This study examines the impact of adding chardonnay lees to aging Cabernet Franc wine on mouthfeel and aroma. Cabernet Franc wine was cleanly racked into 3 separate, identical barrels on December 29, 2017 so that very little lees were transferred. Then: 1) one barrel received no addition of Chardonnay lees, 2) one received 1 liter of Chardonnay lees, approximately 1.02E6 cells/mL (Low NTU), and 3) one received 3 liters of Chardonnay lees, approximately 3.06E6 cells/mL. Lees were light lees, harvested from Chardonnay wines fermented with D254. The yeast in the lees were budding under microscope, and so 90ppm of sulfur dioxide was added to the lees before adding to barrel. The wines were stirred once every two weeks until taken for sampling in late March, 2018. No major wine chemistry differences were apparent between treatments. Sulfides were all similar between wines, with some differences in Dimethyl Sulfide. Microbial cell counts were generally higher in wine with lees additions. Color intensity was slightly lower in wine with lees added. Phenolic profiles were very similar, with perhaps a slight decrease in tannin with lees addition. Overall, low lees addition had a slight tendency to increase Fruit Intensity. Lees addition in general seemed to slightly lower Astringency. However, many of these differences were weak, and differed between tastings. The lees addition wines were generally more preferred over the control wine. This suggests that lees addition to red wines can be of benefit to red wine quality. More research with more rigorous sensory analysis is needed to further clarify what aspects of wine sensory characteristics are impacted by lees addition.
This study examines the effect of barrel stirring during aging on Cabernet Franc. Cabernet Franc wine (free run and pressings) was settled for 48 hours and then racked into two identical neutral barrels. After malolactic fermentation, barrels were sulfited and one barrel was left unstirred whereas the other barrel was stirred once per week for three months. All other treatments between wines were equal. Wine chemistry was not different between treatments. The barrel stirred wine had slightly higher levels of acetic acid bacteria, some lactobacillus species, and perhaps Saccharomyces cerevisiae. O. oeni was higher in the barrel stirred treatment as well. Tannin may have been slightly lowered by barrel stirring, and catechin may have slightly increased. Overall, the wines were not found to be significantly different. Of the people who correctly distinguished the wines, there may have been a slight preference for the unstirred wine (although the tendency to have no preference was also strong). This study should be repeated again in the future, perhaps with differing levels of lees in each treatment as well and with the turbidity measured.
This study examines the impact of micro-oxygenation in aging Tannat wine. Tannat wine was split into two identical tanks. The treatment tank was micro-oxygenated with a dosing stone through a Stavin Ox Box. Due to the small volume of wine, continuous micro-oxygenation was not possible, and instead a discontinuous regimen was put in place with a target oxygen rate of 5 mL Oxygen/L wine/month. This was achieved by dosing the wine with 0.61mL Oxygen/minute for approximately 10 hours every 3-5 days. Treatment was halted when malolactic conversion began. Chemistry results were not too different, except for sulfur dioxide binding (where more sulfur dioxide was binding in the control). Sulfides were not very different, and differences in Oenococcus are likely not due to the treatment. Color was not very different. The micro-ox wine had higher levels of anthocyanins, but slightly lower polymeric pigment and tannin. For the triangle test, of 27 people who answered, 5 people chose the correct wine (19%), suggesting that these wines were not significantly different. In fact, this suggests that judges consistently and significantly did not choose the correct wine and were biased to the replicates (p<0.05). In general, of people who answered correctly, 3 preferred the micro-ox wine, and 2 preferred the control wine. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There may have been a slight tendency for the micro-ox wine to have higher Astringency, but this was very weak. These kinds of studies should be repeated in the future, over multiple varieties, utilizing both continuous and discontinuous micro-oxygenation schemes. Furthermore, more intensive micro-oxygenation regimens should be performed in future studies.
