| Abstract: | By experiments performed in wine‐like and must‐like model solutions, we have shown that intramolecular gluconic acid esterification leads to the formation of not only the well‐known δ‐gluconolactone (glucono‐5‐lactone) but also γ‐gluconolactone (glucono‐4‐lactone). To our knowledge, the presence of the latter is reported for the first time under conditions similar to those in grape musts and wines. Equilibrium between these lactones and gluconic acid was reached within 24 h of preparing a solution of gluconic acid, and in both wine‐like and must‐like model solutions the concentrations of γ‐ and δ‐gluconolactone represented the same proportions of the acid, ie about 60 and 40 mg g?1 gluconic acid respectively. Owing to their chemical structures, not only δ‐gluconolactone but also γ‐gluconolactone could certainly contribute to sulphur dioxide binding in musts and wines containing gluconic acid. © 2002 Society of Chemical Industry |
