CA Induced Internal Browning in `Pink Lady' Apples

Abstract

The internal browning (IB) disorder of `Pink Lady' apples is the manifestation of some undefined physiological conditions of the fruit at harvest, which predispose them to damage during CA storage. Internal browning problems generally occur intermittently and in unpredictable patterns. This type of disorder has the potential for widespread economic impacts. The optimum storage conditions and underlying physiological factors remain understood. In Fall 2002, `Pink Lady' apples were harvested in Stockton, Calif., at two maturities, then placed into CA storage. After storage, the percentage of fruit with IB increased with greater CO2 and with lower O2 concentrations. The incidence of IB injury was greater in fruit from the second harvest, but there was not a great difference in incidence between 2 and 6 months of storage. In Fall 2003, `Pink Lady' apples were harvested on the same orchard at three maturities and placed into CA storage. In all three experiments, fruit were stored in either air, 2% O2 + 1% CO2, or 2% O2 + 3% CO2 at 0.5 °C. In the first experiment, three harvest maturities were placed into storage immediately after harvest. For the second experiment, apples from harvest 2 were treated prior to fruit storage with 1ppm 1-MCP for 24 hours, 2200 ppm DPA, or were untreated. In the third experiment fruit from harvest 3 were placed into CA storage after 0, 2, or 4 weeks in air at 0.5 °C. No IB was observed for any of the three maturities after 0.5 and 1 month storage. After 2 months IB injury was present in 4.8% of the fruit stored in 1% CO2 and 4.6% stored in 3% CO2 from harvest one. A lower percentage of IB was observed in harvest two. Harvest three presented 0% and 2.6% of IB in 1% and 3%CO2 respectively. The effect of 1-MCP,DPA and delayed CA on IB will be discussed.