Identification and semi-quantitative determination of gum Arabic in wines by GC-MS and size exclusion chromatography.

A method for the identification and the semi-quantitative determination of the food additive gum Arabic in wines is described. Tests carried out on solutions spiked with known amounts of wine and gum Arabic polysaccharides allowed to define the suitable conditions for their quantitative precipitation and size exclusion analysis. CG-MS analyses of the different recovered fractions allowed to discriminate between gum Arabic and wine polysaccharides through the identification of glucose and mannose present only in wine polysaccharides. The proposed method was based on the wine polysaccharides free peak area obtained by size exclusion chromatography. The same cut-off time was always used both in the preparation of the calibration plot and in the analysis of the real samples. Gum Arabic was determined in a ratio of 1/10 w/w with wine polysaccharides with a detection limit of 0.074 mg ml(-1) which is lower than the lowest gum Arabic amount usually added into wines. Owing to the moderately low natural variability of the gum Arabic standards the described procedure is suitable for a semi-quantitative analysis even if its accuracy allowed a quite reliable determination of the gum Arabic amount usually added to wine.