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

Significance of the topic

Dairy powders serve as essential functional ingredients in many food formulations, with their performance and labeling tied directly to accurate knowledge of protein, lactose, fat, and moisture content. Traditional wet-chemical methods for quantifying these components are reliable but often slow, labor intensive, and costly. Vibrational spectroscopy, particularly mid-infrared (mid-IR) with attenuated total reflectance (ATR), has emerged as a rapid, non-destructive approach to characterize complex powder matrices in seconds without extensive sample preparation.

Objectives and overview of the study

This application note demonstrates the effective use of the Agilent Cary 630 ATR-FTIR analyzer for the quality assurance and quality control (QA/QC) of various dairy protein powders. The primary objective was to establish a spectral library of common milk proteins, then test the instrument’s capability to differentiate and authenticate products such as α-lactalbumin, β-lactoglobulin, whey protein isolate (WPI), and whey protein concentrate (WPC).

Used instrumentation

• Agilent Cary 630 ATR-FTIR analyzer (portable mid-IR spectrometer with diamond ATR crystal)
• MicroLab FTIR software spectral library builder and automated matching

Methodology

Samples of commercially obtained milk protein powders were directly applied to the diamond ATR crystal without any solvent extraction or chemical pretreatment. A pressure clamp ensured consistent contact between the powder and crystal surface. For each measurement, 64 co-added spectra were recorded over the 4000–650 cm⁻¹ range at 4 cm⁻¹ resolution, achieving a total acquisition time of approximately 30 seconds.

Main results and discussion

The built spectral library enabled rapid identification of unknown samples by matching their IR fingerprints against reference spectra. Key spectral differences were observed, for example, additional carbohydrate bands in WPC between 1300 and 900 cm⁻¹ corresponding to lactose. Proteins such as α-lactalbumin, β-lactoglobulin, and WPI exhibited distinct amide I and II bands that the software reliably distinguished. Automated matching correctly identified α-lactalbumin as an unknown sample, confirming the robustness of the approach.

Benefits and practical applications of the method

• Time savings: analysis completed in under one minute per sample
• Minimal sample preparation: no reagents or solvents required
• Portability: instrument suitable for dock-side, production line, or laboratory use
• Cost efficiency: reduced labor and consumables compared to traditional methods
• High specificity: clear spectral markers for proteins and carbohydrates

Future trends and potential applications

Continued integration of mid-IR spectroscopy with advanced chemometric tools will further enhance quantification accuracy for complex dairy formulations, including blends and fortified powders. Portable ATR-FTIR devices could be deployed in supply-chain checkpoints, remote facilities, and field-based quality surveys. Machine learning algorithms may extend library matching to detect adulterants or subtle batch-to-batch variations in real time.

Conclusion

The Agilent Cary 630 ATR-FTIR analyzer provides a rapid, accurate, and user-friendly solution for routine QA/QC of dairy powders. By leveraging a spectral library and automated matching, manufacturers can authenticate raw materials and monitor consistency with minimal training and without destructive testing.

References

• Li-Chan ECY, Griffiths PR, Chalmers JM, editors. Applications of Vibrational Spectroscopy in Food Science, Volumes 1 and 2. John Wiley & Sons; 2010.
• Li-Chan ECY, Ismail AA, Sedman J, Van de Voort FR. Vibrational Spectroscopy of Food and Food Products. In: Chalmers JM, Griffiths PR, editors. Handbook of Vibrational Spectroscopy, Vol. 5. John Wiley & Sons, Ltd; 2002. p. 3629–3662.
• Van de Voort FR, Sedman J, Ismail AA, Dwight S. Moving FTIR Spectroscopy into the Quality Control Laboratory. Part 1: Principles and Development. Lipid Technol. 1996;8(4):117–119.