CHARACTERIZATION AND ENZYMATIC-HYDROLYSIS OF CELL-WALL POLYSACCHARIDES FROM DIFFERENT TISSUE ZONES OF APPLE

Cell-wall polysaccharides from different tissue zones, namely epidermi s, the outer parenchyma, the parenchyma of the carpels zone, the carpe ls and the core line, were isolated as alcohol-insoluble solids (AIS), extracted with cyclohexane-diaminotetraacetic acid, then hot dilute h ydrochloric acid, and analysed, then purified by ion-exchange chromato graphy. In both zones of parenchyma, the cell-wall material represente d about 80% of the total cell-wall material from the whole fruit. The pectins from the outer parenchyma accounted for 70% of the total, wher eas the carpels zone contained a large proportion of cellulose and hem icelluloses. However, there was no change in galacturonic acid concent ration. The enzymatic solubilisation of tissues or AIS was higher in t he parenchyma zones than in the others. Nevertheless, the depolymerisa tion of the soluble pectins from parenchyma zones with an endopolygala cturonase required the action of pectin methylesterase. The depolymeri sation of pectins from the other zones, however, did not.