Content and chemical composition of epicuticular wax of ‘Navelina’ Oranges and ‘Satsuma’ Mandarins as Related to Rindstaining of Fruit

Abstract

AbstractChanges in the content and chemical composition of epicuticular wax of susceptible and non‐susceptible ‘Navelina’ orange and non‐susceptible ‘ Satsuma’ mandarin fruits to rindstaining, growing in the area of Valencia (Spain), were studied. The epicuticular wax content of the susceptible Navelina fruits increases with ripening from 30 μg cm−2 in July to 110 μg cm−2 in January. The epicuticular wax content of the non‐susceptible Navelina fruits was similar to that of the susceptible ones. The epicuticular wax content of the Satsuma mandarin fruits was lower than that of Navelina orange fruits; it changed from 20 μg cm−2 in July to 40 μg cm−2 in January. In this study, no correlation between epicuticular wax content and susceptibility to rindstaining of the orange fruits was found. In general, alkanes, aldehydes and fatty acids are the major wax constituents, whereas the primary alcohols and the triterpenoids are the minor ones. The maximum incidence of rindstaining occurs at the end of October and the beginning of November, immediately after the major rate of increase of the fruit surface. Such an increase also concurs with the major hardening and facility of cracking of the wax layer.