Fermenting in T bins is a common practice in Virginia but may impact wine quality in ways different from fermenting in stainless steel tanks. Thus, investigating the use of these vessels is important for the Virginia wine industry. This study compares fermenting Merlot grapes in T Bins or in Stainless Steel Tanks. Merlot grapes were harvested from the same block and chilled overnight in a refrigerated truck. Grapes were then destemmed but not crushed into a 0.75 ton T Bin as well as a 3 ton stainless steel tank. Fermentations were punched down twice daily throughout fermentation and pressed off after 19 total days. Wine was settled in tank after pressing for 5 days before barreling. All other treatments between wines were identical. The area:height ratio of the tank and the T Bin are approximately 1.340m2/m and 1.355m2/m, respectively. Thus, differences seen are likely not due to dimensions. The T Bin fermentation reached higher fermentation temperatures and exhibited a slightly faster fermentation. The T Bin fermentation resulted in decreased alcohol and increased TA. The T bin had higher tartaric acid, lactic acid, and succinic acid. Color intensity and many phenolic parameters were decreased in the T Bin wine as well. For the triangle test, of 27 people who answered, 15 people chose the correct wine (56%), suggesting a statistically significant difference between wines (p<0.01). These wines were voted to have an average degree difference of 4.6 (out of 10), suggesting that the wines were moderately different. In general, people who answered correctly preferred the tank fermentation the most. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There was a slight tendency for the T Bin wine to have higher Fruit Intensity and Herbaceous/Green character, and lower Bitterness, Astringency, and perhaps lower Body. Judges remarked that there may have been a strange aroma in the T Bin wine, ranging from sulfuric to volatile acidity to ethyl acetate. This may have impacted the perception of Fruit Intensity in this wine. From the chemistry, it is not clear what may be causing this aroma. These differences are hypothesized to be caused by differences in temperature and oxygen exposure between treatments, although not enough data is available to confirm or deny this. In the future this study should be repeated multiple times to gain more information and should be analyzed in more detail.
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 the impact of saignee on Merlot wine quality. Merlot grapes were harvested from the same block on the same day and was split into 4 T Bins. The T Bins received the following treatments: 1) 0% Saignee, 2) 7% Saignee, 3) 15% Saignee, and 4) 25% Saignee. All other treatments between wines were identical. Brix and pH slightly increased by saignee, and TA slightly decreased in the must. Wine chemistry was not much affected by saignee. Color intensity increased with increasing saignee. Anthocyanin and tannin were also increased by saignee. These increases were generally correlated to increasing levels of saignee. Overall, the higher rates of saignee may have slightly increased Fruit Intensity, Herbaceous/Green character, Bitterness, and Astringency. The higher rates of saignee tended to be more preferred (although preferences changed between tastings). Saignee may prove to be a valuable tool in Virginia red winemaking and should be examined at many different sites among many different varieties.
This study examines the effect of different rates of macro-oxygenation on the phenolic and sensory qualities of Cabernet Franc. Grapes were harvested on the same day but kept separate, and all treatments between lots were kept the same except that one T Bin received no macro-oxygenation, one T Bin received a rapid macro-oxygenation to attain 5mg/L added oxygen after punchdowns (<1 hour aeration), and another T Bin received a slow aeration to attain 5mg/L added oxygen after punchdowns (3-4 hours aeration). Oxygen was added after punchdowns. No major chemical or phenolic differences are noticeable between treatments, except that phenolics slightly decreased in aerated wines. Macro-oxygenation tended to lower Overall Aromatic Intensity, with rapid macro-oxygenation tending to lower it the most. There were slight tendencies for macro-oxygenation to increase oxidation qualities and lower Fruit Intensity, and rapid macro-oxygenation tended to have slightly higher Bitterness/Astringency. These tendencies, however, were very weak. In general, people tended to prefer wine made without macro-oxygenation, and least preferred the wine made with rapid macro-oxygenation. Because these trends were very weak, this study should be repeated a few more times before making strong conclusions about macro-oxygenation.
Reverse Osmosis was performed on Merlot, Malbec, and Petit Verdot wine in order to assess its effect on the chemical and sensory aspects of these wines. Chemical parameters were not much affected by reverse osmosis, although color intensity was increased in RO wines. Hue was also slightly increased, suggesting some oxidation from RO. The Merlot and Malbec wines were found to be significantly different between treatments through triangle testing, but Petit Verdot showed no discernable difference.
Petit Verdot wine was processed into open top barrels or T-bins in order to compare the effect of fermentation vessel on the chemical and sensory attributes of the wine. The wine fermented in T-bin had slightly higher volatile acidity, pH and ethanol. Sensory results were not significant between wines.