The application of right-angle fluorescence spectroscopy as a tool to distinguish five autochthonous commercial Greek white wines.

White wine is among the most widely consumed alcoholic beverages. Varietal discrimination of wines has received increasing attention. Today's consumers require a sense of authenticity and are deterred by falsehood or misrepresentation in product marketing. However, wine can involve various types of frauds, which directly affects the distribution of wine in national and international markets. Right-angle fluorescence spectroscopy is a simple and rapid analytical technique that in combination with chemometric algorithms, constitutes a novel method for wine authentication. In this study, the stepwise-Linear Discriminant Analysis algorithm was applied in three representative spectral regions related to phenolic compounds for the purpose of distinguishing white wines according to the grape variety. The wavelength at 310 nm attributed to the hydroxycinnamic acids and stilbene provided a higher classification rate (95.5%) than the λex 280 and 295 nm regions (79.8%), suggesting that these compounds are highly related to the botanical origin of samples. The chemometric models were validated utilizing cross-validation and an external validation set to enhance the robustness of the proposed methodology. The above-mentioned methodology constitutes a powerful tool for the varietal discrimination of white wines and can be used in industrial setting. The ultimate goal of this study is to contribute to the efforts towards the authentication of Greek white wine which will eventually support producers and suppliers to remain competitive and simultaneously protect the consumers from fraudulent practices.

Proanthocyanidin content as an astringency estimation tool and maturation index in red and white winemaking technology.

Selecting the appropriate type of barrel for wine maturation but also deciding on the optimum maturation length, is a challenge for winemakers. As different types of barrel woods emerge, it is of great importance for a guideline to be established, which could facilitate winemaking decisions. Since the sensory perception of the finished wine, and particularly the intensity of astringency, is a decisive factor for the quality of a barrel-aged wine, in this experiment, the structural characteristics of wine proanthocyanidins were determined and their correlation with astringency was established. According to the results obtained, the proanthocyanidin content and the type of subunit that is dominant in tannin chains could be used to construct an astringency estimation model. The findings could provide winemakers with a useful tool when deciding how long to mature a specific type of wine in a specific wood container without making it appear coarse and astringent.