Glycosidic linkages of swede cell walls and their residues recovered from the terminal ileum of the pig

Abstract

The glycosidic linkage pattern of unfractionated swede cell walls was determined by methylation analysis. The main linkages in descending order of concentration were: (1----4)-linked glucose, (1----4)-linked xylose, terminal galactose, (1----4)-linked mannose, terminal arabinose and (1----2)-linked rhamnose. The major branch points were to the O-2 or O-3 atoms of xylose, O-4 of rhamnose and O-6 of glucose. The subsequent degradation of swede cell walls by passage through the small intestine of the pig was studied by quantitative methylation analysis of material recovered from animals cannulated 150 mm before the ileo-caecal junction. In addition to a substantial loss of uronic acid and phenolic material, the proportions of the different glycosidic linkages recovered from the digesta varied greatly from those of the parent material. Pectic polysaccharides had apparent digestibilities in the range of 0.60-0.75 while those of hemicellulosic components varied between 0.15 and 0.57. Glucose units linked 1----4 (with an apparent digestibility of 0.24) accounted for the greatest weight loss of neutral sugars from the cell wall, followed by terminal galactose, terminal arabinose and 2-linked arabinose.