PPO Activity and Polyphenol Content are not Limiting Factors During Brown Core Development in Pears (Pyrus communis L. cv. Conference)

Abstract

Brown core is a disorder in pears that is frequently observed in the Conference cultivar. The brown colour is the result of an enzymatic oxidation of polyphenol substances to o -quinones, a reaction catalysed by polyphenoloxidases (PPO). In a later stage pears can form cavities in and nearby the core. The goal of our research was to understand and predict the development of core browning. Pears from orchards in Spain and The Netherlands were compared to observe climatic influences on the development of brown core. PPO activity and total polyphenol content are not affected by harvest date, storage atmosphere and orchard, and both do not seem to be limiting during development of brown core. An observed decrease of tyrosinase activity might be the consequence of the decreased viability of brown tissue. We hypothesize that core browning is induced by decompartmentation of intracellular membrane structures.