Evaluation of human breastmilk adulteration by combining Fourier transform infrared spectroscopy and partial least square modeling

Abstract

A two-step chemometric procedure was developed on the attenuated total reflection-Fourier transform infrared data of human breastmilk to detect adulteration by water or cow milk. The samples, collected from a Milk Bank, were analyzed before and after adulteration with whole, skimmed, semi-skimmed cow milk and water. A preliminary clustering via principal component analysis distinguished three classes: pure milk, milk adulterated with water, and milk adulterated with cow milk. A first partial least square-discriminant analysis (PLS-DA) classification model was built and then applied on new samples to identify the specific adulterants. The external validation on this model reached 100% of the correct identification of pure milk and 90% of the type of adulterants. In the following step, four PLS calibration models were built to quantify the amount of the adulterant detected in the classification analysis. The prediction performance of these models on new samples showed satisfactory parameters with root mean square error of prediction and percentage relative error lower than 1.38% and 3.31%, respectively.

Keywords: adulteration; attenuated total reflection‐Fourier transform infrared; human breastmilk; partial least square; principal component analysis.

Figure 1

Sample‐making scheme

Figure 2

Multistep chemometric procedure

Figure 3

Spectral data: (a) FTIR spectra for pure human breastmilk (BM), whole cow milk (CM), semi‐skimmed cow milk (SSCM), and skimmed cow milk (SCM) samples; (b) Loadings plot for PCs from 1 to 4 resulted from PCA

Figure 4

3D score plot (PC1, PC2, and PC4) by PCA (a) and PLS‐DA regression (b)