QA/QC of dairy powders using the Agilent Cary 630 ATR-FTIR analyzer

Importance of the Topic

Ensuring the quality and consistency of dairy powders is critical for both food manufacturers and regulatory authorities. Conventional analyses of proteins, fats and lactose rely on solvent extraction and chromatography, which are accurate but slow, labor-intensive and costly. Mid-infrared spectroscopy with an ATR accessory enables rapid, reagent-free measurements that can be performed at the receiving dock, in production areas or QA/QC laboratories, supporting real-time decision making and safeguarding supply chain integrity.

Objectives and Study Overview

The main goal was to develop a fast, reliable approach to authenticate and discriminate multiple dairy protein powders, focusing on uniquely identifying α-lactalbumin against β-lactoglobulin, whey protein isolate (WPI), whey protein concentrate (WPC) and casein derivatives. The study explores how the Agilent Cary 630 ATR-FTIR analyzer and MicroLab FTIR software can establish a spectral library and classify unknown samples within seconds.

Instrumentation Used

• Agilent Cary 630 ATR-FTIR analyzer equipped with a diamond ATR crystal and pressure clamp.
• Agilent MicroLab FTIR software for spectral library creation and automated matching.
• Protein powder samples: α-lactalbumin, β-lactoglobulin, glycomacropeptide, milk protein concentrate, WPI, WPC, caseins and caseinates from various suppliers.

Methodology

Sample spectra were recorded by placing a small amount of powder onto the ATR crystal and applying consistent pressure. Sixty-four co-added scans were collected between 4000 and 650 cm⁻¹ at 4 cm⁻¹ resolution in about 30 seconds. A reference library of known spectra was built using representative batches, and new ‘unknown’ spectra were matched automatically to the database.

Key Results and Discussion

Spectral differences are evident in the fingerprint region (1300–900 cm⁻¹), where lactose bands distinguish WPC from pure protein powders. Despite similar overall spectral patterns among α-lactalbumin, β-lactoglobulin and WPI, the automated library matching correctly classified unknown α-lactalbumin samples, demonstrating robust discrimination capability. The entire process from sample placement to identification takes under a minute.

Benefits and Practical Applications

Rapid, minimal-prep ATR-FTIR analysis reduces turnaround time, lowers operating costs and minimizes training requirements. The compact, portable Cary 630 system is ideal for on-site authentication of dairy powders at receiving docks, in-line monitoring in production or routine QA/QC checks in laboratories.

Future Trends and Opportunities

• Integrating chemometric models for quantitative prediction of protein, fat and lactose content.
• Embedding ATR-FTIR sensors into production lines for continuous monitoring.
• Expanding spectral libraries to cover a broader range of dairy and non-dairy ingredients.
• Combining FTIR data with other techniques (NIR, Raman) for multi-modal quality assessment.

Conclusion

The Agilent Cary 630 ATR-FTIR analyzer paired with automated library software offers a fast, cost-effective solution for the authentication and quality control of dairy powders. Its portability and ease of use make it a valuable tool for ensuring raw material consistency and protecting product integrity in various stages of the supply chain.

References

1. Li-Chan, E. C. Y., Griffiths, P. R. & Chalmers, J. M. (2010). Applications of Vibrational Spectroscopy in Food Science, Volumes 1 and 2. John Wiley & Sons.
2. Li-Chan, E. C. Y., Ismail, A. A., Sedman, J. & Van de Voort, F. R. (2002). Vibrational Spectroscopy of Food and Food Products. In J. M. Chalmers & P. R. Griffiths (Eds.), Handbook of Vibrational Spectroscopy, Vol. 5, 3629–3662. John Wiley & Sons.
3. Van de Voort, F. R., Sedman, J., Ismail, A. A. & Dwight, S. (1996). Moving FTIR Spectroscopy into the Quality Control Laboratory. 1. Principles and Development. Lipid Technology, 8(4), 117–119.