Temperature Effects on Produce Degradation 621
For each chilling-sensitive crop species, there is a unique temperature at or below
which chilling injury will occur. This threshold or lowest safe temperature is the
basis for the widely circulated “recommended” or “optimum” storage and handling
temperatures for various chilling-sensitive crops. The lower the temperature below
the threshold temperature and the longer the exposure, the worse the chilling injury
will be. The critical threshold temperature below which injury develops ranges from
less than 5°C for apples and oranges to 10 to13°C for mangoes and 12 to 13°C for
bananas.^30 Cucumbers, eggplants, papayas, and peaches are injured below about
7°C. The critical temperatures and symptoms of chilling injury for a variety of fruit
and vegetables are provided in Table 20.5.
FIGURE 20.9Chilling injury of two cultivars of sweet potatoes. Roots on left, stored 6
months at 10°C (50°F), show injury symptoms such as shriveling, surface pitting, and fungal
decay not seen in roots on right stored for the same period at 15°C (59°F). (Photo courtesy
of A.A. Kader, University of California, Davis.)
FIGURE 20.10Browning under the skin, observed as brown or black streaks in a longitudinal
cut, is a dependable indication of chilling injury of bananas. (Photo courtesy of A.A. Kader,
University of California, Davis.)