Contaminant Analysis in Food Manufacturing Process by EDX and FTIR

Significance of the Topic

Contamination by foreign matter during food manufacturing poses serious safety, quality, and regulatory challenges. Rapid and accurate identification of such contaminants is essential to prevent product recalls, protect consumer health, and maintain production efficiency. Combining energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR) offers complementary elemental and molecular insights, enabling robust characterization of both metallic and organic residues encountered in food processing environments.

Objectives and Study Overview

This study demonstrates an integrated EDX-FTIR approach for the systematic analysis of five representative contaminant samples recovered from a food production line. Key aims include:

• Evaluating sample pretreatment strategies ranging from no processing to chemical rinses.
• Assessing the combined analytical power of EDX and FTIR for precise identification of metals, polymers, and adhered food residues.
• Establishing a practical workflow that balances speed, sensitivity, and non-destructive analysis.

Methodology

Five contaminant types—metallic fragments and non-metallic particles—were collected and subjected to the following protocol:

1. Initial EDX measurement without pretreatment to obtain elemental composition.
2. FTIR-ATR scan on untreated particles to detect organic functional groups and polymer types.
3. Sequential rinsing steps (acetone, acid mixtures, or purified water) to remove surface residues, followed by repeat FTIR and EDX analyses when necessary.

Special attention was given to sample–prism contact during ATR measurement for small or uneven particles to ensure reliable spectra.

Instrumentation

Key analytical instruments and settings included:

• EDX-7000 energy dispersive X-ray spectrometer (Rh target, vacuum atmosphere, 1 mm collimator, 15/50 kV tube voltage, SDD detector).
• IRTracer-100 FTIR spectrometer with AIM-8800 ATR accessory (8 cm⁻¹ resolution, 40 scans, MCT detector, square-triangle apodization).

Main Results and Discussion

The combined EDX-FTIR workflow yielded clear identifications for all five samples:

• Sample 1: Tin-plated steel fragment. EDX detected Fe and Sn signal peaks; FTIR showed no significant organic peaks.
• Sample 2: Nickel plating peel. Dominant Ni peak via EDX; FTIR inconclusive for organics.
• Sample 3: Polyethylene particle with food residues. EDX indicated light elements (C, O, K, Ca); FTIR spectra matched polyethylene with attached oils, fats, and polysaccharides.
• Sample 4: Hard black polypropylene fragment coated with food deposits. EDX revealed Ca and organic elements; FTIR before rinsing identified lactic acid and vitamins on resin surface, while acetone rinse exposed polypropylene signature.
• Sample 5: Epoxy-coated copper film carrying Zn and Se residues. EDX pre-rinsing showed Cu, Zn, Se; post-rinsing only residual Se. FTIR confirmed epoxy resin matrix both before and after acid treatment.

This tandem strategy improved confidence in material classification, particularly for composite or resin-coated contaminants.

Benefits and Practical Applications

The synergy of EDX and FTIR delivers:

• Fast, largely non-destructive screening of both inorganic and organic contaminants.
• Minimal sample preparation, with optional rinsing for surface cleaning and enhanced molecular detection.
• Versatility across a range of particle sizes, shapes, and compositions typical in food process environments.

These features support quality control, HACCP compliance, and root-cause investigations in food manufacturing.

Future Trends and Potential Applications

Emerging directions include:

• Integration with automated sample handling and imaging systems for high-throughput screening.
• Coupling with chemometric software for spectral deconvolution and database matching.
• Miniaturized, portable EDX-FTIR modules for in-line or on-site contamination monitoring.
• Advanced ATR accessories to accommodate sub-millimeter particles and uneven surfaces.

Conclusion

The combined EDX and FTIR approach provides a robust, efficient route to characterize diverse foreign particles in food production. By leveraging complementary elemental and molecular data, analysts can achieve precise contaminant identification with minimal preparation. This workflow enhances laboratory throughput and supports proactive quality assurance in the food industry.

References

• Shimadzu Application News No. A452.
• Izumi Nakai (Editor), A Practical Guide for X-ray Fluorescence Analysis, Asakura Publishing, 2006.