ABSTRACT:
Principal component analysis (PCA) was applied to the chromatographic and spectroscopic data of authentic Mexican tequilas (n=14) and commercially available samples purchased in Mexico and Germany (n=24). The scores scatter plot of the first two principal components (PC) of the anions chloride, nitrate, sulphate, acetate and oxalate accounting for 78% of the variability allowed a classification between tequilas bottled in Mexico and overseas, however, no discrimination between tequila categories was possible. Mexican products had a significantly (p=0.0014) lower inorganic anion concentration (range: 1.5-5.1 mg/L; mean 2.5 mg/L) than the products bottled in the importing countries (range: 3.3-62.6 mg/L; mean 26.3 mg/L). FTIR allowed a rapid screening of density and ethanol as well as the volatile compounds methanol, ethyl acetate, propanol-1, isobutanol and 2-/3-methyl-1-butanol using partial least squares regression (precisions 5.3-29.3%). Using PCA of the volatile compounds, a differentiation between tequila derived from “100% agave” (Agave tequilana Weber var. azul, Agavaceae) and tequila produced with other fermentable sugars (“mixed” tequila) was possible. The first two PCs describe 89% of the total variability of the data. Methanol and isobutanol influenced the variability in PC1, which led to discrimination.
