Effects of temperature and cultivar on nanostructural changes of water-soluble pectin and chelate-soluble pectin in peaches

► Characterized nanostructure of fruit pectins by atomic force microscopy. ► Changes of chain widths of different pectins showed similar trends. ► Proposed a schematic model of peach pectin degradation in widths during storage. ► Degradation of pectin widths might be independent of their chemical contents. Two cultivars of peaches (‘Cangfangzaosheng’ and ‘Songsenzaosheng’) were stored at 2°C, 8°C and 15°C for maximum of 41 days. The nanostructural changes of water-soluble pectin (WSP) and chelate-soluble pectin (CSP) of all cultivars were analyzed qualitatively and quantitatively by atomic force microscopy (AFM). The results show that long linear single pectin chains of peach were detached and the percentage of small width chains increased during storage. This phenomenon was also found with increased storage temperature. Moreover, the widths of pectin molecules of both peach cultivars were similar and very regular. Combined with previous reports, the results indicate that nanostructural degradations of pectin widths might be independent of their chemical content changes.