Fermenting Merlot in T Bins vs Tanks (2017)

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.

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