# Spectroscopic Techniques Application for Wine and Wine Byproduct Authentication
## 2 Food Spectral Print Approaches
### Fluorescence
nols vary between grape varieties, with additional complexity introduced by reactions that occur during winemaking and aging. Front-face fluorescence spectroscopy, combined with chemometric methods, has been investigated for its ability to discriminate wines based on variety, typicality, and vintage. A study analyzing 120 wines from France and Germany utilized fluorescence spectroscopy to record emission spectra (275-450 nm) and excitation spectra (250-350 nm) directly from the wine samples. The emission spectra exhibited a maximum at 376 nm and a shoulder at 315 nm, while the excitation spectra displayed two peaks at approximately 260 and 320 nm. Spectral shape and intensity variations enabled differentiation based on wine origin and characteristics [80]. Rapid fluorescence measurements applied directly to wines have also been used to monitor varietal characteristics, typicality, and vintage classification. These findings confirm that front-face fluorescence spectroscopy, combined with chemometric analysis, is a promising approach for wine authentication. The technique is nondestructive, rapid, easy to use, and cost-effective [80]. In recent years, fluorescence spectroscopic techniques have developed intensively due to the simplicity of the required equipment and the advantages they offer. These methods are fast, noninvasive, highly sensitive, and relatively low-cost. Fluorescence techniques provide crucial information about fluorescent molecules and their environments in biological and food samples. They are reported to be 100-1000 times more sensitive than other spectroscopic techniques [83]. The role of fluorescence spectroscopy in wine analysis continues to expand. Phenolic compounds in grapes and wines form a diverse group of fluorescent molecules. Studies have demonstrated the potential of fluorescence spectroscopy for providing unique spectral fingerprints, allowing the identification of wines based on variety and typicality [17; 80]. Furthermore, ref. [18] demonstrated that chlorophyll fluorescence can be utilized to assess anthocyanin content in grapes, underscoring the versatility of fluorescence-based methods in viticulture. Distilled spirits' fluorescence spectra contain overlapping bands that reflect chemical, physical, and structural information. As a result, conventional fluorescence techniques that rely on single emission or excitation spectra may be inadequate for analyzing spirit drinks. Advanced methods, such as total luminescence or synchronous scanning fluorescence, combined with multivariate and multiway analytical techniques, enhance sample classification, identification, and property determination [84]. Fluorescence spectroscopy is a valuable tool for authenticating food and wine. It enables rapid, non-destructive analysis, allowing researchers and producers to obtain characteristic fingerprints of products in seconds. When combined with chemometric techniques, fluorescence spectroscopy becomes even more potent for authenticating wines based on grape variety, processing conditions, and aging. This high sensitivity makes it a valuable tool for verifying wines based on variety [22; 85; 86] or geographical origin [22; 80]. Its potential is further enhanced when combined with chemometric techniques [22; 85; 86]. Despite its promise, research on integrating fluorescence spectroscopy with chemometric methods remains limited. Further studies are needed to strengthen wine authentication and enhance its acceptance in international markets [22].