Updated November 8, 2024
A Fix for Smoke Taint?
Winemakers have become very familiar with the risks of smoke-tainted grapes caused by wildfires in recent years. Entire vintages in some areas have been lost due to smoky aromas and flavors on grapes that transfer to the resulting wine. However, a breakthrough has been reported by Australian researchers who have demonstrated the ability to lessen the perceptions of smoke taint in a wine by targeting and removing the volatile compounds absorbed by grapes during wildfires.
Previous research has looked to remove these volatile compounds with a variety of absorbents; however, the approach has largely proved unsuccessful because, in addition to removing the targeted compounds, they also removed much of the desirable compounds that contribute to a wine’s color, aroma, and flavor. This led a team of researchers from the University of Adelaide to look to selectively remove the unwanted compounds through molecularly imprinted polymers (MIPs) — which are synthetic materials that bind to targeted compounds. These MIPs were added in different ways — both during and after fermentation, contained in muslin bags or floating freely — and experiments were also done to regenerate the MIPs by rinsing them off and reusing. Using both chemical analysis and tasting panels, the trials proved beneficial.
In a paper published by the American Chemical Society, the researchers concluded the most effective use of the MIPs was with additions post-fermentation and that regenerating the MIPs enhanced removal of smoke volatile compounds. There was still some removal of desirable compounds, though the overall impression was that the method does successfully reduce the perception of smoke taint and increase palatability of wine made from tainted grapes. Read more at: www.pubs.acs.org/doi/10.1021/acs.jafc.4c03912
Historic Wine News
Scientists have recently uncovered some pieces of wine-related history that continue to better our understanding of ancient wine and grapes. First up — researchers recently concluded liquid preserved in a Roman tomb in Carmona, Spain, is in fact the world’s oldest wine from a vintage dating some 2,000 years back. Inside the tomb discovered in 2019 were a male’s skeletal remains immersed in a glass urn with liquid. The liquid had been preserved since the first century AD and taken on a reddish hue. Scientists at the University of Cordoba identified the liquid contents to be white wine, making it about 400 years older than the previous record-holder of oldest wine found in Speyer, Germany, in 1967. To determine the liquid was wine, the researchers ran a series of chemical analyses. The key to determining the substance hinged on polyphenols, biomarkers present in all wines. The results were published in the Journal of Archaeological Science: Reports. Learn more at: www.uco.es/investigacion/ucci/es/noticias-ingles/item/4717-the-world-s-oldest-wine-discovered
Though this isn’t the only history in the wine world that was recently published. The next tidbit dates back much, much longer. A team of researchers recently discovered fossilized grape seeds that range from 60 to 19 million years old in Colombia, Panama, and Peru. These are the oldest examples of grapes in the Western Hemisphere, and just a few million years younger than the earliest known grape seed fossils found in India after 66 million years. The older grapes are believed to be from around the time an asteroid hit the Earth, triggering a massive extinction of dinosaurs. The extinction of dinosaurs, scientists hypothesize, contributed to the spread of grapes around the world and there is now a better understanding of the possible time frame it took grapes to spread worldwide. Because soft tissues like fruits are rarely preserved as fossils, scientists often learn about fruits through their seeds, which more often fossilize. Learn more about the discovery at: www.fieldmuseum.org/about/press/sixty-million-year-old-grape-seeds-reveal-how-the-death-of-the-dinosaurs
Vineyard Microflora Impacted by Climate; May Lead to Changing Terroir
Like all agricultural products, weather plays a huge role in the quality and quantity of winegrapes grown any given year. With that in mind, the first thought about how climate change may impact the future of wine goes straight to the vines themselves. However, a new study shows vine health, grape sugar levels, and phenolic ripeness aren’t the only things the wine industry needs to worry about as extreme or shifting weather conditions present themselves. The microflora of vineyards will also change along with the weather. This means the terroir of wine regions across the world known for wild or spontaneous fermentations will likely change along with the weather.
