Supercritical fluid extraction (SFE) is becoming a routine treatment in food processing.  Recent work has shown that SFE treatment of milk powder provides greater selectivity in removal of triacylglycerols and saturated fatty acids from milk than conventional skimming, while leaving more nutritive lipids (e.g., phospholipids) largely in place.  However, little is known about the effects of supercritical CO<sub>2</sub> on the other biomolecules of milk, particularly the protein fraction, whose composition and structure are crucial both to the nutritional and physicochemical properties of milk products.  We have used dispersive Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy to characterize the chemical changes occurring in milk powders upon various SFE treatment regimes.  In addition to confirming the previously-observed selectivity of SFE for saturated lipid extraction, we find evidence that SFE produces some structural changes in proteins, specifically α-helix to β-sheet conversion, consistent with irreversible aggregation.  By using principal component analysis (PCA) on our vibrational spectra, we are furthermore able to track the distinct chemical changes occurring upon SFE treatment under various lengths of time and pressures via the PCA score plots.  These results suggest Raman spectroscopy is a simple and robust method for characterizing milk products subject to SFE treatment, and that when used in combination with PCA may be useful for optimizing and standardizing SFE treatments for obtaining the desired chemical properties of the treated milk products.<br/>

Vibrational spectroscopy and multivariate data analysis for elucidation and classification of compositional changes in milk subject to Supercritical Fluid Extraction (SFE)

253rd National Meeting (2017)

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