Ascorbic acid mapping to study core breakdown development in 'Conference' pears

Core breakdown is a physiological disorder, characterised by discolouration of the inner core tissue, that can develop during storage of pears under certain controlled atmosphere (CA) conditions. Recent research suggested a relation between this storage disorder and ascorbic acid concentrations. Postharvest changes of ascorbic acid concentrations and spatial distribution have been investigated. Loss of ascorbic acid during delayed CA (cooling period of 3 weeks in air before CA storage) was observed, but further losses during subsequent CA storage were minimal. Browning-inducing CA storage conditions resulted in a more than 4-fold faster decrease in ascorbic acid concentration. A threshold of 0.37 mg 100 g(-1) FW ascorbic acid was determined below which the incidence of internal browning was higher than 50%. Ascorbic acid maps show a strong asymmetrical distribution and illustrate that most brown tissue was located in the contour line of 0.4 mg 100 g(-1) FW, which supports the 0.37 mg 100 g-1 FW threshold value. The occurrence of sound spots in the brown tissue zone corresponded with higher ascorbic acid concentrations, and could be associated to the protective capability of ascorbic acid. (C) 2003 Elsevier B.V. All rights reserved.