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WineMaker News Page

Updated May 10, 2024

Vineyard Microflora Impacted by Climate; May Lead to Changing Terroir

head pruned airen vines with ripe grape clusters hanging

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?

tilted red wine glass with a glass mirror background
Photo by Charles A. Parker/Images Plus

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

a woman sorting through grape bunches during a night harvest
Photo by Wes Hagen

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

two glasses of sparkling wine sitting on an aged wooden table top
Photo courtesy of Shutterstock.com

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