Postharvest treatments to reduce chilling injury symptoms in stored ...

ipen quickly once harvested. As with most fruits, it is possible to slowdown the ripening
process and extends the storage life by reducing the temperature of the fruits. However,
like many other tropical and subtropic al fruits, mangoes are prone to chilling injuries
when stored below critical minimum temperature (Chaplin et al., 1991; Lizada, 1991).
Recommended storage temperatures are generally within the range of 10 to 15 ºC
and lead to storage life after harvest of 2 to 3 weeks. Longer storage life could be
achieved if the resistance of mangoes to low temperature could be improved. This would
allow more fruits to be shipped to overseas’ markets.
3.2.1 Chilling injuries
Mangoes exposed to temperatures below the critical minimum temperature
develop severe physiological disorders referred to as chilling injury (CI) symptoms. The
primary cause of CI is to damage the cell membrane that initiates a cascade of secondary
reactions. CI is a time-temperature problem and some cultivars are more sensitive than
others (Mann and Singh, 1976; Farooqui et al., 1985; Fornaris-Rullan et al., 1989; and
Saucedo Veloz et al., 1977). CI symptoms include: grayish scald-like discoloration of the
skin, skin pitting, uneven ripening, reduction in the level of carotenoids, and poor aroma
and flavor (Abou-Aziz et al., 1976; Hatton et al., 1965; Thomas and Oke, 1983; Wardlaw
and Leonard, 1936).
3.2.2 Control of CI symptoms
Postharvest heat-treatments, plant growth regulators and antioxidants have been
successfully used to alleviate CI symptoms of tropical fruits. Moderate heat-treatments
reduce the incidence of CI symptoms in many tropical crops (Shellie and Mangan, 1994).
Heat-treatments induce heat shock protein (HSP), which protected products from both
heat injuries and CI. HSP also called stress proteins, and are a group of proteins that
present in all cells in all life forms. They are induced when a cell undergoes various types
of environmental stresses like heat, cold and oxygen deprivation (Woolf et al., 1995;
Klein and Lurie, 1991). The desired temperature and duration of the treatment is product-
dependent and its efficacy varies from product to product. The treatment is best applied
by immersion in a temperature controlled hot water (HW) bath. High temperatures affect
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