Progress 07/01/05 to 06/30/08
Outputs
OUTPUTS: One-thousand three hundred and twenty-five commercial wines made from five red Vitis vinifera cultivars, Cabernet Sauvignon, Merlot, Pinot noir, Syrah and Zinfandel and several blends were evaluated. Samples were taken from the United States (California, Oregon, Washington), Australia and France. Concentration of tannins ranged from 30 mg/L to 1895 mg/L Catechin Equivalents (CE) among all the wines measured. The mean concentration of all wines was 544 mg/L catechin equivalents (CE) with a standard deviation of 293. Within a single variety the variation in the concentration of tannins is larger than an order of magnitude, and in two varieties (Cabernet Sauvignon, Pinot noir) the variation was 32-fold. Due to the large amount of variation in the concentration range of tannins, there was overlap among the different populations. Despite the variation, differences were found (p<0.05) at the population mean value among the varietals and they are as follows: Cabernet Sauvignon (672
mg/L CE) = Zinfandel (652 mg/L CE) > Merlot (559 mg/L CE) > Syrah (455 mg/L CE) > Pinot noir (348 mg/L CE). Pinot noir and Syrah wines from different states were compared and revealed that Oregon and California Pinot noir wines were not statistically different while California Syrah was higher in tannin than both Washington state wines and those from several states in Australia. Wines from the Bordeaux region (n=55) were similar to Cabernet Sauvignon and Merlot wines which is not surprising given that those are the main blending components in Bordeaux. We collected price and case production information from 288 Washington wine samples that was available. We found an extremely poor relationship between the tannin concentration of wine and its price. We found an equally poor correlation when we evaluated single varieties. This can be explained by the distinct difference in the price of wines from different AVAs. Walla Walla and Red Mountain wine had greater costs than Columbia Valley
and Yakima Valley where costs were significantly lower than the other AVAs (p>0.05). Previously we had shown that Walla Walla and Red Mountain AVAs had low and high tannin concentrations, respectively. When we evaluated the case production of wine versus case production size for the wine we also saw an extremely poor correlation. We found that Walla Walla, Red Mountain and Yakima Valley have production have fairly modest production (71-12,950) while the wines from Columbia Valley were done on a larger scale (87-310,000). Therefore, we attempted to evaluate the relationship between case production, wine price and tannin concentration. Results show that even within an AVA that has a larger scale of production there is no relationship between wine price, scale of production and tannin concentration of wines. Results also suggest there is no consensus amongst winemakers about how much tannin should go into specifically priced types of wine. Even within a single winery a relationship did
not exist. Other factors may need to be taken into account but it seems likely that there is so much variation there is likely no variable that may account for it.
PARTICIPANTS: James F. Harbertson, Enology, Washington State University
TARGET AUDIENCES: Wineries
Impacts
The commercial wine tannin survey provided baseline numbers for which winemakers can compare their own results. The survey also showed that the tannin composition of wine is exceptionally variable and even more so than the grape tannin data that we collected. This suggests that use of winemaking techniques (such as the ones studied in our project) influence the tannin concentration of the wine more than intrinsic differences in the fruit. Much effort as gone into disseminating this data at Washington Wine and Grape meetings as well as in California and Australia.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Washington Cabernet Sauvignon wines (n=186) and Merlot wines (n=143) were analyzed for their phenolic constituents using a combined bisulfite bleaching, protein precipitation and pH shift analysis. The samples were taken from multiple vintages of wine ranging from 1990 to 2004, but the majority of the samples were taken from the 2002 and 2003 vintages. The data was compiled into a simple database and analyzed. Merlot wines were on average less tannic than the Cabernet Sauvignon averaging 596 and 698 mg/L catechin equivalents (CE), respectively. A twelve fold range of tannins was found for both cultivars studied (141-1665 mg/L CE,158-1895 mg/L CE) with the latter range being attributed to Cabernet Sauvignon. In agreement with earlier studies, our data demonstrated that the concentration of color components is time dependent. We found that wines aged more than 5 to 7 years in the bottle had converted the majority of their anthocyanins into polymeric pigments. Tannins
were the most variable phenolic group and when we compared wines made from different grape growing regions across all of the vintages, we observed some notable differences among the Cabernet Sauvignon wines. For Cabernet Sauvignon wines, Red Mountain (average=843, n=22) was noticeably more tannic than wines from Walla Walla (average 537, n=27) and Yakima Valley (average=653, n=38) while the wines from Columbia Valley were not different (average 737, n=91). The tannin content of Merlot wines was not as variable and only Red Mountain (average 829, n=13) was greater than Columbia Valley (average 582, n=69), Yakima Valley (average 560, n=29), and Walla Walla (average 547 n=22). The grape survey is summarized under project 0612
Impacts
This data shows that there are differences between cultivars. Wine made from Washington Cabernet Sauvignon is more tannic than wine made from Washington Merlot. It confirms the sentiment that on average, wines made from Red Mountain fruit are more astringent than wines made from other AVAs. It also shows there is a tremendous range of tannin in finished wines even within a single AVA and cultivar (the highest value was up to 12 times larger than the smallest value, and there was a clear overlap between different cultivars and AVAs), showing winemakers and grape growers that the qualities of the final product are not defined completely by either AVA or cultivar.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Tannins are the most abundant class of phenolics in grape berries and red wines. They contribute bitterness and stringency to red wines and are a major sensory and quality component. The major objectives of the proposed work was to conduct a survey of the phenolic components found in Merlot and Cabernet Sauvignon wines and to assemble that data into a database. The PI and his technical staff began to build a database of WA wines to establish normal values towards the major objective of the proposed work. We built a standard template for data entry that is available to interested wineries. We also built a basic Excel spreadsheet database and have begun collecting wine for analysis. This, coupled with the sensory research under other projects, should prove to be invaluable information for winemakers. The project also helped in the collection of finished wines of a cooperator and assembled the data collected in her laboratory into the database.
Impacts
The impact of the work will be baseline values for phenolic quality components in WA wine. These values will be provided to WA state vintners to make better decisions about there winemaking practices.
Publications
- No publications reported this period
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