Monitoring Organic Acids during Fermentation with Shim-pack Fast-OA High-Speed Organic Acid Analytical Column

Significance of the Topic

Organic acids are essential both as sensory components in food and as intermediates in pharmaceutical and chemical industries. Accurate and rapid analysis of these acids during fermentation processes enables real-time control of microbial activity, improving product quality and process efficiency. Shortening analysis time without compromising selectivity or sensitivity is critical for applications in biotechnology, food science, and environmental monitoring.

Objectives and Study Overview

This study demonstrates a fast, reliable method for monitoring five key organic acids—phosphoric, citric, malic, lactic, and acetic acid—during yogurt fermentation. By employing a high-speed ion-exclusion liquid chromatography column (Shim-pack Fast-OA) coupled with post-column pH-buffered conductivity detection, the aim was to achieve complete separation of target analytes in under 12 minutes and validate the method for standard mixtures and real samples.

Methodology and Instrumentation

The core separation was performed on two Shim-pack Fast-OA 2 columns connected in series (100 mm × 7.8 mm I.D.), with a guard column (10 mm × 4.0 mm I.D.) upstream. The mobile phase consisted of 5 mmol/L p-toluenesulfonic acid at a flow rate of 0.8 mL/min, and column temperature was maintained at 30 °C. Detection was carried out by a conductivity detector. For sample pretreatment, yogurt drinks were mixed with the acidic mobile phase and chloroform to remove proteins and lipids, centrifuged, and the supernatant filtered through a 0.2 μm membrane prior to injection.

Applied Instrumentation

• Shim-pack Fast-OA 2 analytical columns (in series) with guard column
• Conductivity detector (CDD-10Avp)
• HPLC system for high-speed ion-exclusion separation
• Centrifuge and membrane filtration for sample cleanup

Key Results and Discussion

Separation of the five standard acids was completed within 10 minutes, with elution order correlating to pKa values. Calibration curves over 10–1000 mg/L showed excellent linearity (r2 > 0.9999) and reproducibility (RSD < 1.5%). Recovery tests in spiked yogurt yielded rates between 96% and 118%. Time-course monitoring during home yogurt fermentation revealed a significant increase in lactic acid after 3.5 hours, demonstrating the method’s capability for dynamic process tracking.

Benefits and Practical Applications

This method offers:

• Rapid analysis time (12 minutes per run) for high-throughput screening
• High selectivity for organic acids via ion-exclusion and pH-buffered conductivity detection
• Robust quantification with minimal sample preparation
• Real-time monitoring potential for fermentation control in food and biotech industries

Future Trends and Potential Applications

Advances in column technology and detector sensitivity may further reduce run times and improve limits of detection. Integration with automated sampling systems could enable fully automated bioreactor monitoring. The approach can be extended to other fermentation products, environmental water analysis, and metabolic profiling in microbiome research.

Conclusion

The Shim-pack Fast-OA ion-exclusion HPLC method with conductivity detection provides a fast, sensitive, and reproducible platform for monitoring key organic acids during fermentation. Its speed and minimal sample preparation make it highly suitable for routine quality control and real-time process management.

References

No literature references were provided in the original document.