Chilling Injury

Chilling injury in banana fruit is caused by prolonged exposure to temperatures less than 13°C. This can occur during bunch development in the field or postharvest handling and storage. Mild symptoms of chilling injury are localised to peel tissue and reduce visual quality of fruit.

Symptoms include surface discoloration, dull or smokey color, subepidermal tissues reveal dark-brown streaks, failure to ripen, and, in severe cases, flesh browning. Chilling injury results from exposing bananas to temperatures below 13°C (56°F) for a few hours to a few days, depending on cultivar, maturity, and temperature. For example, moderate chilling injury will result from exposing mature-green bananas to one hour at 10°C (50°F), 5 hours at 11.7°C (53°F), 24 hours at 12.2°C (54°F), or 72 hours at 12.8°C (55°F). Chilled fruits are more sensitive to mechanical injury.

The main primary events in chilling injury are

low temperature-induce changes in the properties of cell membranes due to changes in the physical state of membrane lipids (membrane phase change)

production of reactive oxygen species (eg. hydrozen peroxide) that oxidize leading to altered enzymatic activities and structural proteins (e.g. tubulin) are disrupted.