Reducing Sugars in Wine
Method Abstract #20
Scope and Application
This method determines the quantity of reducing sugars in wine samples. This method is a variation of Rebelein’s (Gold Coast) Method.
The reducing sugar concentration is determined by adding an alkaline salt solution and copper sulfate solution to wine samples, followed by a short heating step. The samples are then quickly cooled and an excess of sulfuric acid and potassium iodide is added. The samples are then titrated with sodium thiosulfate to an inflection endpoint determined by a redox electrode. This method can be extremely time-consuming when run manually, but all sample preparation, heating, cooling and titrations can be completed automatically by the system.
Sample Titration Curve
*Data for this measuring range was obtained using laboratory prepared standards formulated from sucrose. Higher levels were obtained by using dilutions, and may be expanded further.
**The Method Detection Limit (MDL) was determined based on data obtaining a coefficient of variance better than 30%. Results may differ depending on laboratory practices and sample matrix.