Winemaking treatments significantly influence the micro/trace-element composition and stable isotopic ratios (δ¹⁸O, δ¹³C, δ¹⁵N) of wine, affecting the determination of geographic traceability, authenticity, and quality. Fining agents—including bentonite, polysaccharides, tannins, and protein-based additives—alter trace-element profiles through the introduction or removal of metals.
The interaction between wine and metallic/rare earth elements (REEs) has gained increasing research attention due to implications for wine quality, safety, and traceability. As a complex acidic matrix, wine affects the leaching, adsorption, and precipitation of metals (e.g., Fe, Cu, and Pb) and REEs during fermentation, aging, and storage. Organic wine acids (tartaric and malic) and polyphenols actively chelate metals, modifying their bioavailability and potential toxicity. While REEs serve as valuable geochemical fingerprints in terroir studies, their stability under varying pH and redox conditions during winemaking remains insufficiently characterized.
Winemaking fining agents (bentonite, proteins, etc.) can subtly alter wine’s stable isotope ratios (δ¹³C, δ¹⁵N, δ¹⁸O) by introducing exogenous elements, adsorbing metal-complexing compounds, or modifying fermentation dynamics. While effects are generally minor compared to terroir-driven isotopic signatures, unstandardized fining may impact traceability studies. Protein-based agents influence δ¹⁵N; bentonite affects δ¹³C via metal removal; and silica gels may shift δ¹⁸O. These processing-induced variations require careful calibration in isotopic authentication.
In our study, we replicated fining treatments at the laboratory scale using both artificial and commercial red/white wines to examine treatment effects on metal, REE, and stable isotopic profiles. Through combined ICP-MS and IRMS analyses as well as multivariate statistics, we demonstrated significant fining-induced compositional changes. Although multi-instruments, multi-element, and multi-isotope profiling coupled with chemometric analysis can distinguish wines by their origin despite processing effects, careful standardization and procedures are essential to account for treatment-induced variability.