A group of researchers analyzed the microbial composition across two vintages at a New Zealand winery (2018 and 2021) using a “metabarcoding approach” to assess the possible impact of climatic variation on microbial community composition in organic winemaking. Microbial dynamics were monitored over four fermentation time points and correlated with contemporaneous climate data. The results showed a significant variation in both the bacteria, fungi, and yeast species present between the two vintages. Temperature, humidity, and rainfall are believed to be the leading factors causing this difference. Much more still needs to be learned, but as the climate changes it’s reasonable to believe the organisms present in vineyards that impact the resulting wines’ character will change along with it. Of course, winemakers who rely on cultured yeast for fermentation will not feel the same impact from a changing microflora in a vineyard. Learn more about this study published earlier this year at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0296859
California Seeing a Surplus of Grapes
The California Department of Food and Agriculture Preliminary Grape Crush Report was released in February. The report paints a picture of surplus as it details the tons crushed and prices of wine grapes sold during the 2023 harvest. A total of 3.6 million tons of grapes were crushed in California, according to the report, with Chardonnay overtaking Cabernet Sauvignon as the state’s most popular wine grape. A number of acres of grapes that went unharvested would have made the total tons crushed even larger had it not been for disease and a lack of demand forcing some growers to leave grapes on the vines. “Despite the size of the overall crop, most wineries found themselves with an excess supply amid challenging conditions in consumer sales,” the report states.
Just over 650,000 tons of Chardonnay grapes were crushed in 2023 — up 25% from 2022. The total narrowly topped Cabernet Sauvignon by just 5,000 tons, which was also up 15% from 2022. The next leading grapes were Zinfandel (288,000), Pinot Noir (286,000), and Pinot Grigio (234,000).
By region, the North Coast saw the largest increase in tons crushed, up 28%, while the Southern Interior — which is still the largest wine-producing region — actually saw a 4% decrease.
Read the preliminary report at www.nass.usda.gov/Statistics_by_State/California/Publications/Specialty_and_Other_Releases/Grapes/Crush/Reports/index.php
Red Wine Headaches — Finally Some Answers?
Most folks in the wine community have heard of a friend, colleague, family member, or acquaintance complaining about a searing headache after drinking red wine, even after as little as a half glass. Many in society like to blame sulfites as the cause. But this myth was disproven many moons ago. Histamines were the next compound to be singled out . . . after all, they do cause allergic reactions. But a new suspect has risen to the top of the list . . . an antioxidant known as quercetin.
In a new study put out by a group of scientists at UC-Davis, they surmise that quercetin, a flavanol compound, in the state found in red wine can inhibit a key enzyme that breaks down alcohol. This minor disruption has a cascading effect, with one of them being elevated levels of acetaldehyde. Side effects of increased acetaldehyde in the body are well known to those who have experienced such a reaction: Flushed skin, nausea, and subsequently a headache in susceptible people. This is just a hypothesis and testing in humans has yet to occur. www.nature.com/articles/s41598-023-46203-y
Bordeaux Winemakers Push Harvest to the Nighttime
While night harvests may be a common practice in many warmer climates such as California and Australia, it’s making strides into more traditional, Old World wine regions such as Bordeaux, France. The warmer climate is pushing acid levels lower in grapes and forces viticulturalists to harvest grapes earlier and earlier, during warmer harvest dates. The push towards nighttime harvests allows time for the grapes to cool off some from the daytime heat and acid levels to creep back up. This also means less dry ice and refrigeration requirements for the incoming grapes. This has already become standard practice for the white and rosé wines in the region and is finding its way into the red grape harvest as well. phys.org/news/2023-09-climate-bordeaux-winemakers-harvest-night.html
Traditional and Charmat Methods Produce the Same Wine
For sparkling winemakers there has long been an argument of what method produces superior wines; with traditional sparkling winemakers often trying to hold the upper hand over the charmat method. New findings concluded that neither produce a superior wine. It boils down to an age-old argument that bulk production sparkling is inferior in quality to small-bottle, traditional ways.
A new study out of the University of Rio Grande in Brazil pitted the two techniques in a head-to-head competition for dominance in terms of quality. Both were aged on lees and produced a product that displayed the same qualities and aging potential. To a small degree it confirms that aging volume doesn’t denote quality of finished wine. The study did find through physico-chemical tests that the levels of diethyl succinate (fresh apple aroma) were higher in the traditional method, but it was not distinguishable enough to cause a discrepancy in sensory tests . . . and that level did diminish in time. https://oeno-one.eu/article/view/7313
Wild fermentations can often bring a level of complexity to a wine not always found using commercial Saccharomyces strains. But the tradeoff for that complexity is higher risk. What if you could introduce the good microbes of a wild fermentation to your wine without the risk? There are techniques, along with new isolated non-Saccharomyces yeasts, that can do just that.
A winemaker has saved up a bunch of commercial screw-cap bottles and wants to know what cork size fits best in that style of bottle. Learn why it is not a good idea to cork those bottles. Also get advice on aging wine temperatures and volatile acidity in blueberry wine.
