Post-harvest changes in Mangifera indica mesocarp cell walls and cytoplasmic polysaccharides

During ripening, mango mesocarp cell walls undergo degradation with the net loss of arabinose, galactose and galacturonic acid. Hot water fractions of the cell walls from unripe fruits were rich in galactose and arabinose and contained only 7% galacturonic acid in comparison with those from unripe fruits which contained 90% uronic acid: little change occurred in the alkali-soluble (hemicellulose) fraction during ripening. The ripening-associated changes in the cold water-soluble cytoplasmic polysaccharides in the mesocarp were also examined. As the mesocarp softened these increased in amount and bound uronic acid increased three-fold. Gel-filtration and ion-exchange chromatography were used to examine these cytoplasmic polysaccharides. Their average M r decreased on ripening and most of the fractions were complex with respect to monosaccharide composition. However, polysaccharides which are essentially an arabinoxylan and a galacturonan appeared to be present in the unripe and ripe tissue, respectively.