Comparison of organic compounds in natural wine, red wine and grape juice by HPLC

Importance of the Topic

Natural and traditional wines have gained momentum among consumers who seek minimal intervention products. Accurate profiling of organic acids, sugars, alcohols and phenolic compounds is essential for quality control, regulatory compliance and product authentication in the beverage industry. High performance liquid chromatography (HPLC) offers a versatile platform for comprehensive analysis of these key constituents in wines and grape juice.

Study Objectives and Overview

This study aimed to compare the concentrations of major organic compounds in natural wine, two red wines and grape juice. Two rapid chromatographic methods were developed. The first combined ion exchange separation on Eurokat columns with refractive index detection (RID) and diode array detection (DAD) to quantify sugars, organic acids and alcohols. The second employed reversed-phase C18 chromatography with DAD to profile phenolic acids and flavonoids. A total of about 20 analytes were targeted across both assays.

Methodology

Sample preparation required only filtration through a 0.45 µm cellulose acetate filter and simple dilution. Standard mixtures of organic acids, sugars, alcohols and phenolic compounds were prepared in water or water–organic solvent mixtures at defined concentrations. Chromatographic conditions were optimized for resolution, detector response and analysis time.

Used Instrumentation

• HPLC pump with low-pressure gradient capability
• AZURA DAD 2.1L diode array detector
• AZURA RID 2.1L refractive index detector
• AZURA AS 6.1L autosampler
• AZURA CT 2.1L column thermostat
• Eurokat H and Eurokat Ca ion exchange columns
• Eurospher II C18 reversed-phase column

Key Results and Discussion

Ion exchange HPLC showed that natural wine contained no residual sugars but featured tartaric, succinic and acetic acids plus glycerol and ethanol. Red wines displayed lower sugar levels than grape juice, but higher ethanol. Grape juice was rich in glucose and fructose, and also contained malic and tartaric acids. The Eurokat Ca column improved sugar separation but co-elution of glycerol and ethanol required dual RID and DAD monitoring for confirmation.

Reversed-phase analysis separated seven phenolic targets. Syringic acid and quercetin were present in all samples. p-Coumaric acid appeared in red wines and grape juice but not in natural wine, consistent with its microbial conversion in minimal-intervention fermentations. Signal intensities highlighted relative abundance trends across beverages.

Benefits and Practical Applications

• Rapid simultaneous detection of sugars, acids and alcohols without extensive sample cleanup
• Use of water as primary eluent for ion exchange assays reduces environmental impact
• Combined RID and DAD detection extends analyte coverage and aids peak confirmation
• Reversed-phase DAD method profiles key phenolics that influence taste and stability
• Applicable for quality control, process monitoring and product authentication in wineries

Future Trends and Opportunities

Advances in mass spectrometry coupling could enhance sensitivity and broaden compound identification. Miniaturized and high-throughput HPLC platforms offer potential for in-line monitoring during fermentation. Green solvent alternatives and chemometric data analysis will further refine beverage profiling and authenticity verification. Integration with online sensor networks could support real-time quality control in production facilities.

Conclusion

The dual HPLC strategies described provide a straightforward and effective approach to characterize organic acids, sugars, alcohols and phenolic compounds in natural wine, red wine and grape juice. Minimal sample preparation, combined detectors and optimized columns deliver comprehensive profiles to support quality assurance, regulatory compliance and product development in the wine industry.

Reference

1. Kelebek H, et al. HPLC determination of organic acids, sugars, phenolics and antioxidant capacity of orange juice and orange wine. Microchem J. 2009;91(2).
2. Webendorfer U, Haim K. Weinanalyse. PH OÖ. 2013.
3. Kerem Z, et al. Rapid LC–UV determination of organic acids and phenolics in red wine. J Chrom A. 2004;1052(1–2):211–215.
4. GL Sciences. LC Technical Note LT192: Analysis of malic acid by HPLC.
5. Vodnar D, Socaciu C. Comparative analysis of lactic acid produced by apple fermentation using HPLC and biosensor. Bull USAMV Cluj. 2008;65(2):444–449.
6. Georgiev V, Ananga A, Tsolova V. Uses of grape flavonoids as nutraceuticals. Nutrients. 2014;6(1):391–415.
7. Carneiro C, et al. Geographical characterization of South America wines based on phenolic and melatonin composition. Microchem J. 2020;158:105240.
8. Salameh D, et al. Problems generated by p-coumaric acid analysis in wine fermentations. Food Chem. 2008;107(4):1661–1667.
9. Branco P, et al. Wine spoilage control: Impact of saccharomycin on Brettanomyces bruxellensis and its conjugated effect with SO2. Microorganisms. 2021;9(12):2528.