Determination of Organic Acids in Fruit Juices and Wines by High-Pressure IC

Importance of the Topic

Organic acid profiling in fruit juices and wines is critical for flavor, stability, microbiological control and authenticity testing. Quantitative analysis of individual acids guides quality assurance in production and helps detect adulteration.

Objectives and Study Overview

This work presents development of a high‐pressure ion chromatography method with suppressed conductivity detection to determine organic acids in fruit juices and wines. Key goals were high resolution of up to 30 inorganic and organic anions, accurate quantitation, and robust authenticity assessment.

Methodology and Instrumentation

The method uses a Thermo Scientific Dionex ICS‐5000+ HPIC system with:

• IonPac AS11‐HC‐4 µm guard and analytical columns
• EGC 500 KOH eluent generator cartridge and CR‐ATC 500 anion trap column
• ASRS 300 self‐regenerating suppressor operated in external water mode
• Suppressed conductivity detection
• Hydroxide gradient elution with 1–60 mM KOH and 7–11 % methanol
• Flow rate 0.4 mL/min, injection volume 2.5 µL

Samples (apple, grape, pomegranate, blueberry juices and Merlot, Chardonnay, White Zinfandel wines) were diluted 1:20, filtered and spiked for recovery studies.

Main Results and Discussion

The AS11‐HC‐4 µm column delivered superior peak efficiencies and resolution over the 9 µm version, especially for closely eluting pairs (acetate/glycolate, succinate/malate, malonate/tartrate, fumarate/oxalate). Calibration for galacturonate, malate, tartrate and citrate showed quadratic fits (r2 > 0.999) over 1–500 mg/L, limits of detection 0.036–0.069 mg/L and quantitation 0.12–0.23 mg/L. Typical reproducibility was <4 % RSD in peak area and <0.04 % in retention time. Authenticity markers such as low tartaric acid in pure pomegranate juice and presence of galacturonic and quinic acids in apple and blueberry blends were demonstrated. Wine profiles reflected fermentation acids (lactic, succinic) and grape acids (tartaric, malic) in characteristic ratios.

Advantages and Practical Applications of the Method

• High sensitivity for low UV‐absorbing acids without derivatization
• Minimal sample preparation and rapid throughput
• Wide dynamic range for multiple acids in a single run
• Robust authenticity testing and quality monitoring in beverage industry

Future Trends and Applications

Advances may include coupling with mass spectrometry for structural confirmation, further miniaturization and automation for on‐line process monitoring, rapid screening kits for field testing, and expansion to other food and environmental matrices.

Conclusion

The validated IC method using the AS11‐HC‐4 µm column and suppressed conductivity detection enables high‐resolution, sensitive and reproducible determination of organic acids in fruit juices and wines, supporting quality control and authenticity verification.

Reference

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