Improving the corn to ethanol fermentation process with near-infrared spectroscopy (NIRS)

Importance of the Topic

Bioethanol produced from corn starch plays a critical role in meeting renewable fuel mandates and reducing greenhouse gas emissions. Reliable monitoring of fermentation parameters ensures optimal yeast performance, product yield, and process economics. Traditional laboratory analyses introduce delays that limit plant throughput and profitability.

Objectives and Study Overview

This study evaluates near-infrared spectroscopy (NIRS) as a rapid, non-destructive alternative to multiple routine lab methods. It aims to demonstrate reduction of analysis time, improve real-time process control, and increase annual production capacity by up to 10%. A cloud-based workflow for remote calibration updates is also presented.

Methodology and Instrumentation

Samples of corn mash during fermentation were analyzed by both primary lab techniques and NIRS. Primary methods included refractometry for dissolved solids, pH meter, infrared balance for non-volatiles, HPLC and ion chromatography for ethanol, sugars, glycerol and organic acids, and Karl Fischer titration for moisture. NIRS spectra were acquired on a Metrohm DS2500 Solid Analyzer using Vision Air software. A set of pre-calibrations was deployed locally and models were refined via secure cloud connection to a Vision Air Server.

Key Results and Discussion

NIRS reduced total measurement time per sample from approximately 60 minutes to under five minutes, achieving a 90% time saving. Faster data allowed detection of lactic acid and glycerol deviations within minutes rather than hours, enabling timely interventions. Compared to 62–65 hours required with traditional analyses, NIRS-guided fermentations reached endpoint in 56 hours. This six-hour saving translates to 13 additional batches annually, increasing throughput by 10%.

Benefits and Practical Applications

• Single-instrument analysis replaces six lab methods, reducing operating costs and labor.
• Improved process oversight with near-real-time feedback and actionable control decisions.
• Cloud-based model management accelerates deployment and continuous calibration without in-person support.

Future Trends and Opportunities

Expansion of NIRS to monitor byproducts such as dried grains, corn oil, and water content in ethanol is feasible. Integration with AI-driven analytics and predictive maintenance can further optimize yield. Industry-wide adoption of cloud-based NIR models promises standardization and continuous improvement across plants.

Conclusion

NIRS offers a rapid, economic, and operator-friendly approach to fermentation monitoring, cutting analysis time by 90% and boosting plant capacity by 10%. Cloud-enabled calibration streamlines method deployment and adaptation, making NIRS an essential tool for modern ethanol production.

Instrumentation Used

• Metrohm DS2500 Solid Analyzer with Vision Air software
• Refractometer
• pH meter
• Infrared balance
• HPLC and ion chromatography systems
• Karl Fischer titrator

References

1. Essential Energy: 2021 Ethanol Industry Outlook. Renewable Fuels Association, Washington, DC.
2. Determining the Cost of Producing Ethanol from Corn Starch and Lignocellulosic Feedstocks. NREL, Golden, CO, 2000.
3. Metrohm AG. Simplifying Quality Control Using Near-Infrared Spectroscopy. WP-037EN, 2018.
4. Ingledew WM. The Biochemistry of Alcohol Production. In The Alcohol Textbook, 2nd Ed., Nottingham University Press, 1995.