Determination of Carbohydrates in Kombucha Using HPAE-PAD

Significance of the Topic

Accurate measurement of simple sugars in kombucha is essential for ensuring consistent product quality, correct nutritional labeling and understanding potential health impacts. Residual glucose, fructose and sucrose concentrations influence taste, fermentation dynamics and consumer safety, particularly for individuals monitoring blood sugar levels.

Objectives and Study Overview

The main goal was to develop a direct, accurate HPAE-PAD method for quantifying glucose, fructose and sucrose in kombucha. Three commercial kombucha samples were analyzed to evaluate method linearity, precision, accuracy and the impact of hardware modifications on dilution requirements.

Methodology

Samples were centrifuged at 6 500–7 500 g for 15 min, filtered through a 0.2 µm membrane and diluted 1:500. High-performance anion-exchange chromatography with pulsed amperometric detection was conducted using an isocratic hydroxide eluent: 100 mM KOH for column washing, 10 mM KOH for analysis. The flow rate was 0.5 mL/min, injection volume 10 µL and column temperature 30 °C.

Instrumentation Used

• Thermo Scientific Dionex ICS-5000+ system with EG Eluent Generator and vacuum degas option
• Dionex CarboPac PA20 analytical column (3 × 150 mm) with CR-ATC 500 trap
• Pulsed amperometric detector with gold on PTFE disposable electrode and 15 mil gasket
• Ag/AgCl reference electrode (pH) and 10 µL PEEK sample loop

Main Results and Discussion

Baseline separation of glucose, sucrose and fructose was achieved in 15 min with >5 min wash and re-equilibration. Calibration curves were linear over 0.2–50 mg/L (glucose), 10–100 mg/L (sucrose) and 0.2–100 mg/L (fructose) with r² ≥ 0.9992. Precision (RSD) for retention time was <0.1% and for peak area <4.1%. Spike recovery ranged from 80–126%. Increasing the electrochemical gasket thickness extended the linear range, enabling a uniform 500-fold dilution across samples.

Benefits and Practical Applications

• No chemical derivatization simplifies workflow and reduces analysis time
• High sensitivity and selectivity support accurate quality control in beverage production
• Extended linear range minimizes error from extensive dilutions
• Rapid, robust method suitable for routine monitoring of fermentation and final product

Future Trends and Applications

Advances may include automated online dilution systems, coupling HPAE-PAD with mass spectrometry for detailed carbohydrate profiling, application to a broader range of fermented beverages and integration with real-time quality monitoring in production lines.

Conclusion

The HPAE-PAD method with a Dionex CarboPac PA20 column and modified electrode spacer provides reliable, accurate determination of simple carbohydrates in kombucha. The hardware modification simplifies sample preparation and extends method flexibility, making it a practical tool for beverage analysis and quality assurance.