Sorbitol Metabolism, the Climacteric, and Watercore in Apples

Extraction and assay of sorbitol dehydrogenase (SDH) throughout fruit maturation of 3 apple ( Malus domestica Borkh.) cultivars, watercore-resistant ‘Golden Delicious,’ occasionally susceptible ‘McIntosh’, and normally susceptible ‘Starkrimson,’ showed no relationship between susceptibility to watercore and extractable enzyme activity. There was, however, a relationship between increased SDH activity and onset of the climacteric as measured by ethylene and CO 2 evolution, suggesting that SDH, like certain other enzymes, increases during maturation.