|Harnly, James - Jim|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2013
Publication Date: 9/16/2013
Citation: Botros, L., Jablonski, J., Chang, C., Bergana, M., Wehking, P., Harnly, J.M. 2013. Exploring authentic skim milk powder variance for the development of nontargeted adulterant detection methods using NIR spectroscopy and chemometrics. Journal of Agricultural and Food Chemistry. 61:9810-9818. Interpretive Summary: The skim milk powder (SMP) adulteration project was aimed at developing methods for detection of adulteration. Although SMP is the target material of this project, it is anticipated that the philosophy of approaches to methods will serve as a model for any food or botanical supplement. Detection of an adulterant is dependent on an accurate knowledge of the composition and spectrum of authentic materials. In this paper, we examined the near-infrared spectra of 41 SMP and non-fat dry milk (NFDM) samples. We determined the variance between manufacturers, between locations, between sample types (SMP or NFDM), between samples, and between days of analyses. This data provides the foundation for developing a wide variety of methods for detecting adulterants.
Technical Abstract: A multinational collaborative team led by the US Pharmacopeial Convention is currently investigating the potential of NIR spectroscopy for nontargeted detection of adulterants in skim milk powder. The development of a compendial method is challenged by the range of authentic or nonadulterated skim milk powders available worldwide. This paper investigates the sources of variance in 41 authentic bovine skim milk powders and nonfat dry milks as detected by NIR diffuse reflectance spectroscopy and chemometrics. Exploratory analysis by principal component analysis and varimax factor rotation revealed significant variance in authentic samples and highlighted outliers from a single manufacturer. Spectral preprocessing and outlier removal methods reduced ambient and measurement sources of variance, most likely linked to changes in moisture together with sampling, preparation, and presentation factors. Results indicate that significant chemical variance exists in different skim milk powders that will likely affect the performance of adulterant detection methods by NIR spectroscopy.