Quantitative and Morphological Studies on Starch of Apple Fruit during Development

The starch content of apple fruit (Males domestica Borkh ‘Jonagold’) during development varied depending on the location in the flesh. The most prominent feature was the higher starch content and lower decrease rate in the outer part of the flesh than in the inner and middle part of the flesh. Light microscopy observations coincided well with the analytical data. Examination with a scanning electron microscope showed that starch granules were spherical in shape with a smooth surface and were composed of several fragments. The distribution pattern of the granule size in every part of the flesh did not reveal any significant changes during fruit development. Furthermore, at the late stage of development, the magnitude of the decrease of the mean diameter of starch granules could not account for the decrease of the starch content. These facts indicate that starch degradation of ‘Jonagold’ fruit starts mainly from inside of the granules.