Composition, Physico-chemical Properties and Enzymatic Degradation of Fibres Prepared from Different Tissues of Apple

Abstract

Apple fibres from the tissue of three zones, namely epidermis, parenchyma and carpels zones, were prepared as nonoxidized and freeze-dried water-insoluble solid (WIS), oxidized and freeze-dried WIS, oxidized and oven-dried WIS, and nonoxidized and solvent-dried alcohol-insoluble solid. The yield and composition of the fibres, the characteristics of their soluble fraction, the enzymatic solubilization of the fibres and their hydration capacities were analysed. Oxidation led to a decrease in the amount of buffer-soluble pectin and to an increase of its hydrodynamic volume. It also decreased susceptibility to enzymatic solubilization and hydration capacities. Oven-drying, simulating industrial conditions, produced an important decrease of swelling capacity and enzymatic hydrolysis. Preparation of alcohol-insoluble solid led to higher fibre yield in all tissue zones but did not alter their properties. © 1997 Academic Press Limited.