Compositional changes in cell wall polyuronides and enzyme activities associated with melting/mealy textural property during ripening following long-term storage of 'Cornice' and 'd'Anjou' pears

摘要

Irregular ripening is a major deterrent for the purchase of European pears. Cell wall polyuronides and related modifying enzymes were investigated in two European winter pears, 'Cornice' and 'd'Anjou', during ripening at 20 degrees C following 5 and 8 months of storage at 1.1 degrees C. Both pear cultivars developed a melting (buttery-juicy) texture and higher water-soluble polyuronides (WSP) in flesh tissue after 5 months, but the pears' texture quality decreased and a mealy (coarse-dry) texture presented in 'Cornice' pear after long-term storage. Activities of pectin methylesterase (PME) and alpha-arabinofuranosidase (alpha-ARF) in 'Cornice' pears was positively correlated with texture development, whereas in 'd'Anjou' pears polygalacturonase (PG), PME, cellulase (CEL), and figalactosidase (beta-GAL) were more highly correlated with texture. 1-MCP reduced pear ripening by inhibiting ethylene production and the activities of cell wall-modifying enzymes, maintaining higher antioxidants, and alleviating membrane lipid peroxidation. These results indicated melting texture developed in European pears as a result of the synthesis of WSP and increase of PME activity during pear fruit softening.