Comprehensive two-dimensional gas chromatographic analysis of commercial lemon-flavored beverages

Fresh lemon juice and lemon-flavored beverages were analyzed by using comprehensive 2-D GC (GC x GC) with flame-ionization detection, with a nonpolar-polar column combination. A low-alcohol, ready-to-drink (RTD) beverage was also analyzed as fresh, and after deterioration for 12 days at 50 degrees C. Identification of some of the components in the 2-D plots was performed by comparison of peak positions of authentic standards and comparison with 1-D GC. However, without the aid of GC x GC-mass spectral data, only 24 components were identified; a large number of components remained unassigned. In some soft drinks obtained in the market, components indicative of deterioration, such as p-methylacetophenone and p-cymen-8-ol were already present in the products. In contrast, even upon heat challenge, a low-alcohol RTD beverage did not generate deterioration products of citral, such as p-methylacetophenone and the intermediates, p-menth-2-ene-1,8-diols. This was apparently related to the fact that the original formulation contained only a minute amount of the citral ingredient.