Loss of Firmness and Changes in Pectic Fractions during Ripening and Overripening of Sweet Cherry

Pectic fractions soluble in water, oxalate, or hydrochloric acid were prepared from an alcohol-insoluble residue of cherry (Prunus avium L., `Bigarreau Napoléon') tissue. Galacturonic acid and neutral sugar contents were measured during the ripening and overripening of fruit. Fruit firmness was also determined. The changes occurring during fruit development gave prominence to three physiological stages and suggested the progressive degradation of the middle lamella and primary cell wall. The firmness measurement was related to the equilibrium between the relative parts of these pectic fractions.