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.