Using HPLC to Compare Chemical Makeup of Grapes

A recent study took a close look at three grape varieties, Bronner, Muscaris, and Morava, examining what their bunches and berries look like, how they're structured, and what they're made of chemically. To measure the sugars and organic acids in the grapes, the researchers used high performance liquid chromatography (HPLC). For the phenolic compounds (natural plant chemicals that influence color, flavor, and health properties), HPLC–mass spectrometry (MS) was used. A paper based on this work was published in the journal Plants.¹

Why Do Sugar and Acid Levels in Grapes Matter So Much for Wine Quality and Harvest Timing?

Sugars and acids are basically the backbone of good wine, they shape how sweet or tart it tastes, how well it ferments, how stable it is against unwanted microbes, and how it ultimately comes across to the palate.² Acids, particularly tartaric and malic acid, are especially important for keeping a wine's pH balanced, its flavor crisp and fresh, its color steady, and its overall stability over time. Meanwhile, the sugar level determines both sweetness and how much alcohol the wine can potentially reach once fermentation kicks in.^3-5 As grapes ripen, winemakers keep a close eye on the tug-of-war between sugar buildup (mostly glucose and fructose) and acid levels (mostly tartaric and malic), since that balance is one of the best signals for knowing exactly when the grapes are ready to pick.⁶

How Do Bronner, Muscaris, and Morava Compare, and Which Suits Which Wine Style?

The researchers report that Morava and Muscaris grapes had a greener skin tone, while Bronner leaned more yellow. When it came to bunch size, Muscaris and Bronner produced heavier bunches than Morava, though all three varieties had roughly the same berry weight. Bronner had the tartest juice (highest acidity), while Muscaris was the sweetest. Flavanols turned out to be the dominant compound in the grapes, making up 76–88% of all the phenolic content (the natural compounds that affect flavor, color, and health benefits). Bronner and Muscaris had the most flavanols (a type of chemical compound found in various fruits, vegetables, and plants that research suggests may have antioxidative, anti-inflammatory, and antiviral properties)⁷ and caftaric acid (a wine compound winemakers use to gauge oxidation levels, since it depletes quickly in heavily oxidized wines like press wines),⁸ while Morava led in flavonols (which are known to promote nitric oxide concentration in blood and enhance endothelial functions, contributing to cardiovascular health).⁹ All three varieties produced good-quality grapes and juice, so they're all solid choices for winemaking. Bronner and Muscaris stand out thanks to their bigger bunches and rich phenolic content, both of which boost taste and overall wine quality. Muscaris, with its high sugar content, is a great pick for wines with a higher alcohol kick, while Bronner, with its higher acidity, suits wines that need more tartness or zing.¹

The researchers are of the opinion that future studies should focus on how these grape varieties actually produce their phenolic compounds at a biological level, and also look at how the combination of genetics and growing environment (climate, soil, etc.) shapes both the phenolic makeup of the grapes and the aromas that end up in the wine.¹

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References

1. Mikulic-Petkovsek, M.; Jovanović-Cvetković, T.; Krošelj, S. et al. Comparative Evaluation and Physicochemical Characterisation of Three Tolerant Interspecific Grape Cultivars. Plants 2026, 15 (11), 1663. DOI: 10.3390/plants15111663
2. Wang, C. N.; Wang, L. A.; Ye, J. B. Fruit Quality of Vitis vinifera: How Plant Metabolites are Affected by Genetic, Environmental, and Agronomic Factors. Sci. Hortic. 2022, 305, 111404. DOI: /10.1016/j.scienta.2022.111404
3. Li, M. H.; Su, J.; Yang, H. Q. et al. Grape Tartaric Acid: Chemistry, Function, Metabolism, and Regulation. Horticulturae 2023, 9, 1173. DOI: 10.3390/horticulturae9111173
4. Li, J. X.; Zhang, C. L.; Liu, H. et al. Profiles of Sugar and Organic Acid of Fruit Juices: A Comparative Study and Implication for Authentication. J. Food Qual. 2020, 2020, 7236534. DOI: 10.1155/2020/7236534
5. Payan, C.; Gancel, A. L.; Jourdes, M. et al. Wine Acidification Methods: A Review. Oeno One 2023, 57, 113–126. DOI: 10.20870/oeno-one.2023.57.3.7476
6. Lu, L. Z.; Delrot, S.; Liang, Z. C. From Acidity to Sweetness: A Comprehensive Review of Carbon Accumulation in Grape Berries. Mol. Hortic. 2024, 4, 22. DOI: 10.1186/s43897-024-00100-8
7. What Are Flavanols? Medical News Today website. https://www.medicalnewstoday.com/articles/flavanols (accessed 2026-06-17)
8. Caftaric acid. Wikipedia website. https://en.wikipedia.org/wiki/Caftaric_acid (accessed 2026-06-17)
9. Flavonol. ScienceDirect website. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/flavonol (accessed 2026-06-17)