Fermentation Processes Monitoring Using a Nexera™ Dual Injection System

Significance of the Topic

Fermentation monitoring in industrial and food applications requires measuring organic acids and sugars to control process efficiency and product quality.
Simultaneous analysis of these compound classes can accelerate data acquisition and improve laboratory workflows.

Objectives and Overview

This study demonstrates the use of a dual injection HPLC system to perform parallel analyses of organic acids and sugars from fermentation samples using a single instrument.
The article details method integration on the Nexera SIL-40 autosampler, describing flow channels, detection modes, and sample handling.

Methodology and Instrumentation Used

• Dual Injection System: Nexera SIL-40 series autosampler configured to split injection into two flow channels.
• Organic Acid Analysis: Ion-exclusion Shim-pack Fast-OA column with post-column pH buffering and electrical conductivity detection at 40 °C.
• Sugar Analysis: Ligand exchange Shim-pack SCR-101C column with refractive index detection at 80 °C.
• Mobile Phases: Aqueous p-toluenesulfonic acid buffer for acids; water for sugars.
• Instrument Integration: Two column ovens (CTO-40S), solvent delivery units, detectors and data acquisition in a unified data file.

Main Results and Discussion

• Chromatographic Performance: Baseline separation of five organic acids (citric, malic, lactic, formic, acetic) and four sugars (lactose, glucose, mannose, fructose) with retention times reproducible (RSD < 0.06 %).
• Linearity: Calibration ranges of 10–1000 mg/L for acids and 10–2000 mg/L for sugars yielded correlation coefficients R2 ≥ 0.9998.
• Carryover: Low carryover values (< 0.01 %) confirmed minimal cross-contamination between injections.
• Sample Recovery: Spiked yogurt samples showed recoveries of 94.6–101.8 % for acids and 100.9–107.7 % for sugars, indicating robust quantitation.
• Fermentation Time Course: Yogurt fermentation at 40 °C monitored over 8.5 hours revealed lactose consumption and lactic acid accumulation, illustrating process tracking capability.

Benefits and Practical Applications of the Method

• High Throughput: Parallel analysis reduces total runtime and increases sample throughput.
• Instrument Efficiency: Single-system approach eliminates the need for multiple HPLC setups.
• Data Traceability: Integrated data files maintain sample identity across analyses.
• Versatility: Applicable to various fermentation media and measuring additional compound classes with minimal reconfiguration.

Future Trends and Potential Applications

Emerging developments may include expansion to volatile and amino acid analysis by integrating MS detection and further automation of sample preparation.
Real-time process analytical technology (PAT) could leverage dual injection designs for inline monitoring and feedback control in bioprocesses.
Enhanced column chemistries and multi-detector arrangements are expected to support broader compound coverage and faster separations.

Conclusion

The dual injection HPLC approach on the Nexera platform successfully enables simultaneous quantitation of organic acids and sugars in fermentation samples.
Method validation confirmed robust linearity, precision, carryover control, and sample recovery.
This integrated workflow streamlines analytical operations, offering benefits for research and industrial quality control in fermentation processes.

Reference

• Shimadzu Technical Report C190-E237. High-Speed Analysis of Organic Acids Using Shim-pack Fast-OA and pH-Buffered Electrical Conductivity Detection.