences were found between wines.

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Anchor and ScottLabs Yeast Comparison in Merlot (2014)

ScottLabs EC 1118 PDM, ScottLabs CRVP, Anchor NT50, and Anchor NT202 yeast strains were compared for their effect on pH, ethanol and volatile acidity production in 2014 Merlot.  Fermentation kinetics were also compared.  CRVP exhibited the fastest fermentation kinetics but produced the highest volatile acidity. EC 1118 PDM produced the highest ethanol and lowest volatile acidity.

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