Occurrence of cellobiose residues directly linked to galacturonic acid in pectic polysaccharides

► The pectic polysaccharides from plum, pear, and commercial citrus pectin were submitted to a selective hydrolysis with endo-polygalacturonase. ► The low molecular weight oligosaccharides (<1 kDa) were analysed by mass spectrometry and methylation analysis. ► It was observed the occurrence of single Glc and Glc-Glc residues directly linked to GalA. ► The Glc disaccharides were β-1,4-linked.