(2) Discoloration. The discoloration may occur externally as in beans, or
internally, as in eggplant. The spots or areas may be tan, brown, or black. They may
become evident while the product is at low temperature or show primarily after transfer
of the item to a nonchilling temperature. Internal discoloration may be noticeable
immediately upon cutting the vegetable or only after the injured tissue has been
exposed to air.
(3) Pitting. Pitting of the surface is an early symptom of chill injury. Under
relatively dry conditions, the injured cells apparently lose moisture more rapidly than it
can be transported to them. Desiccation then results in the collapse of the cells and the
formation of pits.
(4) Abnormal ripening. The prevention of normal ripening caused by chill
injury is seen in mature-green tomatoes and honeydew melons. In tomatoes, coloration
is uneven. Desirable softening is delayed in both, and severe chilling may prevent the
fruit from ever reaching an edible stage even if decay is absent. However, sensitivity to
chilling decreases progressively in some fruits as they ripen, so that ripe tomatoes can
tolerate low temperature more readily than pink fruits. In turn, the pinks can tolerate low
temperatures better than mature-green fruits.
(5) Texture changes. The development of hard core in sweet potatoes is a
texture change due to chill injury. This defect is characterized by the development of a
mass of tissue that does not soften even upon cooking.
d. Level of Resistance to Chill Injury. Figure 5-4 lists the susceptibility of
various vegetables and melons to chill injury.
Moderate to low
Moderate to low
Figure 5-4. Susceptibility of vegetables and melons to chill injury.