# Spectroscopic Techniques Application for Wine and Wine Byproduct Authentication
## 1 Introduction  
The geographical origin, composition, grape variety identification, and production methods of wine and its byproducts are essential factors in determining quality, authenticity, and food safety. Awareness of all these characteristics is a growing concern for both consumers and the wine industry [1, 2]. Produced through the alcoholic fermentation of fresh white or red grape must, wine holds significant economic value. According to the International Organization of Vine and Wine (OIV) [3], global wine production in 2024 reached 226 million hectoliters, with consumption estimated at 214 million hectoliters in 2024. Due to rising prices, wine is highly susceptible to adulteration, particularly in the case of wines from prestigious producers. Although most producers issue certificates of authenticity, wine fraud continues to rise, driven by increased trade on digital platforms [4, 5]. Fraud can take various forms, most commonly involving the misrepresentation of grapevariety and geographical origin, the addition of sugar, flavor enhancers, and colorants, as well as false labeling [6]. Analytical methods for wine authentication typically focus on the analysis of volatile compounds, phenolic compounds, amino acids, elements, or isotopes [4]. These analyses rely on advanced and costly technologies such as high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), isotope ratio mass spectrometry (IRMS), and inductively coupled plasma mass spectrometry (ICP-MS). While highly accurate and reliable, these techniques are generally not accessible for routine application--particularly in small to medium-sized wineries or operations with limited resources. They require expensive instrumentation, regular maintenance, specialized facilities, and trained personnel for proper operation and data interpretation. However, it is important to note that in large-scale laboratories and research institutions equipped with the necessary infrastructure, methods like HPLC and GC-MS are widely and effectively used as standard analytical tools. In such contexts, the associated costs and complexity are justified by the high volume of analyses, regulatory demands, and the need for precise, reproducible data. Recent advancements in analytical techniques for assessing wine's physicochemical and organoleptic characteristics, aging process [7], geographical origin, and grape varieties [8; 9] primarily rely on chromatographic methods, inductively coupled plasma mass spectrometry (ICP-MS), and nuclear magnetic resonance (NMR) spectroscopy [10; 11]. While these methods provide critical insights, widespread implementation is challenging due to high costs [12]. As a result, researchers are increasingly focusing on spectroscopic techniques for wine classification and authentication, as they offer highly accurate, reliable, simple, and cost-effective methodologies [13; 14; 15]. Several studies have demonstrated the effectiveness of combining spectroscopic techniques to identify a wine fingerprint with high precision. [PERSON] et al. [15] and [PERSON] et al. [16] successfully classified Sauvignon Blanc and Shiraz wines from different regions of Australia and New Zealand based on geographical origin using ultraviolet-visible (UV-Vis), near-infrared (NIR), and mid-infrared (MIR) spectroscopy combined with multivariate data analysis (chemometrics). [PERSON] et al. [17] authenticated Australian Cabernet Sauvignon wines by integrating spectrofluorometric and multi-element techniques with multivariate statistical modeling. Similarly, [PERSON] et al. [12] employed UV-Vis spectroscopy to differentiate between the grape variety, aging period, and type of container for red and white wines from Crete. Given these findings, understanding the origin of wine and its byproducts is crucial for assessing authenticity and typicality, ultimately enhancing consumer's perception of quality [18]. Validated analytical techniques, supported by updated databases, are essential for reliably determining and authenticating wine origins.