Chemometric validation of an enzymatic method to detect glucose and fructose in wines

Fermentable sugars influence the alcohol content of the wine, as well as the wine's mouthfeel attributes (such as astringency, viscosity, and density) and overall texture, reduce the perception of astringency (by interacting with polyphenols), help retain aromatic compounds in the wine, and enhance its colloidal stability. Measuring fermentable sugars is essential for oenologists to decide the best harvest time and manage fermentation. Traditional titrimetric methods, like the Lane–Eynon method recognized by AOAC, require skilled personnel, lengthy analysis, careful monitoring, and hazardous reagents. The International Organisation of Vine and Wine recommends using simpler spectroscopic methods for measuring sugar levels in wines, though accuracy depends on analyst expertise. This research aimed to validate an automated enzymatic system for quantifying glucose and fructose in wine samples. Such technology can reduce costs by minimizing the need for specialized staff and increasing daily analysis throughput, while also lowering operator error and improving environmental sustainability through better solvent use. The validation process was performed on various wine types (dry red, dry white, moderately sweet, and sweet) by comparing results from the OIV-MA-AS311-02 method by a trained operator (reference method) to those from the automated system. Despite notable average discrepancies, the automated method was found suitable for its purpose, as the differences were less than the measurement uncertainty at similar concentrations, and its repeatability exceeded that of the reference method.