Flour analysis by near-infrared spectroscopy (NIRS)

Significance of the Topic

Near-infrared spectroscopy (NIRS) enables rapid, reagent-free analysis of key flour quality parameters, supporting efficient milling operations and ensuring product consistency.

Goals and Overview

This study evaluates the feasibility of using a Metrohm OMNIS NIR Analyzer Solid to predict moisture, protein, ash, and rheological properties in various flour types within seconds, aiming to streamline quality control workflows.

Methodology

• A total of 237 flour samples (wheat, spelt, others) analyzed in diffuse reflection mode with a rotating sample cup.
• Spectral data automatically averaged to enhance model robustness.
• Reference analyses performed according to AOAC methods: moisture (953.10), protein (2001.11), and ash (923.03).

Used Instrumentation

• Metrohm OMNIS NIR Analyzer Solid for solid and viscous samples.
• Large OMNIS NIR 100 mm holder and sample cup enabling multi‐position measurements.
• OMNIS Software with Quant Development license for calibration model creation.

Main Results and Discussion

• Moisture: R2=0.827, SEC=0.47%, SECV=0.48%.
• Protein: R2=0.789, SEC=1.89%, SECV=2.68%.
• Ash: R2=0.929, SEC=0.221%, SECV=0.231%.
• Gluten: 15-35% range, SEC=1.39%, SECV=1.40%, R2CV=0.918.
• Starch: 15-26% range, SEC=0.86%, SECV=0.97%, R2CV=0.755.
• Baking strength: 36-444 range, SEC=29.94, SECV=30.75, R2CV=0.919.
• Elasticity index: 30-65 range, SEC=2.32, SECV=2.67, R2CV=0.906.
• Tenacity: 43-382 range, SEC=20.00, SECV=21.69, R2CV=0.910.

Benefits and Practical Applications

• Chemical-free and minimal sample preparation reduces operational costs.
• Rapid analysis (<10 seconds) facilitates at-line or laboratory quality checks.
• Improves milling yield and product consistency through real-time monitoring.
• Accessible workflow requiring minimal user training.

Future Trends and Opportunities

Integration of NIRS into production lines for real-time monitoring, development of robust calibrations across diverse flour types, application of machine learning for enhanced predictive models, and convergence with automation and IoT platforms for comprehensive process control.

Conclusion

NIR spectroscopy with the Metrohm OMNIS platform delivers fast, accurate, and cost-effective multi-parameter flour analysis, enabling continuous quality assurance and process optimization in milling and baking operations.

References

1. AOAC 953.10: Official Method for Moisture in Flour.
2. AOAC 2001.11: Dumas Combustion Method for Protein.
3. AOAC 923.03: Method for Ash Content in Flour.