Over the past two decades, wine’s ethanol content has been on the rise in most wine-producing regions. In just three decades since 1990, average alcohol levels gradually increased by about 1% ABV across some of the world’s best-known fine wine regions such as California and Bordeaux.
This shift can be attributed to the association of wine quality with grapes that have achieved complete phenolic ripeness, potentially resulting in a greater alcohol content, and to the warming climate, which leads grapes to develop increasingly higher amounts of fermentable sugars. This trend has raised concerns, including worries about its potential impact on the distinct characteristics of certain wine styles, consumer well-being, and market demand too. Studies show that younger Americans display a tendency to reduce their alcohol intake, and might therefore choose a lower-ABV option over a higher-strength one.
Producers have adopted a variety of approaches to tackle the challenge, however, many come with drawbacks, whether practical, related to taste, or to consumer expectations. A common viticultural solution consists of harvesting the grapes before they have a chance to accumulate excessive amounts of sugar, but this can affect the quality of the wine. Reducing alcohol levels through enological strategies, such as vacuum boiling and membrane filtration, present even more intricate challenges, often washing away fruit, tannin, and flavor at the same time.
The industry has instead turned its attention towards an alternative solution: the use of low-alcohol yield yeasts. “In our hot Southern California climate, high brix levels and the resulting potential high alcohol levels have been an ongoing concern for winemakers,” says Kristina Filippi, the winemaker at Wilson Creek Winery in Temecula, California, who has recently begun experimenting with alternative yeast types and strains beyond Saccharomyces cerevisiae. “My purpose in lowering starting brix is related to creating a balanced wine … a delicate dance between alcohol, acidity, body, tannin, and residual sugar. If one of those components is much higher than the others, a wine can come across as disjointed and unpleasant.” This approach offers numerous advantages: it tends to be cost-effective and straightforward to adopt for producers and, crucially, can potentially benefit wine’s organoleptic qualities, too.
Searching for non-saccharomyces yeasts
The metabolism of Saccharomyces cerevisiae yeasts, whose effectiveness and suitability in wine fermentations are well-established, consists in the transformation of sugars into alcohol. To naturally limit the production of alcohol, researchers have therefore been looking at non-Saccharomyces strains, some of which might be capable of fermenting must to complete dryness and generating appealing flavors while also producing lower levels of ethanol.
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