Linking lenticel discolouration of mango (<i>Mangifera indica</i>L.) fruit to reversed-phase HPLC profiles of phenolic compounds

Abstract

SummaryDiscolouration of mango lenticels intensifies progressively from a slight red halo during the initial development of the condition, to a blackened area surrounding each lenticel. Initial aqueous methanol extracts of discoloured tissue were further fractionated into phenolic groups and analysed by means of reversed-phase high performance liquid chromatography. Discernable shifts in phenolic profiles correlated with the colour changes in affected lenticels. After staining with Vanillin-HCl, fluorescence microscopy of fixed material revealed the locations of, and changes in the different forms of phenolics associated with various degrees of discolouration. The results confirmed that the compounds responsible for the discolouration of lenticels were simpler flavonones rather than more complex anthocyanidins. The chromatographic results correlated with previous observations using transmission electron microscopy, which indicated that the accumulation of cell wall-bound phenolics did not result from vacuolar collapse or membrane disintegration.