COMPARISON OF THE PHENOLIC PROFILES IN THE PEEL OF SCALDED AND NON SCALDED ‘GRANNY SMITH’ AND ‘CROFTON’ APPLES

Abstract

Superficial scald is a physiological storage disorder of apples, which is characterised by browning of the skin. Scald is thought to be due to an uncontrolled polyphenol oxidase (PPO) system oxidising the vacuolar phenolics. Phenolics have been implicated in numerous physiological processes during the storage of fruit. Therefore, it is important to understand the role of phenolics in long term storage and the development of superficial scald. In these experiments, phenolics were identified and quantified from the peel of preclimacteric 'Granny Smith' and 'Crofton' apples during air storage at 0°C. The phenolics from both scald affected and apparently healthy green peel tissue from the same control 'Granny Smith' apples were extracted, separated and quantified with diode array HPLC. Analysis of scalded and non scalded peel tissue from the same 'Granny Smith' apples showed there was a significant decline in the concentration of all the phenolics, particularly the flavonols, in scalded tissue. A new phenolic compound, benzoyl-β-D-glucose, not previously identified in apples, was detected in the scalded peel tissue. These changes in phenolic profile may have significant implications concerning the role of phenolics in the storage physiology and the development of scald in apples.