Quality Control of fermentation broths

Quality Control of Fermentation Broths Using Near-Infrared Spectroscopy

Significance of the Topic

The fermentation process is a cornerstone of biopharmaceutical manufacturing, producing small molecules and protein-based APIs. Monitoring critical quality parameters—such as pH, microbial load, sugar concentrations, and potency—is essential to ensure yield, safety, and consistency. Traditional assays are time-consuming and reagent-intensive, creating bottlenecks in process optimization and scale-up.

Objectives and Study Overview

This application note investigates the use of Vis-NIR spectroscopy for rapid, non-destructive, multiparameter analysis of fermentation broths. The study aims to develop and validate calibration models predicting pH, bacterial concentration, glucose, reducing sugars, and potency within one minute per sample.

Methodology and Instrumentation

Samples from various fermentation stages were measured in reflectance mode on the Metrohm DS2500 Solid Analyzer without sample preparation. Spectral data (400–2500 nm) were collected and processed using Vision Air Complete software to build Partial Least Squares (PLS) regression models.

Used Instrumentation

• DS2500 Solid Analyzer (Metrohm no. 2.922.0010)
• NIRS transflection vessel, optically flat (6.7401.000)
• Mini sample cup holder for DS2500 (6.7430.040)
• Vision Air 2.0 Complete spectroscopy software (6.6072.208)

Main Results and Discussion

• pH prediction achieved R2 = 0.65 with an external validation error of 0.10 pH units.
• Bacterial concentration model yielded R2 = 0.71, SEP ~5 CFU/mL.
• Glucose quantification reached R2 = 0.92, validation error ~0.86% w/w.
• Reducing sugars model exhibited R2 = 0.99, validation error ~1.24% w/w.
• Potency models using UV-Vis and HPLC+PCR reference methods showed R2 = 0.91 and 0.92, respectively, with validation errors below 2,100 u/mL.

High correlation between NIR predictions and reference assays demonstrates the robustness and reliability of the models. The rapid acquisition and minimal sample handling reduce measurement variability.

Benefits and Practical Applications

• Measurement time reduced from minutes or hours per assay to under one minute.
• No reagents or consumables required, lowering operational costs.
• Non-destructive analysis facilitates downstream or parallel testing.
• Suitable for integration in production lines and QA/QC labs.

Future Trends and Potential Applications

With advances in chemometric algorithms and sensor miniaturization, inline NIR monitoring will become more widespread. Real-time feedback control of fermentation parameters can enhance process intensification and adaptive manufacturing. Integration with digital twins and Industry 4.0 platforms will further streamline bioprocess optimization.

Conclusion

Vis-NIR spectroscopy on the DS2500 platform enables rapid, accurate, and cost-effective monitoring of key fermentation quality attributes. The approach offers substantial time savings and operational benefits over conventional wet methods, supporting more agile and data-driven biopharmaceutical production.

Reference

• No external literature references were provided in the source document.