Levulia Alcomeno Yeast Trial (AEB) (2017)

This study examines the impact of Levulia Alcomeno yeast (AEB) on Cabernet Franc wine quality. Levulia Alcomeno is a non-Saccharomyces yeast strain (K. thermotolerans) which can promote acid formation and decrease acidity during early stages of fermentation. Cabernet Franc grapes were divided into two T Bins, one of which received Levulia Alcomeno and the other did not. Both T Bins underwent a 7 day cold soak. Afterwards, the control was inoculated with FX-10, and both T Bins were fermented identically. Roughly halfway through fermentation, the Levulia treatment received FX-10 as well in order to ensure complete fermentation. All other treatments between wines were identical. Chemistry was not altered during cold soak. Fermentation kinetics were very similar between treatments. Levulia Alcomeno wine saw increased TA, lactic acid, and volatile acidity. However, this wine also had higher pH. The Levulia Alcomeno wine had higher levels of ethyl acetate and isobutanol, and slightly lower levels of amyl alcohol and isoamyl alcohol. Color was not very different between treatments. The wines were not determined to be significantly different via triangle testing. Of those who answered the triangle test correctly, they preferred the control wine, and there may have been a nondescript off flavor in the Levulia wine. For the descriptive analysis, there were no strong trends for the descriptors used in this study. The descriptive data suggests that there may have been some glass-to-glass variation, possibly due to biases from tasting order. Drawing sensory results is thus difficult. Levulia Alcomeno is recommended to be used in conjunction with Fermol yeasts, which may have impacted results. In the future, more studies should be performed on this yeast in conjunction with AEB Fermol yeasts.

Read Full Report (PDF)

Yeast Strain Selection to Produce Sulfur Dioxide-Free Merlot Wine (2017)

This study examines the efficacy of non-Saccharomyces yeast selection to produce wines without the use of sulfur dioxide. Merlot grapes were harvested on September 28 and stored overnight at 45°F. The next day fruit was destemmed, sorted, and crushed into two separate bins (0.5 tons per treatment). One bin received 6g/hL sulfur dioxide (control), and the other received 5g/hL Primaflora VR Bio (AEB) as a sulfur dioxide replacement (no sulfur dioxide treatment). Both bins received a two day cold soak (one punchdown per day, with dry ice additions), and then the control bin received 15g/hL FX10, and the treatment received 15g/hL FX10. At this point the bins were moved out of the cold room in order to warm up. Punchdowns were twice per day until fermentation became vigorous (October 6), which then received 3 punchdowns per day. Fermentation lasted for 8 days, after which the wine was drained off the skins and put into stainless steel tanks for aging (only free run was used). On November 30, wines were filtered with K250/EK filters and sterile filtered (0.45 micron) and bottled on December 7. At bottling, the control received 1g/hL sulfur dioxide. The wine without sulfur dioxide had slightly less alcohol and lactic acid, and slightly increased volatile acidity. It also had less color and had a slightly longer lag phase in fermentation. The no sulfur dioxide wine seemed to have more yeasts throughout its life except for Hanseniaspora, relative to the control. Both fermentations had similar bacterial counts. Overall, judges were more or less able to correctly distinguish the wines made with and without sulfur dioxide, although in one tasting this was statistically significant and at the other it was not. Judges tended to prefer the wine made without sulfur dioxide. The no sulfur wine may have had higher Fruit Intensity, higher Overall Aromatic Intensity, and higher perceived Acidity relative to the wine made with sulfur dioxide.

Read Full Report (PDF)

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.

Read Full Report (PDF)

Effects of Adding Hydrolyzable vs Condensed Tannin during Red Wine Fermentation (2016)

This study examines the impact of adding different sources of exogenous tannin to fermenters during Merlot processing. The treatments were set up as follows: 1) Control, 2) FT Rouge (ScottLabs) at 30g/hL, 3) FT Rouge (ScottLabs) at 50g/hL, 4) Tanéthyl Effe (AEB) at 10g/hL, and 5) Oenotan Selection (Esvin) at 10g/hL. All treatments were the same, except that the treatment with FT Rouge at 50g/hL was inoculated with a different yeast from the rest. This wine was therefore not tasted at sensory sessions. No major wine differences could be seen between treatments. The tannin varied with their effect on color intensity: some increased intensity slightly whereas others slightly decreased it. Anthocyanin, in general, was slightly lowered by tannin addition. Tannin content was relatively unaffected, except for FT Rouge 50, which experienced a large increase in tannin. The differences from FT Rouge 50, however, may have been due to the yeast strain used, and does not indicate necessarily that the increase in tannin addition had the effects. Overall, no major preferences could be seen for any treatment, except that the Tan Ethyl Effe was often least preferred. There may have been large changes in wine sensory qualities in bottle over time, as the wines seemed to taste different at the different tastings. This could confound any attempt to compare wines across tastings. This study suggests that exogenous tannin can have impacts on final wine chemistry and sensory qualities, and this may be largely impacted by yeast strain selection as well. In the future, more studies examining the combined impact of exogenous tannin addition with yeast strain selection should be performed.

Read Full Report (PDF)

The Effect of Different Sources of Lees and Lees Products on Aging Cabernet Franc Wine (2016)

This study examines the impact of adding different sources of lees to aging Cabernet Franc wine. Cabernet Franc wine was split into 5 barrels with the following treatments: 1) no lees addition, 2) 2 pints of Chardonnay lees added, 3) 2 pints of Viognier Lees added, 4) Laffort Autolees added, and 5) AEB Batonnage Elevage added. The wines were stirred once every two weeks until taken for sampling (in February). Wine chemistry did not differ between treatments. The sulfide profile did not differ at the limit of detection of the laboratory analyses. All treatments slightly lowered color intensity and increased hue, except for the AEB Batonnage treatment, which increased color intensity and decreased hue. In the first tasting, the Control and the Laffort Autolees treatment strongly increased Fruit Intensity, but this was not replicated at the second tasting. There were weaker tendencies between tastings, however. Lees which originated from wine (Viognier and Chardonnay Lees) appeared to have a consistent impact on the aroma of the wines, whereas lees which originated from products had less impact on wine aroma. An exception would be the AEB Battonage Plus treatment, which appeared to increase Herbaceous/Green qualities. The AEB lees tended to have the largest impact on Astringency. No major preference trends could be seen. These results were very mixed, likely due in part to the complexity of the project. This project produced interesting results, and more work on the impact of lees management in red wines should be done before drawing hard conclusions about these different lees sources. Stylistic possibilities of adding aromatic white wine lees to red wine should also be considered in future studies.

Read Full Report (PDF)

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.

Read Full Report (PDF)

Yeast Nutrient Comparison in Chardonnay (2015)

The effects of the yeast nutrients Go Ferm, Fermaid O, and Fermoplus DAP Free on fermentation kinetics, wine chemistry, wine microbiology, and wine sensory attributes, were compared .  Go Ferm resulted in the most rapid fermentation.  Not much chemical differences were observed.  Most people preferred the wine made with Fermoplus DAP Free.

Read Full Report (PDF)