Textural property and cell wall metabolism of ‘Golden Bosc’ and ‘d’Anjou’ pears as influenced by oxygen regimes after long-term controlled atmosphere storage

Abstract

Controlled atmosphere (CA) allows long-term storage of European pears (Pyrus communis L.) without chemical treatment to deliver a natural melting (buttery and juicy) texture for consumers. However, the relationship between textural properties and cell wall metabolism as influenced by O2 regimes has not been comprehensively determined. In this study, ‘Golden Bosc’ and ‘d’Anjou’ pears were stored in 21 (air), 2, 1, or 0.5% O2 with < 0.5% CO2 for up to 8 and 10 months at −1.1 °C plus 7 d of ripening at 20 °C, respectively. Melting texture development in both cultivars showed high correlations with the level of water-soluble polyuronides (WSP) and activity of β-galactosidase (β-GAL). Also, activities of pectin methylesterase (PME) and α-arabinofuranosidase (α-ARF) were associated with softening in ‘Golden Bosc’ pears. Concentrations of CDTA-soluble polyuronides (CSP) and WSP + CSP + sodium carbonate-soluble polyuronides (SSP), as well as ethylene production showed positive correlations to melting texture in ‘d’Anjou’ pears. Reducing O2 concentrations from 21% to 2-–1% and 1–0.5% in ‘Golden Bosc’ and ‘d’Anjou’ pears allowed pears to develop a desirable eating texture during ripening for up to 8 and 10 months, respectively, with a commercially acceptable levels of postharvest disorders. Use of 1–0.5% O2 resulted in a melting texture in ‘Golden Bosc’ pears, but fruit developed more core browning when ripe. These results indicate that O2 regimes regulate textural qualities by influencing WSP level and β-GAL activity.