Effects of vacuum and pressure infiltration of calcium chloride and storage temperature on the incidence of bitter pit and low temperature breakdown of apples

Post-harvest treatment of apples with calcium chloride markedly reduced bitter pit and breakdown in several cultivars during three seasons in Australia and New Zealand. Infiltration of calcium chloride at pressures above or below atmospheric pressure improved the control over that obtained by simple immersion of the fruit in the calcium chloride solution, and was effective in the absence of the usual field sprays of calcium nitrate. These new treatments retained much of their effectiveness when the fruit were afterwards rinsed with water to reduce the risk of injury to the fruit or the grading equipment. The treatments were effective whether the fruit had open or closed calyces, but there were problems of excessive uptake and internal damage with some fruit having an open calyx. Commercial development of the process for closed calyx varieties such as Cox's Orange Pippin or Granny Smith is in progress. For the 3–4 month period required for export, the use of a lower temperature (0° instead of 3°C) improved the control of bitter pit, and a post-harvest calcium treatment reduced the incidence of low temperature breakdown.