SUPERFICIAL SCALD IN JONAGOLD AS AFFECTED BY HARVEST DATE AND STORAGE CONDITIONS

The effects of harvest date and storage conditions at 1°C on the amount of superficial scald (%scald) after 6 months of storage were studied in Jonagold apples collected from eight different orchards classified according to past occurrence of scald. Hexane extract of detached fruit peel was prepared to determine, at harvest and after removal from storage, the concentration of -farnesene and trienes, and the optical density at 205 nm (OD-205) as an estimate of total antioxidant activity in the peel. After storage at 3% O² + 1% CO² (High Oxygen Low Carbon Dioxide, HOLC) followed by 3 weeks of shelf life at 20°C %scald - averaged for the different harvest dates - was 23% after 3 weeks of shelf life at 20°C. At 1.5% O₂ + 1% CO₂ (LOLC) and 3% O₂ + 5% CO₂ (HOHC) %scald was 2% and 6% respectively, while at 1.5% O₂ + 5%CO₂ (LOHC) no scald was observed. This shows that in Jonagold both O₂ and CO₂ affect the occurrence of scald. At HOLC %scald was significantly higher in early harvested apples compared to apples from a normal harvest date of pick 1 (spot picking, 39% and 13% scald at 3 and 11 October) and also compared to an early and a normal harvest date of pick 2 (15% and 23.5% scald at 10 and 17 October). Fruits harvested at 3 October (early pick 1) had lower OD-205 values compared to fruits harvested at 11 October (normal pick 1) while in fruits stored at 1.5% O₂ OD-205 values were higher and trienes concentrations were lower compared to storage at 3%O₂. -farnesene concentrations were not influenced by harvest date or storage condition. Trienes concentrations at removal from storage were positively correlated with % scald after one week of shelf life (r=0.81) in early pick 1 at HOLC. -Farnesene concentrations at removal from storage were positively correlated with %scald after 3 weeks of shelf life (r=0.85). Correlations between % scald after storage and levels of -farnesene, trienes and of OD-205 values at harvest were low.