Characterisation and enzymatic hydrolysis of cell-wall polysaccharides from different tissue zones of apple

Abstract

Cell-wall polysaccharides from different tissue zones, namely epidermis, the outer parenchyma, the parenchyma of the carpels zone, the carpels and the core line, were isolated as alcohol-insoluble solids (AIS), extracted with cyclohexane-diaminotetraacetic acid, then hot dilute hydrochloric acid, and analysed, then purified by ion-exchange chromatography. In both zones of parenchyma, the cell-wall material represented about 80% of the total cell-wall material from the whole fruit. The pectins from the outer parenchyma accounted for 70% of the total, whereas the carpels zone contained a large proportion of cellulose and hemicelluloses. However, there was no change in galacturonic acid concentration. The enzymatic solubilisation of tissues or AIS was higher in the parenchyma zones than in the others. Nevertheless, the depolymerisation of the soluble pectins from parenchyma zones with an endopolygalacturonase required the action of pectin methylesterase. The depolymerisation of pectins from the other zones, however, did not.