oa Agrochemophysica - Polyphenols, ascorbic acid and related enzyme activities associated with black heart in cayenne pineapple fruit

Volume 9, Issue 1
  • ISSN : 0302-7112



The phenolic acids p-coumaric, caffeic, ferulic and sinapic acids were tentatively identified from pineapple fruit, each possibly as a cis -and trans-isomer and according to IR spectra both in the ester form. Black heart fruitlets gave an increased concentration of each phenol except sinapic acid, compared with healthy fruitlets. Although ascorbic acid was lower in black heart fruitlets no ascorbic acid oxidase could be detected. Polyphenol oxidase activity was, however, higher in black heart fruitlets. Peroxidase activity had no apparent connection with black heart. It appears that exposure of the fruits to low winter temperatures, while on the plants, is responsible for cell disturbance, resulting in an accumulation of phenolic substances. Initially ascorbic acid may counter the oxidation of the phenols, but as the ascorbic acid concentration decreases the oxidation of phenols, through polyphenol oxidase, increases and browning occurs.

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