Bitter pit

Bitter pit can already be present at harvest. But it can also develop later in storage. It shows as dotted dark corky spots, which occur on the skin or under the skin in the flesh, or both. The spots do indeed have a bitter taste. The cells in the spots are dead and turn brownish-black. Spots can be more located towards the calyx end of the apple. This disorder is often related to a lack of calcium in the fruit, and solutions may be found in the pre-harvest stage.