Determination of Nitrogen/Protein in Meat and Plant-Based Meat Alternatives

Significance of the Topic

The accurate quantification of protein content in meat and plant-based products is essential for nutritional assessment, regulatory compliance and economic evaluation. Traditional wet-chemical approaches like Kjeldahl are time-consuming and involve hazardous reagents. The combustion (Dumas) method offers a rapid and safer alternative for high-throughput laboratories.

Objectives and Study Overview

This application note demonstrates the use of the LECO FP828 nitrogen determinator to measure nitrogen and calculate protein in various meat and meat alternative samples. Key goals include validating method precision, comparing different sample dose loops and carrier gases, and confirming compliance with a modified AOAC 992.15 protocol.

Methodology and Instrumentation

Instrumentation

• LECO FP828 with vertical quartz furnace and thermoelectric moisture removal
• Thermal conductivity detector for N₂ measurement
• Carrier gases: Helium (highest sensitivity) or Argon (cost-effective alternative)
• Aliquot dose loops: 10 cm3 (optimal precision) and 3 cm3 (extended reagent life)

Sample Preparation and Analysis Workflow

• Prepare homogeneous samples following AOAC 983.18 for meat and certified reference materials.
• Condition instrument with reference replicates, determine blank levels, then calibrate using LECO LCRM materials.
• Analyze ~0.25 g of sample in tin foil cups; perform replicate determinations.
• Apply a multiplier of 6.25 to convert measured nitrogen to protein.

Results and Discussion

Analysis of ham, corned beef, turkey, roast beef and a plant-based veggie burger under different conditions showed consistent nitrogen and protein values with relative standard deviations generally below 0.5%. Helium carrier gas provided slightly higher sensitivity and lower detection limits, while Argon offered cost advantages with acceptable performance. Both 10 cm3 and 3 cm3 loops produced comparable accuracy, with the smaller loop extending reagent lifetime.

Benefits and Practical Applications

• Rapid analysis: complete combustion and gas measurement in around three minutes.
• Reduced sample preparation and elimination of hazardous chemicals.
• High precision and reproducibility suitable for QA/QC in food production.
• Flexible carrier gas options to balance sensitivity and operational cost.

Future Trends and Potential Applications

The adoption of automated combustion analysers is expanding into diverse food matrices and environmental samples. Future enhancements may include integration with advanced detectors, miniaturized sample loops for microscale analysis and real-time data analytics driven by AI for dynamic quality control and regulatory reporting.

Conclusion

The LECO FP828 offers a robust and efficient platform for nitrogen/protein determination in meat and plant-based products. Its automated combustion approach streamlines workflows while maintaining high accuracy and precision, making it a valuable tool for laboratories seeking to improve throughput and safety.

Reference

• AOAC 992.15 – Crude Protein in Meat and Meat Products (Combustion Method)
• AOAC 983.18 – Meat and Meat Products Sample Preparation