# Spectroscopic Techniques Application for Wine and Wine Byproduct Authentication
## 4 Emerging Trends in Wine and Byproduct Authentication
[168] determined the \(\delta\)13C and \(\delta\)18C in authentic wines and compared them to 29 commercial wines, concluding that only 16 were genuine, while the remaining samples showed signs of alteration. Similarly, [PERSON] et al. [169; 170] applied isotopic analysis using the \({}^{13}\)C/\({}^{12}\)C ratio of ethanol and glycerol, as well as the \({}^{18}\)O/\({}^{16}\)O ratio of water, to evaluate 600 samples of Chinese wines and verify the origin of 240 French wine samples. Their findings confirmed that stable isotope analysis offers excellent sensitivity and accuracy. However, they also noted that precision can be compromised during sample processing and storage due to the instability of the isotopic ratios [169; 170]. Integrating isotopic analysis with elemental composition measurements provides a comprehensive approach to wine authentication. This method has been successfully applied to Bordeaux wines, where isotopic ratios of hydrogen, oxygen, and carbon, along with trace element profiles, enable the differentiation of subregions and vintages [171]. Usingmultiple isotopic and elemental markers enhances the accuracy of origin determination and authenticity verification [172; 173]. Also, according to [PERSON] and [PERSON] [152], combining isotopic analysis with DNA fingerprinting provides a robust approach to assessing a wine's chemical composition and determining its geographical origin. Although isotopic analysis is considered a reliable method for determining wines' geographical origin and authenticity, several limitations can be pointed out. The geology of the source region influences the \({}^{87}\)Sr/\({}^{86}\)Sr isotopic composition in wine, particularly the bedrock and soil. Therefore, a careful assessment of the geochemical context is required to interpret isotopic data accurately, as variations in bedrock can significantly impact the wine's isotopic composition [166]. While isotopic analysis can reasonably identify regional wineries, the variability within a region can be minimal, making it challenging to distinguish between wines from closely situated vineyards [163]. Moreover, according to the same authors, natural and anthropogenic factors can introduce variations in isotopic signatures, complicating the discrimination between authentic and counterfeit wines [163]. Enological practices, such as must concentration techniques, may slightly influence isotopic values. For instance, high-vacuum evaporation can alter the oxygen-18 ratio, affecting the wine's isotopic profile [174]. The precision and accuracy of isotopic measurements depend heavily on optimized sample preparation and analytical conditions, as any deviation can compromise the reliability of the data used for wine authentication [165]. As previously mentioned, analytical techniques used for wine evaluation and authentication, such as chromatographic and spectroscopic methods, have substantial commercial applications [153]. According to [PERSON] et al. [5], promising new methods are currently being explored, with digital imaging techniques standing out due to their minimal or no sample preparation requirements. As such, analytical methods that integrate digital imaging with chemometrics represent an innovative and practical approach to wine analysis.