Whey permeate analysis with NIRS

Importance of the Topic

Whey permeate is a major co-product of whey protein powder manufacturing, rich in lactose, minerals and phosphates. Its sweet, mild flavor makes it valuable in bakery and confectionery applications. Accurate, high-throughput monitoring of whey permeate composition is essential to maintain product quality and to optimize downstream processing.

Study Objectives and Overview

This application note investigates the use of near-infrared spectroscopy (NIRS) for rapid, nondestructive analysis of key quality parameters in whey permeate. The goal is to develop robust calibration models for simultaneous prediction of protein, lactose, moisture, ash, phosphate and pH, enabling real-time or at-line quality control in dairy operations.

Methodology

A total of 158 whey permeate samples were analyzed. Spectra were acquired in reflectance mode over 1000–2250 nm. Preprocessing steps included baseline correction and scatter removal, followed by wavelength selection to enhance model performance. Calibration models were built using multivariate regression. Model validation employed an independent external set comprising 25 % of samples. Reference values were determined according to ISO methods for each analyte.

Instrumentation

Measurements were performed on a Metrohm NIR Analyzer equipped with a small cup accessory. Spectral acquisition and chemometric model development were carried out using Metrohm’s proprietary software, facilitating straightforward data processing and prediction workflows.

Key Results and Discussion

All analytes exhibited strong correlation between NIR predictions and laboratory reference data. Correlation coefficients (R2) for protein, moisture, ash, phosphate and pH exceeded 0.80, with standard error of prediction (SEP) values demonstrating routine-analysis precision. Lactose prediction showed moderate performance (R2 ≈ 0.69), suggesting further calibration may be required for this component.

Benefits and Practical Applications

NIRS offers multiple advantages for whey permeate monitoring:

• Rapid, chemical-free analysis without sample preparation.
• Simultaneous quantification of multiple quality parameters.
• High throughput suitable for at-line or offline quality control.
• Reduced operational costs and waste generation compared to wet chemistry.

Future Trends and Opportunities

Emerging developments may further enhance NIR-based dairy analytics:

• Integration with process lines for real-time control and automation.
• Advanced chemometric techniques for improved calibration transfer.
• Miniaturized, portable NIR devices for on-site measurements.
• Data integration with Industry 4.0 platforms for predictive process management.

Conclusion

This study confirms that NIRS is a viable, efficient tool for comprehensive quality assessment of whey permeate. The developed models enable rapid decision-making in dairy production, supporting yield optimization and product consistency.

Reference

• ISO 22662:2024 Milk and milk products – Determination of lactose content by high-performance liquid chromatography
• ISO 8968-1:2014 Milk and milk products — Determination of nitrogen content (Kjeldahl method)
• ISO 5537:2023 Dried milk and dried milk products — Determination of moisture content by loss on drying
• ISO/DIS 9877 Milk and milk products — Determination of ash content by incineration