How YAN and Gluconic Acid Testing Helps Winemakers Manage Fermentation Risk in Extreme Vintages

Extreme weather conditions are making alcoholic fermentation harder to predict. Hot and dry vintages can lead to musts with low yeast assimilable nitrogen (YAN), increasing the risk of sluggish or stuck fermentations. Cool and rainy vintages, on the other hand, can favor Botrytis development and higher gluconic acid levels, creating additional challenges for must protection and fermentation management.

For this reason, YAN and gluconic acid should not be considered secondary analyses. Together with sugar, pH, total acidity and acetic acid, they provide winemakers with practical information to make faster and more targeted decisions during harvest and fermentation.

In hot and dry vintages, grapes may reach technological maturity under stressful conditions. As a result, the must can show low levels of yeast assimilable nitrogen, reducing the availability of nutrients required by yeasts during alcoholic fermentation.

Measuring YAN before or at the beginning of fermentation allows the winemaker to plan yeast nutrition more accurately and reduce the risk of sluggish or stuck fermentations.

In cool and rainy vintages, the risk of Botrytis cinerea infection increases significantly. Grapes affected by Botrytis can contain higher concentrations of gluconic acid, a compound produced through the oxidation of glucose by the fungus.

Monitoring gluconic acid helps the winemaker assess the sanitary condition of the grapes and anticipate potential fermentation problems. It can also support decisions related to must protection, since Botrytis-affected grapes may contain compounds that bind sulfur dioxide and reduce its protective effectiveness.

In extreme vintages, rapid analytical control can make the difference between reactive correction and preventive management.

With CDR WineLab®, winemakers can determine YAN and gluconic acid in just a few minutes, directly in the winery. This makes it possible to evaluate must quality, plan yeast nutrition and define the most appropriate protection strategy before fermentation problems occur.

YAN and gluconic acid analysis therefore becomes a practical decision-making tool for managing alcoholic fermentation in the era of climate change.