FTIR spectroscopy as a tool for the analysis of olive pulp cell-wall polysaccharide extracts

The sequential extraction of olive pulp cell-wall material (CWM) and its subsequent fractionation by ethanol precipitation and anion-exchange chromatography gave a wide range of cell-wall polysaccharide fractions, characterised by sugar analysis. Several multivariate procedures, such as principal component analysis (PCA), trimmed object projections (TOP), canonical correlation analysis (CCA), and partial least squares regression (PLS), were applied to their FTIR spectra, in the region between 1200 and 850 cm−1. The combination of these chemometric techniques along with the chemical information allowed the type of polymers present to be distinguished: pectic polysaccharides rich in uronic acid, pectic polysaccharides rich in arabinose, arabinose-rich glycoproteins, xyloglucans, and glucuronoxylans. It was also possible to highlight the most important and characteristic wavenumbers for each type of polymer present. A calibration model for the quantification of xylose residues of the hemicellulosic polysaccharides was proposed. The high diversity of samples used and their characteristic features allowed models to be obtained, using a very expeditious methodology, that represent a realistic description of the olive pulp cell-wall polymers.