Cell wall modification during development of mealy texture in the stony-hard peach “Odoroki” treated with propylene

The melting peach cultivar “Akatsuki” [Prunus persica L. Batsh] develops melting texture during ripening, but the stony-hard peach cultivar “Odoroki”, softens and develops a mealy texture when treated with propylene. Cell wall polysaccharides were fractionated as 1,2-diaminocyclohexanetetraacetic acid (CDTA)-, Na2CO3-, NaOH-soluble fractions, or the cellulosic residues that remained after solvent extraction. Size-exclusion chromatography of the CDTA-soluble fraction revealed a limited depolymerization of polyuronides in mealy “Odoroki” fruit, accompanying a lower level of endo-polygalacturonase (endo-PG) and a higher level of exo-PG activities compared to melting “Akatsuki” fruit. “Akatsuki” fruit showed increases in the arabinose, galactose and rhamnose contents in the CDTA-soluble fraction. These neutral sugars decreased in the Na2CO3-soluble and cellulosic residue fractions during ripening. Similar changes were observed for neutral sugars other than arabinose during softening in mealy “Odoroki” fruit. Arabinose content did not increase in the CDTA-soluble fraction of “Odoroki” fruit; however, arabinose content decreased in the Na2CO3-soluble fraction and in the cellulosic residue as observed for “Akatsuki” fruit. A significant increase in α-l-arabinofuranosidase activity, about 10 times higher than for “Akatsuki” fruit, was observed in propylene-treated mealy “Odoroki” fruit. Differences in ripening-associated metabolic changes in the cell walls of these peach cultivars seem to be related to their differences in texture.