This study examines the effect of oxygenation on wines. Cabernet Sauvignon grapes were harvested and, after completion of fermentation, wine was drained and pressed into two tanks. One tank was a control, and one tank received 40 mL Oxygen/L wine/month for 3 days, and this rate was then halved every 3 days until after malolactic conversion began, where it received micro-oxygenation at 0.5 mL Oxygen/L wine/month. A third set of grapes from the same block were picked 5 days later (after a large rain event), and then received flash détente. Since malolactic conversion completed so quickly for this treatment, its oxygenation could only be at 40mL Oxygen/L wine/month for three days after draining and pressing before switching to 0.5 mL Oxygen/L wine/month. The treatments between the control and oxygenated wines were similar, but the vinification of the flashed wine was different, marked by 10 days of fermentation (compared to 14 days for the other treatments, including a 3 day cold soak). The flashed wine also had slightly different additions made. No major differences are found in wine chemistry between the control and oxygenation treatment, except for slightly higher lactic acid in the treatment. The flashed wine had higher acidity, possibly due to differential tartrate adds. The oxygenated wine had higher rates of S. cerevisiae and several Lactobacillus species relative to the control, but lower acetic acid bacteria. The flashed wine had much lower levels of acetic acid bacteria and Lactobacillus, and lower levels of S. cerevisiae as well. However, it was higher in O. oeni. Color intensity lowered among the wines from November to April; however, the oxygenated wine may have had a slight increase in color intensity relative to the control over this time (although this was weak). The oxygenated treatment had higher color intensity than the control, and the flashed wine was highest. Phenolic parameters generally decreased from November to April, and oxygenation did not appear to have much effect on the phenolic parameters. The flashed wine was much higher in catechin and quercetin and was also higher in tannin. Although it was initially lower in anthocyanin (and higher in polymeric pigment), it ended up being higher in anthocyanin.
For the triangle test, of 26 people who answered, 12 people chose the correct wine (46%), suggesting that the wines were not significantly different. In general, people who answered correctly tended to prefer the oxygenated wine, although the preference trends were somewhat complex. For the descriptive analysis, there was a strong trend for the flashed wine to have higher overall aromatic intensity than the other wines (LSD=0.97). There was a slight trend for this wine to have higher Fruit Intensity and Body, and perhaps slightly lower Herbaceous/Green character (although it was similar to the oxygenated wine in this regard). The control wine tended to have higher Herbaceous/Green character, lower Overall Aromatic Intensity, and higher Astringency (although equal to Flash in this regard). The oxygenated treatment tended to have lower Bitterness and Astringency, and perhaps lower Body as well. More studies should be performed on oxygenation, with regard to timing, amount, and with regard to continuous vs discontinuous oxygenation.
This study examines the impact of racking and returning during aging on red wine quality. Petit Verdot wine was split into two identical barrels. Once malolactic conversion was completed, one barrel was racked into tank, the barrel was pressure washed and ozonated, and then the wine was returned to the barrel and topped. The other barrel had no treatment. All other treatments between wines were identical. No major chemical differences were apparent between treatments. VA was slightly lower in the racked wine. Some sulfide parameters were lower in the racked wine, although whether these differences would impact flavor is hard to say. For the triangle test, of 20 people who answered, 7 people chose the correct wine (35%), suggesting that these wines were not significantly different. In general, of those who correctly identified the wines, 2 had no preference, 2 preferred the control, and 3 preferred the rack and returned wine. For the descriptive analysis, there were no trends for the descriptors used in this study. Judges commented that these wines were very extracted, which may have masked differences between wines. In the future, this study should be repeated on less intense grape varieties. Furthermore, the wine should be allowed to age more in future studies.
This study examines impact of stirring the lees of barrel aging red wines. Cabernet Franc wine was settled overnight in tank after pressing and then racked into two identical neutral barrels. Barrel stirring occurred once malolactic fermentation completed and continued once every two weeks until wine was sampled in late April. No major differences were found in wine chemistry. Some lactic acid bacteria counts were higher, and Brettanomyces and Saccharomyces was higher in the stirred wines as well. No differences were apparent in phenolics, except for an increase in tannin in the stirred wine. For the triangle test, of 21 people who answered, 7 people chose the correct wine (33%), suggesting that the wines were not significantly different. In general, of those who correctly distinguished the wines, 3 had no preference, 2 preferred the stirred wine, and 1 preferred the no stirring wine. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There was a very slight trend for the stirred wine to have lower Astringency. In the future, more studies should be performed with red wine lees stirring, perhaps with differing levels of lees in the wines as well.
This study examines the impact of aging in new Hungarian oak barrels vs aging in flex tank with Hungarian oak Fans on the chemical and sensory profiles of Chambourcin. Chambourcin wine was split into these vessels with the corresponding treatment. Due to the differences between aging in barrel and flex tank, the wine in flex tank required higher additions of sulfur dioxide. Not many phenolic or chemical differences exist between wines, except the wine aged in flex tank showed higher levels of anythocyanins. Judges found the wines were found to be significantly different (p<0.05), but there were no major preferences for one treatment over the other. There was a slight trend for the flex tank wine to show more Oak Character and less Fruit Intensity. Overall, flex tanks show promise in wine aging, but more work needs to be done to address oxygen ingress and headspace issues, as well as fine-tuning the use of oak adjuncts.
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.