Excitation-emission fluorescence as a tool to assess the presence of grape-must caramel in PDO wine vinegars

The Use of Fluorescence Spectrometry Combined with Statistical Tools to Determine the Botanical Origin of Honeys

At a time when the botanical origin of honey is being increasingly falsified, there is a need to find a quick, cheap and simple method of identifying its origin. Therefore, the aim of our work was to show that fluorescence spectrometry, together with statistical analysis, can be such a method. In total, 108 representative samples with 10 different botanic origins (9 unifloral and 1 multifloral), obtained in 2020-2022 from local apiaries, were analyzed. The fluorescence spectra of those samples were determined using a F-7000 Hitachi fluorescence spectrophotometer, Tokyo, Japan. It is shown that each honey variety produces a unique emission spectrum, which allows for the determination of its botanical origin. Taking into account the difficulties in analyzing these spectra, it was found that the most information regarding botanical differences and their identification is provided by synchronous cross-sections of these spectra obtained at Δλ = 100 nm. In addition, this analysis was supported by discriminant and canonical analysis, which allowed for the creation of mathematical models, allowing for the correct classification of each type of honey (except dandelion) with an accuracy of over 80%. The application of the method is universal (in accordance with the methodology described in this paper), but its use requires the creation of fluorescence spectral matrices (EEG) characteristic of a given geographical and botanical origin.

Monitoring winemaking process using tyrosine influence in the excitation-emission matrices of wine

Wine samples collected during the winemaking process have been analyzed employing a previously optimized UHPLC-FD method, determining their biogenic amines and amino acids profile. The results obtained have been submitted to a statistical analysis from which it was extracted that the most influential analyte was tyrosine. Thanks to its fluorescence, a method for its determination by excitation-emission matrices has been proposed. The accuracy of the method has been checked by means of Elliptical Joint Confidence Region test. The winemaking process has been monitored with this method, obtaining a faster and cheaper way to follow the process.

Sensory and spectroscopic characterization of Argentinean wine and balsamic vinegars: A comparative study with European vinegars

In Argentina, vinegars are cheap agro-food products without exhaustive regulation and the production of high-quality vinegars has not been exploited yet. In fact, Argentinean vinegars have not been studied. In this context, a first study of Argentinean balsamic and wine vinegars was carried out by a sensory and spectroscopic characterization and by a comparison with well-recognized European vinegars. For that, ultraviolet-visible and fluorescence spectroscopies were applied together with principal component analysis (PCA) and parallel factor analysis (PARAFAC) performed on each data set, respectively. Results showed differences between acetification processes, origin countries and a wide variability within Argentinean production. The sensory characterization on Argentinean wine vinegars was performed by triangular and ordering preference tests showing statistically significant preferences toward the traditional and the rapid vinegars. This work highlights the effect of production on quality in order to provide added value to the Argentinean vinegars.

Assessment of UV-visible spectroscopy as a useful tool for determining grape-must caramel in high-quality wine and balsamic vinegars

The addition of E-150d caramel, known as grape-must caramel in vinegars, is a legal but without limitation practice in Spanish wine vinegars, as those with a protected designation of origin (PDO), for unifying the final colour of different batches and barrels. It is also used in the production of 'Balsamic vinegar of Modena' vinegars, with a maximum addition fixed at 2% v/v by law. Although its quantification in vinegars was studied by other techniques, there is still not any official method for it. Therefore, UV-vis spectroscopy was assessed as a quick analytical method able to quantify grape-must caramel in Balsamic vinegars of Modena and Spanish PDO wine vinegars. Univariate and multivariate calibrations were assessed for this quantification. Results demonstrated the ability of UV-vis spectroscopy coupled with multivariate calibration in the quantification of grape-must caramel, predicting caramel amounts under 2% v/v in both Balsamic and PDO wine vinegars.