Elevated storage temperatures for plums

For both Sapphire and Laetitia plums storage under 2°C caused chilling injury in the fruit because the treatment caused low levels of the highly unsaturated phospholipid fatty acid linolenic acid (C18:3n3) and low antioxidant levels (specifically ascorbic acid and glutathione).

Elevated storage temperatures are not recommended for Sapphire plums irrespective of the harvest maturity or the area the fruit is sourced from as it may develop chilling injury (area- dependent) or overripeness (maturity dependent). The lower levels of chilling injury in Sapphire fruit sampled from Robertson was firstly due to higher levels of antioxidants (HAA and L-AA) in fruit from this area and, it seems, to a lesser extent, due to higher levels of linolenic acid in fruit from this area compared to fruit sourced from Simondium.

The 5°C treatments and the 7.5°C treatment compared well to the DT-regime for Laetitia fruit due to high L-AA levels in these treatments, but then the fruit must be harvested in the upper end of the maturity window to prevent decay development (5°C treatments) and overripeness (7.5°C treatment). No internal defects developed when the Laetitia fruit was treated with Smartfresh^TM and stored under -0.5°C, irrespective of harvest maturity or area.