415-978-3506 (S.F. Press Center, Aug. 9-13)
Katie Cottingham, Ph.D.
415-978-3506 (S.F. Press Center, Aug. 9-13)
American Chemical Society
San Francisco, Aug. 10, 2014 — Location. Location. Location. The popular real estate mantra also turns out to be equally important for growing wine grapes in fields and storing bottles of the beverage at home or in restaurants, according to researchers.
Those are just two of the topics that will be covered in a symposium titled, "Advances in Wine Research," that will run today through Tuesday at the 248th National Meeting & Exposition of the American Chemical Society (ACS). The meeting features nearly 12,000 reports. A brand-new ACS video on the topics is available at https://www.youtube.com/watch?v=Km3UujrPLEU.
"In this symposium, we will be evaluating components that affect flavor, taste, mouthfeel and also color, as well as sustainable vineyard and winemaking variables that impact the composition of the wine," says symposium organizer Susan E. Ebeler, Ph.D. "The San Francisco location is ideal for this symposium, being located near the heart of the U.S. wine-growing region of Napa Valley. The symposium is expected to draw a high level of interest from local wineries, food industries and government agencies."
One study being presented during the symposium, of which Ebeler is a co-author, finds that it really does matter where the same grapes are grown when it comes to taste and aroma.
The Argentinean Malbecs tended to have more ripe fruit characteristics, sweetness and higher alcohol levels, while those from California were more bitter, and had more artificial fruit and citrus aromas, Ebeler says.
Overall, the study covered the chemical and sensory effects of different regions using 41 research lots of Californian and Argentinean Malbec wines. In addition to having trained panelists evaluate the wines, the team conducted a gas chromatographic analysis of the wine volatiles — mostly those compounds that would be smelled when sniffing the beverage.
Another study in the symposium found dramatic differences in the aging of wine depending on where the bottles were stored. This team placed 400 bottles from 20 different lots of Sangiovese wine for 24 months either in a professional wine cellar with strictly controlled temperature (59-62 degrees Fahrenheit) or in conditions mimicking a dark room in a home (68-80 degrees Fahrenheit) for different seasons.
"We discovered that a relatively small difference in the temperature speeds up several chemical reactions associated with wine aging and even promotes new reactions that are not observed at lower temperatures," says study leader Fulvio Mattivi, who is a researcher at Fondazione Edmund Mach, Research and Innovation Centre, San Michele all'Adige, Italy. "After six months under domestic conditions, the wine in the bottle was approximately as 'old' as a bottle from the same producer and lot stored for two years under cellar conditions. The house-stored wine was aging approximately four times faster!"
When tested, the wine stored in the dark room had fewer healthful antioxidants and less red pigmentation than the cellar versions, making it less flavorful, he reported.
Other topics that will be addressed in the symposium are:
A press conference on this topic will be held Tuesday, August 12, at 3 p.m. Pacific time in the Moscone Center, North Building. Reporters may report to Room 113 in person, or access live video of the event and ask questions at the ACS Ustream channel
Mattivi's funding was provided by the Italian Ministry of Agricultural, Food and Forestry Policies, under the project Functional Food Quality.
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Susan Ebeler, Ph.D.:
Effect of region on the volatile composition and sensory profiles of Malbec and Cabernet sauvignon wines
Regionality, frequently called terroir, is often used as a way to market wines from different locations. However, a great deal of the information on regionality is from the popular press with only a few scientific publications on varieties such as Pinot noir and Riesling. In this presentation we will discuss the chemical and sensory effects of regionality using 30 commercially made Australian Cabernet sauvignon wines as well as 41 research lots of Californian and Argentinean Malbec wines. For the Malbec wines the Argentinean wines tended to have more ripe fruit characteristics, sweetness and higher alcohol levels while the wines from California had more bitter tastes, more artificial fruit and citrus aromas. There were also clear volatile chemical differences among the regions for 48 of the 60 measured compounds using a semi quantitative, automated headspace solid phase micro extraction (HS-SPME) gas chromatography-mass spectrometry (GC–MS) method combined with synchronous Selected Ion Monitoring (SIM). For the Australian Cabernet sauvignon wines we also found that some of the 10 different wine regions (called Geographical Indications or GIs) could be separated based on their sensory attributes. A HS-SPME comprehensive GC-time of flight mass spectrometry (GCxGC-TOFMS) method showed that a number of the over 350 identified compounds were unique for particular GIs and groups of GIs that were close to one another geographically. These studies showed that for both very well controlled research fermentations and for less controlled commercial fermentations it is possible to determine sensory and chemical regional differences for wines.
Influence of storage conditions on the composition of red wines
The knowledge of the influence of the temperature on the chemical composition of red wines may be useful, given that unappropriate storage is likely to shorten the shelf life while decreasing the wine quality. The putative markers of ageing of red wines stored for two years with two different storage temperatures (cellar vs. domestic) were investigated via MS-based untargeted metabolomics, and further confirmed by additional metabolite profiling .
Among the 10k features extracted from the metabolomic data set, the significant ones capable of distinguishing between the two storage conditions were mostly pigments and other phenolics, several of which were annotated with 1stlevel identification. Tentative identification of the remaining chromatographic peaks, without a standard, was made by using spectral features, literature information about chromatographic properties and mass spectra records from databases (HMDB, Kegg or MassBank) and an internal database for the wine metabolome based on the bibliography.
The results of multivariate analysis clearly showed that wines stored in the cellar changed little even after two years of storage, while wines stored in typical domestic conditions developed approximately four times faster. Ageing in domestic conditions appeared to induce an accelerated decrease in native anthocyanins, while specifically promoting the formation of pinotin A-like pigments. Interestingly, we observed a temperature-dependent pathway involving the addition of bisulfite to the flavanols and leading to the formation of several catechins and proanthocyanidins sulfones, along with hydrolysis reactions involving various phenolics, which could cause some concern about wine stability especially in the case of quercetin.
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