Characterisation of Cell Wall Pectins by near Infrared Spectroscopy

Pectins are complex polysaccharides found in the primary cell wall of most plants, gluing adjacent cells together. Structurally the main pectic polysaccharide is primarily a linear polymer of (1,4)-linked α-D-galacturonic acid which may be partially methyl esterified. This backbone is interrupted by (1,2)-linked a-D-rhamnopyranose which serves as anchoring points for the attachment of lateral neutral oligosaccharides containing mainly D-galactopyranoses and Larabinofuranoses. Several studies have shown that pectic substances play an important role in regulating the firmness of processed vegetables. The chemical composition of pectins (i.e., degree of esterification, distribution of rhamnopyranoses and amount of specific neutral sugars) and the interrelation with other cell wall polysaccharides, determine the firmness of the fresh and processed plant tissue. The aim of this study was to investigate the potential of Fourier-Transform Near Infrared Spectroscopy (FT-NIR) and chemometrics as a reliable and fast method for the determination of the chemical composition and the degree of esterification (DE) of cell wall pectins. Material and methods