The furanoside linkage of sugars is much more acid labile than the pyranoside bond and is readily hydrolyzed by mild acid treatment. Exceptions occur among some of the 3,6-anhydrohexosides in which the furanose structure is more stable than the pyranose. Some arabans are autohydrolyzed by boiling in water; the acidity being provided by associated pectic acid. Arabinofuranose residues attached to complex polysaccharides may be preferentially cleaved by heating the polysaccharide in dilute acid solution. The method described in this article describes the preferential release of L- arabinose from a wheat flour water soluble pentoglycan.