Wine Fraud: How Do Isotope Analyzes Work?

The world of Valais wine is once again in turmoil. The Château Constellation cellar, close to the winemaker Dominique Giroud who has hit the headlines several times, is the subject of a criminal complaint, filed by the Swiss Wine Trade Control (CSCV). The Sedun winery is suspected of having tried to sell 32,000 liters of foreign wine under the AOC Valais appellation, revealed Morning Sunday. Another procedure targeting Dominique Giroud, who benefits from the presumption of innocence, is still open before the Public Prosecutor. It also concerns the possible sale of foreign wines under the AOC Valais. For these two cases, the clues to potential fraud come from isotopic analyzes of the nectars, whose values ​​clash and seem to indicate that the grapes could not have come from Valais. But what is an isotopic analysis?