Determination of Moisture in Flour

Significance of the Topic

Precise measurement of moisture in flour is essential for food quality control, ingredient standardization, and compliance with regulatory standards. Moisture content influences texture, shelf life, microbial stability, and yield calculations for both producers and manufacturers in the baking and grain industries.

Objectives and Study Overview

This application note demonstrates the use of the TGM800 thermogravimetric analyzer for moisture determination in various flour samples. The aim was to evaluate fixed-time and mass-constancy drying methods, assess reproducibility across sample types (barley, wheat, rice, corn), and compare results obtained with different crucible sizes and sample masses.

Methodology and Applied Instrumentation

The analysis employed a loss-on-drying technique in a controlled atmosphere. Key method parameters:

• Instrument: LECO TGM800 thermogravimetric analyzer
• Temperature program: ramp from 25°C to 130°C at 10°C/min, hold for 60 min; optional ramp at 20°C/min
• Atmosphere: convective flow rate of 4.0 L/min
• Sample mass: ~1.0 g to ~2.0 g
• Crucible options: aluminum foil crucibles (1.5 in and 2.4 in) mounted on a carousel

Sample preparation involved grinding flour to pass a 40-mesh screen. Methods followed AOAC Official Method 925.10.

Main Results and Discussion

Across three flour types, moisture contents consistently fell between 7.6 % and 8.0 %, with relative standard deviations typically under 0.1 %. Fixed-time drying in 2.4 in crucibles yielded average moisture values of 7.89 % (s=0.03 %) for barley and 7.67 % (s=0.02 %) for wheat. Smaller crucibles produced similar results within analytical uncertainty. The mass-constancy method confirmed these findings with an average of 7.85 % moisture (s=0.05 %) for barley.

Benefits and Practical Applications

The TGM800 delivers rapid, accurate moisture readings essential for routine quality control in milling and baking operations. Its programmable temperature profiles, high reproducibility, and compatibility with standard reference materials enable reliable assessment of flour batches, aiding in process optimization and compliance with food safety regulations.

Future Trends and Applications

Emerging developments in thermogravimetry may include integration of advanced sensors for real-time moisture monitoring and automated sample handling to increase throughput. Coupling with chemometric analysis could enhance discrimination of flour varieties and detection of adulteration.

Conclusion

The LECO TGM800 thermogravimetric analyzer provides a robust, validated method for determining moisture content in flour. It supports both fixed-time and mass-constancy protocols, delivering consistent results across sample types and crucible configurations, thereby ensuring reliable quality control for the food industry.

References

AOAC Official Method 925.10. Solids (Total) and Moisture in Flour.
LECO Corporation. TGM800 Instruction Manual.
LECO Corporation. Application Note: Determination of Moisture in Flour.