In the experiments referred to below, the relationships between bruising, fungal decay, heat treatment, and controlled atmosphere storage were investigated. The apples Aroma and Ingrid Marie were kept either in air or in controlled atmosphere (CA) storage. Some apples in both storage atmospheres were inoculated with Pezicula malicorticis, Penicillium expansum or Colletotrichum gloeosporioides, while others were not. Apples from each group were heat-treated at 40 degsC for 24, 48, 72 or 96 hours, while others were not.
In a separate test, groups were heat-treated as described earlier and then, after four months of storage, were dropped onto a wooden table to test for susceptibility to bruising. Fruits that were stored in air were least firm, but their firmness was improved by being pre-treated at 40 degsC for a minimum of 48 hours.
Extending the duration of heat treatment gave little additional benefit. It seems that an effective approach with CA storage would be to pre-treat apples at 40 degsC for 24 hours because this should reduce their susceptibility to bruising and fungal decay.
Improvement of Apple Quality and Storability by a Combination of Heat Treatment and Controlled Atmosphere Storage by Tahir, Johansson and Olsson (2009). HortScience 44 (6): 1648-1654. ISHS members can view HortScience from the website www.ishs.org.