Marco Antônio Moreira Furtado

Quantification of whey in fluid milk using confocal Raman microscopy and artificial neural network

In this work, we assessed the use of confocal Raman microscopy and artificial neural network as a practical method to assess and quantify adulteration of fluid milk by addition of whey. Milk samples with added whey (from 0 to 100%) were prepared, simulating different levels of fraudulent adulteration. All analyses were carried out by direct inspection at the light microscope after depositing drops from each sample on a microscope slide and drying them at room temperature. No pre- or posttreatment (e.g., sample preparation or spectral correction) was required in the analyses. Quantitative determination of adulteration was performed through a feed-forward artificial neural network (ANN). Different ANN configurations were evaluated based on their coefficient of determination (R2) and root mean square error values, which were criteria for selecting the best predictor model. In the selected model, we observed that data from both training and validation subsets presented R2>99.99%, indicating that the combination of confocal Raman microscopy and ANN is a rapid, simple, and efficient method to quantify milk adulteration by whey. Because sample preparation and postprocessing of spectra were not required, the method has potential applications in health surveillance and food quality monitoring.

Microfluidic chip electrophoresis investigation of major milk proteins: study of buffer effects and quantitative approaching

The separation and quantification of major milk proteins are fundamental in dairy research. Therefore, accurate and rapid methods are profoundly important. The microfluidic chip technique is faster, and uses considerably fewer chemicals and materials than traditional techniques. The objective of this study was to improve experimental methods for separating and quantifying major milk proteins using the microfluidic chip technique. Deionized water, a total protein solubilization buffer (TPS buffer) and a separating milk protein buffer (SEP buffer) were used for the treatment of milk samples and their effects were evaluated. The results showed an excellent separation for whey proteins with α-lactalbumin migrating first, followed by β-lactoglobulin in the presence of both buffers. However, better results for major casein separation were obtained when SEP buffer was added. The order of the migration time was: β-casein first, followed by αs-casein and κ-casein. The quantitative analysis showed significant differences among the percentages of protein fractions from both buffers. The results of microfluidic chip technology using the SEP buffer solution were comparable to those obtained by SDS-PAGE for these proteins and to the data reported in the literature.