2.4. Ripening treatments (Test 2)
Additional testing was performed in 2011 to more fully determine the impact on avocado quality of cold storage on partially-ripened fruit. Avocados were stored for 4 d at 5 °C in 90% RH followed by ripening at 20 °C and 95% RH in the presence of 50–60 μL L−1 ethylene until the fruit were 13.3–17.8 N (average 15.6 N) firmness as determined by an Imada penetrometer (Imada, Northbrook, IL, USA, 8 mm tip). This ripened fruit will be referred to as near ripe, the same designation as used in Test 1, although it should be recognized that the level of firmness was slightly softer than that used in the prior test. Fruit at this firmness would be desirable for retail or foodservice operations needing fruit nearing but not at the fully ripe stage where the fruit are at optimal eating firmness. The purpose of the initial 4 d at 5 °C was to help synchronize the ripening times of the fruit. Near ripe fruit were placed at 5 °C for either 7 d or 14 d at either 1 °C or 5 °C and then ripened to full ripeness at 20 °C and 95% RH in the presence of 50–60 μL L−1 ethylene. Comparison fruit were kept in continuous 5 °C storage after harvest until ripening, under the same conditions as the near ripe fruit, the initiation of ripening being timed so that the fruit would be ripe at the same time as the near ripe treatments and then act as controls to help discern the effect of cold storage of partially ripe fruit.