Determination of caramel in non-aged mixed wine spirits by synchronous fluorescence spectroscopy

Abstract

The aim of this research is to develop a fluorescence spectroscopic method for distinguishing between brandies aged in oak casks and non-aged caramel-colored mixed wine spirits, and subsequent determining of caramel in the latter. Owing to the low price of the mixed wine spirits, they are sometimes used for the counterfeiting brandies. For this reason, there is a need to establish a rapid method for estimation of drink quality to reassure consumer. The potential of synchronous fluorescence spectroscopy is demonstrated to differentiate caramel from oak wood extract, while the best discrimination is achieved using fluorescence spectra recorded at Δλ = 40 nm. For this offset value, oak wood extract shows band at 280 nm and caramel shows band at 387 nm. Based on this, caramel quantity in non-aged mixed wine spirits was calculated from fluorescence intensity at 387 nm. The calibration curve was linear over the range from 5 to 56 mg/L and the limit of determination was 5 mg/L. The relative standard deviation was <4% (within-day) and it was <6% (between-day) at 10 or 30 mg/L level.