Abstract: As a representative of non-melting-flesh peach, Wanhujing peach cultivar was used to investigate the degradation of cell wall polysaccharides in non-melting-flesh peach during its softening and the activities of related enzymes. During peach fruit ripening, CDTA-1 pectin content increased, and the contents of two kinds of Na2CO3 soluble pectin were decreased by 22.5% and 27.4% until the late stage. KOH soluble pectin content did not change significantly throughout the ripening process. The degradation of pectin main chains in CDTA and Na2CO3 and the loss of arabinosyl and galactosyl from pectin side chains in cellulosic polysaccharides mainly happened at the end of the ripening process. β-galactosidase was associated with the start-up of peach fruit softening. Polygalacturonase and Cx-Cellulase were important enzymes that contributed to the end of peach fruit softening. Na2CO3-1 pectin was an important factor affecting non-melting-flesh peach fruits softening. The degradation of KOH-1 and KOH-2 fractions may promote peach fruit softening. The fracture of pectin chain rich in galacturonic, as well as the degradation of neutral sugars such as arabinose and galactose in pectin, hemicellulos and cellulose, and a variety of polysaccharides degrading enzyme were likely to be important factors affecting non-melting-flesh peach fruit softening.

Key words: peach, ripening and softening, cell wall polysaccharides, monopolysaccharide composition