Advancing Milk Powder Authentication with Raman Spectroscopy and Chemometrics

In a recent study from Shanghai University, lead author and scientist Bing Niu and colleagues demonstrated the utility of a new method for quantifying and identifying animal-origin milk powders (1). The findings, published in the Journal of Dairy Science, help improve our knowledge of the chemical composition of milk powders and demonstrate that Raman spectroscopy, when combined with chemometrics, can help identify adulterants in these food products.

Milk contains many vital nutrients, which is why it is a popular commodity globally (2). Unfortunately, its popularity has given rise to the increased use of various adulterants, which may help preserve milk longer, but have negative consequences for human health. Scientists and food producers have uncovered benzoic acid, salicylic acid, nitrates, sulfates, and other substances in milk. Some of these adulterants has been linked in health issues such as asthma, pneumonia, nausea, gastroenteritis, heart problems, and allergic reactions (2). Benzoic acid, in particularly, is one of the most common adulterants found in milk and other beverages because it helps preserve and extend its shelf life (2).

Whole milk powder | Image Credit: © Viktor - stock.adobe.com

The same issue has arisen in milk powders. Traditional approaches have primarily focused on identifying common contaminants such as starch, soybean powder, and illegal additives (1). However, limited research has tackled the complex task of differentiating nonbovine milk powders, such as camel, mare, and donkey milk powders, from more common goat and cow milk powders. By leveraging Raman spectroscopy and advanced chemometric models, the researchers achieved improved accuracy in detecting adulteration and distinguishing between milk powders from various animal sources (1).

This study is different from previous work because of its use of the MultiClass Classifier model. The research team used this to conduct qualitative analysis of milk powders. For quantitative analysis, the researchers used partial least squares regression (PLSR) and support vector machine regression (SVR) (1).

The MultiClass Classifier model proved to be effective. It achieved over 93% accuracy, with sensitivity and specificity exceeding 80% (1). The area under the curve (AUC) values were 0.9357 and 0.9478, which demonstrated that the model could differentiate between milk powders of various animal origins (1).

PLSR and SVR models demonstrated robust linear correlations, with coefficients of determination (R²) above 0.95 (1). Errors remained minimal, with root mean square error (RMSE) and mean relative error (MRE) both below 0.2 (1). This enabled precise quantification of adulteration involving camel, mare, and donkey milk powders.

Overall knowledge of the chemical composition of milk powders is still limited (3). By optimizing the models with feature selection and advanced processing methods, the researchers demonstrated the ability to accurately detect adulterants not only in specialty milk powders but also in common powdered substitutes such as soy and rice powders (1). Using Raman spectroscopy helped the researchers conduct their analysis without destroying the samples.

The capability to reliably identify and quantify adulteration in specialty milk powders ensures greater transparency and trust in product labeling (1). Moreover, the methods developed in this study can be adapted for broader applications, including the detection of adulterants in other powdered food products.

As the dairy industry continues to expand globally, the demand for high-quality, authentic products will only grow. This work demonstrates the importance of integrating spectroscopic techniques like Raman spectroscopy into food safety practices, ensuring that consumers receive products that meet the highest standards of quality and authenticity.

References

1. Zhang, X.; Yang, Q.; Gu, S.; et al. Rapid Identification Method of Milk Powder from Different Animals based on Raman Spectroscopy. J. Dairy Sci. 2025, 108 (1), 136–151. DOI: 10.3168/jds.2024-25309
2. Choudary, M.; Sharma, N. Milk Adulterants: Serious Impact on Human Health. J. Med. Evid. 2024, 5 (2), 124–128. DOI: 10.4103/JME.JME_145_23
3. Pugliese, A.; Cabassi, G.; Chiavaro, E.; et al. Physical Characterization of Whole and Skim Dried Milk Powders. J. Food Sci. Technol. 2017, 54 (11), 3433–3442. DOI: 10.1007/s13197-017-2795-1