Alcoholic beverages represent a sector of significant economic and cultural importance but are also susceptible to fraud and adulteration, which can compromise their quality and authenticity. Isotopic analyses have become increasingly valuable tools for tracing the geographical origin and ensuring the quality control of products such as wine, beer, and distilled spirits. This literature review examines the main isotopic analysis techniques employed in this field, including Isotope Ratio Mass Spectrometry (IRMS) and Site-Specific Natural Isotope Fractionation by Nuclear Magnetic Resonance (SNIF-NMR), with a particular focus on the insights derived from the isotopic ratios of various elements, notably δ(²H), δ(¹³C), δ(¹⁸O), δ(¹⁵N) and δ(³⁴S).

Among the Moscato grapes, Moscato Giallo is a winegrape variety characterised by a high content of free and glycosylated monoterpenoids, which gives wines very intense notes of ripe fruit and flowers. The aromatic bouquet of Moscato Giallo is strongly influenced by the high concentration of linalool, geraniol, linalool oxides, limonene, α-terpineol, citronellol, hotrienol, diendiols, trans/cis-8-hydroxy linalool, geranic acid and myrcene, that give citrus, rose, and peach notes. Except for quali-quantitative analysis, no investigations regarding the isotopic values of the target volatile compounds in grapes and wines are documented in the literature. Nevertheless, the analysis of the stable isotope ratio represents a modern and powerful tool used by the laboratories responsible for official consumer protection, for food quality and genuineness assessment. To this aim, the aromatic compounds extracted from grapes and wine were analysed both by GC-MS/MS, to define the aroma profiles, and by GC-C/Py-IRMS, for a preliminary isotope compound-specific investigation. Seventeen samples of Moscato Giallo grapes were collected during the harvest season in 2021 from two Italian regions renowned for the cultivation of this aromatic variety, Trentino Alto Adige and Veneto, and the corresponding wines were produced at micro-winery scale. The GC-MS/MS analysis confirmed the presence of the typical terpenoids both in glycosylated and free forms, responsible for the characteristic aroma of the Moscato Giallo variety, while the compound-specific isotope ratio analysis allowed us to determine the carbon (δ¹³C) and hydrogen (δ²H) isotopic signatures of the major volatile compounds for the first time.

Stable isotope ratio analysis of carbon (δ¹³C) and hydrogen (δ²H) in vanillin has become a valuable tool for differentiating natural vanilla from synthetic or biosynthetic alternatives and for tracing its geographical origins. However, increasingly sophisticated fraud techniques necessitate ongoing refinement of analytical methods to ensure accurate detection. This study advanced the field by investigating minor volatile organic compounds as potential biomarkers for identifying botanical and geographical origins of vanilla products. Vanilla pods from the two main vanilla species, V. planifolia and V. tahitensis, were investigated using GC-MS/MS to analyze their aromatic profile and GC-C/Py-IRMS to determine compound-specific isotope ratios, providing, for the first time, detailed and authentic isotopic and aromatic profiles. Additionally, the potential natural presence of ethyl vanillin and its corresponding glucoside precursors—molecules commonly used as synthetic vanilla-scented fragrance agents in various foods and industrial products—was explored using UHPLC-HRMS. These findings contribute to robust methods for verifying vanilla authenticity, addressing flavor complexity and isotopic composition, and enhancing the detection of adulteration in vanilla-flavored products.

Food fraud is a matter of great interest, particularly when organic productions are involved. Therefore, policymakers and institutions are asked to introduce new effective official control methods, not only based on documentary compliance to EU regulations. Lately, an integrated approach based on the use of isotopic, chemical and biological data treated by chemometrics has been suggested to authenticate organic products. The present research aims to validate the beforementioned integrated approach for the reliable classification of organically and conventionally grown fennel productions obtained by applying different treatments at diverse percentages of mineral fertilizers. Moreover, to the best of our knowledge, for the first time, an N-fixing plant (alfalfa), as an agroecological service crop in intercropping fennel, was introduced. Physicochemical parameters (fresh weight, total soluble solids, total acidity, consistency, Commission Internationale de l’Eclairage (CIE) lightness (L*), green-red (a*), blue-yellow (b*) color components), total phenolic content, in vitro antioxidant activity, total and inorganic N, and stable isotope ratios (¹⁵N/¹⁴N, ¹³C/¹²C, and ³⁴S/³²S) analyses were performed over a two-year field trial and further multivariate discriminant analysis was performed. The physicochemical parameters were not affected by the differential growing practice while antioxidant activity showed higher values in the organic treatments. The conventional treatments increased the NO₃⁻ values over 440% compared to the organic ones and the lowest values were found when alfalfa was used for intercropping. δ(¹⁵N) of fennel, δ(³⁴S) of fennel and δ(¹⁵N) of leaves showed great discriminatory potential, with respect to the applied agronomic practice. However, these parameters alone were not sufficient as biomarkers for differentiating cultivation methods. Instead, the proposed innovative tool demonstrated that only a comprehensive multivariate approach was able to achieve a correct classification of grouped cases. Furthermore, the discrimination between organic and conventional horticultural products showed feasible results, even when N-fixing plants were incorporated in organic practice, thus avoiding misinterpretations solely based on the isotopic N fingerprint. These promising findings highlight the potential of this method and suggest that further research should extend its application to other horticultural crops to confirm and expand upon the current results.

Compound-Specific Isotope Analysis (CSIA) of amino acids (AAs) is increasingly applied in food authentication and environmental studies, where precise and accurate δ¹³C measurements are essential. This study systematically compares the performance of Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS) and Liquid Chromatography coupled to Isotope Ratio Mass Spectrometry (LC-co-IRMS) for δ¹³C analysis of essential and non-essential AAs. The GC-C-IRMS showed high analytical precision, with standard deviations typically below 0.5 ‰ for standard AAs and 0.8 ‰ for rice samples, in close agreement with EA-IRMS reference values. The LC-co-IRMS, while generally reliable, exhibited higher variability, with deviations up to 1.6 ‰ for standard AAs and 1.9 ‰ for samples. The GC-C-IRMS also provided better chromatographic resolution, shorter run times, and broader amino acid coverage but involved complex workflows, including derivatization and the use of hazardous reagents. In contrast, LC-co-IRMS offered a simpler, safer protocol with fewer correction steps, though with longer analysis times, reduced throughput, and higher water consumption. Despite these trade-offs, both methods yielded comparable δ¹³C values overall, with some differences for specific AAs. This study finds GC-C-IRMS as suitable for high-precision, high-throughput applications, while LC-co-IRMS is more appropriate for simplified, sustainable workflows, with method selection depending on research purposes and operational priorities.