Wine analysis is a complex field that ensures wine maintains its expected quality and authenticity. Advanced testing methods are used to safeguard the integrity of the wine, ensuring that it meets the highest standards for safety, sensory experience, and provenance.
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Background
A blend of water, sugars, organic acids, and ethanol, enriched by compounds like glycerol, aromatic alcohols, and polyphenols, contributes to wine’s color, aroma, and flavor. Although all wines are made with a common process, several factors contribute to the creation of different wine types and varieties, including the environment and production method.
The diversity and quality of wines are a result of grape variety, soil characteristics, vineyard location, and climate, as well as additives added in the fermentation process.
There is great demand for rigorous testing to ensure wines meet high standards of safety, quality, and authenticity, preserving both product integrity and consumer confidence.
Quality Control in Wine Production
By analyzing wine’s sensory profile, and its chemical and microbial composition, winemakers assess that every wine reflects the intended style and taste. In addition, since the numerous bioactive compounds contained in wine can influence the health of the consumer, it is important to ensure products meet safety standards and are not harmful.
Chemical analysis of sugars, organic acids, polyphenols and aromatic alcohols is used to assess properties like acidity, sweetness, alcohol content, and phenolic content, all of which play key roles in the wine’s taste and aging potential.
In sensory analysis, trained tasters or tasting panels evaluate wine for its taste, aroma, and texture, ensuring the wine’s profile aligns with expectations. This form of quality control captures subtle qualities, like mouthfeel or specific flavor notes, that may not be quantifiable but are essential to the consumer experience.
Unwanted bacteria or yeasts can negatively impact the flavor of wine or even cause spoilage. Microbial testing at critical stages of the fermentation process and storage is essential to prevent contamination and ensure only desirable microorganisms influence the final product.
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Methods Used in Wine Analysis
Wine analysis uses advanced techniques to assess the many aspects of wine composition, quality, and authenticity. For instance, chromatography, including gas chromatography (GC) and high-performance liquid chromatography (HPLC), allows for the separation and identification of different compounds within a wine sample, providing insights on flavor profile and purity.1
GC is especially effective at analyzing volatile molecules like alcohols and aromatic compounds. HPLC is ideal for non-volatile substances like sugars, acids (e.g., hydroxybenzoic acids), and polyphenols, and is used for the determination of glycerol and ethanol.
Techniques like ultraviolet (UV) and infrared (IR) spectroscopy provide valuable data on organic compounds and chemical composition, while nuclear magnetic resonance (NMR) spectroscopy enables a deeper understanding of molecular structures, identifying complex impurities that could compromise quality.2
Chromophores such as hydroxybenzoic and hydroxycinnamic acids can be detected via UV spectroscopy, with absorption peaks at 280 nm and 320 nm, respectively. In middle-IR spectroscopy, the 1500-400 cm−1 region includes unique absorption patterns typical of phenolic compounds and can be used for discrimination purposes.
When paired with chromatography, mass spectrometry can confirm the presence of specific compounds in wine, at low concentrations. This technique is particularly valuable in authenticity testing, as it allows for the detection of trace elements that could reveal adulteration, contamination, or even the geographic origin of a wine.
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Authenticity Verification
In addition to ensuring quality, wine analysis is essential for verifying authenticity. Wine is one of the most adulterated foods, and with wine fraud being a growing concern, accurate methods to prove the origin and varietal accuracy of wines are crucial to build consumers trust and help tackle criminal activities.3
The assessment of wines’ geographical indications is closely linked to their origin. Wines from different regions are characterized by various types of designations, which are particularly important for region-specific or high-value wines.
Since environmental factors influence isotope ratios (e.g., D/H, 13C/12C, 18O/16O), wines from different regions show distinct isotope profiles. Hence, isotope ratio analysis can be a powerful tool for authenticating a wine’s geographic origin.
DNA profiling of grapes is another technique used for wine authenticity verification and enables precise identification of grape varieties. By analyzing grape DNA, wineries can confirm the varietals used and, in some cases, verify the authenticity of older vintages.4
Trace elements in wine are often influenced by the soil, climate, and environment in which the grapes were grown. Using techniques such as atomic emission spectroscopy and inductively coupled plasma-mass spectrometry (ICP-MS) it is possible to discriminate wines using elemental fingerprints through the analysis of Ba, Cs, Cu, Mg, and many others.
By profiling these elements, it is possible to link a wine to a particular terroir or even a specific vineyard, adding a valuable layer of verification for wines marketed based on their unique origins.5
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Conclusion
By employing advanced analytical techniques, wine analysis is fundamental to maintaining the industry’s standards of quality, safety, and authenticity. From chemical composition profiling and microbial testing to sensory evaluation and authenticity verification, wine analysis provides a comprehensive understanding of wine’s composition and origin.
Not only does it help safeguard consumer health and ensure product consistency, but it is also crucial to authenticity verification and maintaining trust among consumers.
References
- Pisaniello, L., Watson, F., Siebert, T., Francis, L. & Hixson, J. L. (2022). The Varietal Influence of Flavour Precursors from Grape Marc on Monoterpene and C(13)-Norisoprenoid Profiles in Wine as Determined by Membrane-Assisted Solvent Extraction (MASE) GC-MS. Molecules, 27.10.3390/molecules27072046.
- Ranaweera, R. K. R., Capone, D. L., Bastian, S. E. P., Cozzolino, D. & Jeffery, D. W. (2021). A Review of Wine Authentication Using Spectroscopic Approaches in Combination with Chemometrics. Molecules, 26.10.3390/molecules26144334.
- Popîrdă, A., Luchian, C. E., Cotea, V. V., Colibaba, L. C., Scutarașu, E. C. & Toader, A. M. (2021). A Review of Representative Methods Used in Wine Authentication. Agriculture, 11, 225. Available: https://www.mdpi.com/2077-0472/11/3/225
- Galstyan, A. G., Semipyatniy, V. K., Mikhailova, I. Y., Gilmanov, K. K., Bigaeva, A. V. & Vafin, R. R. (2021). Methodological Approaches to DNA Authentication of Foods, Wines and Raw Materials for Their Production. Foods, 10.10.3390/foods10030595.
- Tanabe, C. K., Nelson, J., Boulton, R. B., Ebeler, S. E. & Hopfer, H. (2020). The Use of Macro, Micro, and Trace Elemental Profiles to Differentiate Commercial Single Vineyard Pinot noir Wines at a Sub-Regional Level. Molecules, 25, 2552. Available: https://www.mdpi.com/1420-3049/25/11/2552
Further Reading