Production area and harvest date influence superficial scald incidence and ultra-structure of 'Suli' pear skin during long term storage

The effect of production area and harvest date on the superficial scald incidence, ultra-structure of the pericarp, core browning, and related physical qualities of ‘Suli’ pears during storage period at 0 °C were investigated. ‘Suli’ fruits were harvested at Taigu and Linyi in Shanxi province of China over five different dates and then stored at 0±0.5 °C with 85-90% relative humidity for 120 or 200 days. Superficial scald was detected after 120 and 200 days of storage. Harvest date and production area significantly affected the incidence of superficial scald and the quality of ‘Suli’ fruits. Earlier harvest time was associated with increased incidence of superficial scald. Fruits picked at Linyi developed more severe superficial scald than fruits harvested at Taigu. Scanning electron microscope (SEM) revealed that the cuticle and wax layer of fruits from Taigu were thicker than those from Linyi after storage. The surface of earlier harvested fruits had less wax and more extensive cracking, lower pectin content, and damaged skin organization structure. The incidence of superficial scald in ‘Suli’ pears is dependent on the ultra-structure of these superficial layers, and differences may be driven by harvest date and location.