Quality attributes and cell wall properties of strawberries (Fragaria annanassa Duch.) under calcium chloride treatment

► Strawberry firmness was not significantly affected by CaCl2 treatment. ► Strawberry softening due to modifications of pectin chains. ► CaCl2 treatment slowed the breakdown of pectin chains from nanoscale analysis. ► A schematic model of strawberry pectin degradation during storage was proposed. Effects of CaCl2 (0%, 1% and 4%) treatment on quality attributes and cell wall pectins of strawberry fruits stored at 4°C for 15d were investigated. Strawberry firmness was not significantly affected by CaCl2 treatment. Compared to the other groups, the 1% CaCl2 group had better quality attributes, including decay rate, weight loss and soluble solids content. The treatment with 4% CaCl2 inhibited weight loss but caused phytotoxicity. During storage, the chain widths and lengths of water-soluble pectin (WSP), chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) decreased. Strawberry softening seemed to be due to modifications of CSP and SSP, especially the side chains. CaCl2 treatment significantly slowed the breakdown of CSP and SSP chains by strengthening the ionic crosslinkages among these pectin molecules. These results illustrate the fundamental CaCl2 effects and will help improve the application of CaCl2 to postharvest fruits.