Incidence of bitter pit in relation to the calcium content of apples: Problems and paradoxes, a review

The problems of relating low fruit calcium concentrations in stored apples to the development of bitter pit lesions are reviewed. They include nomenclature, anomalous fruit analyses, variability in the susceptibility of apples to pitting and in the time and rate of pit development, effect of harvest date, accumulation of calcium in pitted tissue and the apparant translocation of calcium during storage from the core into zones of tissue most at risk. Recent evidence suggests that bitter pit lesions are induced by the removal of calcium from these outer zones to meet intermittent demands by the core tissue.