Apple juice pectic substances

Apple juice pectic substances are characterised by a high content of galacturonic acids (75·6%), a high degree of esterification (83), a low content of neutral sugars (0·109 moles/mole of galacturonate residues) and a high molecular weight ($\text{M}{}_{\mathrm{v}}\text{= 95 000}$). Degradation by heat (β-elimination) and by endopolygalacturonase showed that the pectic macromolecules consist of long homogalacturonan regions (92% of total galacturonides) and of ‘hairy’ regions in which neutral sugars form long or short side-chains.