Modifications of cell wall pectin in chilling-injured 'Friar' plum fruit subjected to intermediate storage temperatures

- 'Friar' plums suffer severer chilling injury in storage at 5 and 15 °C than 0 °C.
- Chilling injury is associated with the modification of cell wall pectin in plums.
- The loss of neutral sugars and depolymerisation of SSP in chilled plum is reduced.
- The detachment and degradation of liner chains in SSP in chilled plum is enhanced.
- The differential modification of SSP nanostructure may result in texture collapse.

'Friar' plum (Prunus salicina Lindl.) fruit were stored at low (0 °C), intermediate (5 and 15 °C) and ambient temperature (25 °C). Flesh translucency was evidenced as the main chilling injury (CI) symptom and the CI developed rapidly at 5 and 15 °C but suppressed at 0 °C. Modifications of cell wall pectin in 'Friar' plums were investigated during storage. Sodium carbonate-soluble pectin (SSP) was found to be predominant in the fruit but it decreased more rapidly at 5 and 15 °C than 0 °C. Nevertheless, SSP possessed abundant galactose, arabinose and rhamnose at 5 and 15 °C. Nanostructural observations indicated that the detachment and degradation of linear backbone chains in SSP molecules were enhanced at 5 and 15 °C. Therefore, the development of CI of 'Friar' plums at intermediate temperatures was associated with the modifications of SSP in the cell wall pectin of the fruit subjected to chilling stress.