Agriculture Reference
In-Depth Information
GENERAL CHARACTERISTICS OF TROPICAL FRUIT
Like all fresh fruit and vegetables, tropical fruits have four general
characteristics that need to be understood and considered during postharvest
handling. These characteristics are the reason why postharvest technology is
needed. The characteristics are:
1.
All fresh fruits after harvest are still living and respiring.
2.
All fresh fruits have a high water content (~90%), and after harvest it is no
longer being replaced from the plant yet they continue to lose water.
3.
All fresh fruits are subject to pathogen attack before and after harvest.
4.
All fresh fruits are made up of diverse morphological structures, with the
edible tissues varying between dif erent fruits, and hence they have dif erent
composition and physiology.
The edible fruit tissues in tropical fruits are derived from many tissues, such as
the fl oral receptacle in strawberry and cashew, the fused clustered fl owers in
pineapple, the entire pericarp in tomato, the exocarp and mesocarp in apple
and peach, the mesocarp only in papaya, the endocarp in citrus, the aril tissue
arising from the funicle in litchi and durian, and the seed coat in rambutan
(Fig. 1.1). This diversity needs to be understood as it infl uences how a fruit will
respond to postharvest handling treatments.
The objective of postharvest handling is to minimize adverse changes in
these characteristics, especially respiration, dehydration and pathogen attack.
Losses postharvest are tied directly to these adverse changes, often associated
with poor storage environment and mechanical injury. Mechanical injury,
besides causing unsightly scarring, also increases water loss and susceptibility
to pathogens. The component of the storage environment over which we have
the greatest control postharvest is temperature. Proper storage temperature
and avoiding mechanical injury are the two most important variables in
postharvest handling.
POSTHARVEST PHYSIOLOGY
Tropical fruit physiology does not dif er from the basic knowledge gained from
studies of temperate and subtropical fruits. Dif erences occur between fruits in
the major substrates involved in ripening, the rate of ripening and senescence,
and in some cases variation in the order in which various components of
ripening occur. The aspects of tropical fruit physiology that make these fruits
unique are:
• their chilling sensitivity;
• the generally more rapid ripening of climacteric tropical fruits when
compared to temperate fruits; and
