Wine

1. Brief Description

Wine is one of the oldest and most economically significant fermented beverages in the world, produced from the fermentation of grape must (Vitis vinifera and hybrids) across regions with strongly protected identities (Appellations of Origin, PDO/PGI in the EU, DOC/DOCG in Italy, AVA in the US). Its quality and commercial value depend on a chain of chemical parameters that evolve from the vineyard through fermentation to the bottled product: sugar content (Brix), acidity, pH, alcohol, phenolic compounds (anthocyanins, tannins), and volatile aroma compounds.^1,2

Historically, winemakers and quality inspectors have relied on manual sampling and wet-chemistry lab analysis (titration, HPLC, enzymatic assays) to track these parameters, alongside sensory tasting panels for style and defect assessment.^2,5 These methods are accurate but slow, destructive, and often only provide a snapshot from a small sample rather than continuous, representative data across a tank, a vineyard block, or a shipment.

2. The Problem

Traditional wine and grape quality control faces several vulnerabilities across the value chain:

• Snapshot sampling: lab analysis is performed on small grab samples, which may not represent the full heterogeneity of a vineyard block, a fermentation tank, or a bulk shipment.
• Slow feedback during fermentation: sugar, alcohol, and acidity change constantly during fermentation; conventional lab turnaround times mean winemakers often react to conditions that have already changed by the time results arrive.
• Subjectivity of sensory panels: tasting-based quality and defect classification depends on trained panels, which can vary between tasters and sessions, and cannot be scaled to every lot or delivery.
• Fraud and mislabeling: given the large price gap between wines from protected appellations or premium varietals and generic/blended wines, there is strong economic incentive for origin or varietal misrepresentation, and for undeclared additions (water, sugar, foreign alcohol^6,7).
• Cost and destructiveness of lab methods: reference methods such as HPLC, enzymatic kits, and wet titration are accurate but require reagents, trained staff, and sample destruction, making them impractical for continuous, in-line monitoring of every batch or delivery.^2,5
• Harvest timing decisions: determining the optimal harvest date depends on ripeness parameters (sugar, acidity, phenolics) that traditionally require sending must samples to a lab, delaying a decision that is highly time-sensitive.

3. How NIR Can Contribute at Each Step

The value chain runs from the vineyard to the bottled, market-ready wine. NIR can be applied at several key stages, replacing destructive lab titration or subjective tasting with fast, non-destructive, objective measurements, provided the models are properly calibrated and validated.^1,5

Parameters that can be measured by NIR in Wine

In a non-destructive, fast and objective way, NIR can quantify several of the traits that traditionally depended on wet-chemistry lab analysis or sensory judgment:

The chain, step by step

• 1. Viticulture. Grapevines are cultivated according to varietal, terroir and appellation regulations, with vineyard management (canopy, irrigation, yield control) shaping the final grape composition.
• 2. Ripening and harvest decision. As grapes mature, sugar rises and acidity drops; winemakers must decide the optimal harvest date, balancing sugar, acid and phenolic development.^2,4
• 3. Harvest. Grapes are picked by hand or machine, depending on the style and appellation requirements.
• 4. Reception and crushing. Grapes arrive at the winery, are sorted, destemmed and crushed to release the must (for white wines, pressed before fermentation; for reds, often fermented on the skins).
• 5. Fermentation. Yeast converts sugars into alcohol and CO2 over days to weeks; winemakers monitor sugar depletion, temperature and acidity throughout to guide the process.⁵
• 6. Malolactic fermentation (optional, mainly reds). Bacteria convert sharp malic acid into softer lactic acid, adjusting the final acid profile.
• 7. Pressing and racking. The wine is separated from skins, seeds and lees, and clarified.
• 8. Aging. Wine matures in stainless steel, concrete or oak barrels for a period ranging from months to years, developing structure, color stability and aroma complexity.
• 9. Blending. Winemakers may blend different lots, varietals or vintages to achieve a consistent final style.
• 10. Stabilization and filtration. The wine is stabilized (cold, protein, tartrate) and filtered before bottling to ensure clarity and microbial safety.
• 11. Bottling. The finished wine is bottled, corked or capped, and labeled according to appellation and export regulations.
• 12. Export and distribution. Wine is shipped domestically or internationally, passing through importers, distributors and retailers, each relying on label claims and certificates of origin/varietal.
• 13. Retail and final consumption. The end consumer purchases the wine trusting the vintage, varietal and origin declared on the label, generally with no independent way to verify it at the point of sale.^6,7

4. Who Can Benefit from This Technology

• Growers and vineyard managers: benefit at the on-vine ripening monitoring step, deciding the optimal harvest date based on objective sugar, acidity and phenolic data rather than periodic lab sampling alone.^2,4
• Winemakers / cellar teams: benefit at the fermentation monitoring step, tracking sugar depletion, alcohol formation and acidity in near real time to make faster, better-informed winemaking decisions.⁵
• Quality control laboratories: benefit at the pre-bottling QC step, screening every batch quickly for compliance (alcohol, SO2, acidity) before committing to bottling runs.¹
• Importers/distributors: benefit at the goods receiving step, verifying that bulk or bottled shipments match the declared alcohol content, varietal and origin before redistribution.^6,7
• Certifiers / appellation authorities: benefit at the compliance audit step, gaining an objective, repeatable tool to validate origin and varietal claims faster and more cheaply than traditional lab analysis or sensory panels alone.^6,7
• End consumer: benefits indirectly at every step above, through greater confidence that the vintage, varietal and origin stated on the label are accurate.⁶

5. References

1. Cozzolino D, Cynkar W, Janik L, Dambergs RG, Gishen M. Analysis of grapes and wine by near infrared spectroscopy. J Near Infrared Spectrosc. 2006;14:279-289. Available from: JNIRS 2006
2. Cozzolino D. The role of visible and infrared spectroscopy combined with chemometrics to measure phenolic compounds in grape and wine samples. Molecules. 2015;20:726-737. Available from: Molecules 2015
3. Cozzolino D, Cynkar W, Dambergs R, Mercurio M, Smith P. Measurement of condensed tannins and dry matter in red grape homogenates using near infrared spectroscopy and partial least squares. J Agric Food Chem. 2008;56:7631-7636. Available from: J Agric Food Chem 2008
4. Ferrer-Gallego R, Hernández-Hierro JM, Rivas-Gonzalo JC, Escribano-Bailón MT. Determination of phenolic compounds of grape skins during ripening by NIR spectroscopy. LWT Food Sci Technol. 2011;44:847-853. Available from: LWT 2011
5. Cozzolino D, Shah N, Cynkar WU, Smith P. Technical solutions for analysis of grape juice, must and wine: the role of infrared spectroscopy and chemometrics. Anal Bioanal Chem. 2011;401:1479-1488. Available from: Anal Bioanal Chem 2011
6. Ranaweera KRR, Capone DL, Bastian SEP, Cozzolino D, Jeffery DW. A review of wine authentication using spectroscopic approaches in combination with chemometrics. Molecules. 2021;26:4334. Available from: Molecules 2021
7. De Villiers A, Alberts P, Tredoux AG, Nieuwoudt HH. Analytical techniques for wine analysis: an African perspective. Anal Chim Acta. 2012;730:2-23. Available from: Anal Chim Acta 2012
8. Bauer R, Nieuwoudt HH, Bauer FF, Kossmann J, Koch KR, Esbensen KH. FTIR spectroscopy for grape and wine analysis. Anal Chem. 2008;80:1371-1379. Available from: Anal Chem 2008