Chemometric methods using mid-FTIR spectroscopy were developed in order to reduce the time of study of melamine and cyanuric acid in infant formulas. Chemometric models were constructed using the algorithms Partial Least Squares (PLS1, PLS2) and Principal Component Regression (PCR) in order to correlate the IR signal with the levels of melamine or cyanuric acid in the infant formula samples. Results showed that the best correlations were obtained using PLS1 (R2: 0.9998, SEC: 0.0793, and SEP: 0.5545 for melamine and R2: 0.9997, SEC: 0.1074, and SEP: 0.5021 for cyanuric acid). Also, the SIMCA model was studied to distinguish between adulterated formulas and nonadulterated samples, giving optimum discrimination and good interclass distances between samples. Results showed that chemometric models demonstrated a good predictive ability of melamine and cyanuric acid concentrations in infant formulas, showing that this is a rapid and accurate technique to be used in the identification and quantification of these adulterants in infant formulas.

Empty microcapsules, originally designed as carriers of bioactive peptides, were prepared by the combined method of a double-emulsion complex with coacervation spray drying and were subjected to an in-vitro digestion process, producing peptides from the whey protein contained in the microcapsule walls. The inhibitory effect of the enzyme dipeptidyl peptidase-4 (DPP-4) and modulation of the insulin receptor of hydrolyzed microcapsules were evaluated. The hydrolysate of the microcapsules was subjected to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) analysis, showing the presence of low-molecular-weight peptidic compounds, which apparently were responsible for the DPP-4 inhibitory effect. Fluorescence analysis showed that the effect of the hydrolyzed microcapsules on the insulin receptor was 40% that of insulin. The inhibition of DPP-4 was 54.7%. This work demonstrated that empty microcapsules initially designed as carriers of functional peptides also have the capability to inhibit DPP-4 and modulate insulin receptors by themselves.