Introduction and Overview - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 12

Biotechnology is a tool that can be utilized, in an interdis-
ciplinary approach, to address some of the concerns about
quality attributes and the biological causes of deterioration
of harvested produce (Kader, 2003; Pech et al., 2005). Three
approaches are being utilized to extend postharvest life
and maintain quality: selecting for slower ripening lines,
modification of ethylene responses, or reducing softening
rate. For example, papaya varieties having slow ripening
characteristics have been selected, delayed ripening by the
down-regulation of ethylene synthesis enzymes, ACC syn-
thase (ACS) and ACC oxidase (ACO), is being tested for
banana and papaya, and the modification of fruit soften-
ing related enzymes is being examined (Paull and Chen,
2004).
In some cases the goals may be contradictory, such as
lowering phenolic content and activities of phenylalanine
ammonialyase and /or polyphenoloxidase to reduce brown-
ing potential versus increasing polyphenols as antioxidants
with positive effects on human health. Another example
is reducing ethylene production versus increasing flavor
volatiles production in fruits. Overall, priority should be
given to attaining and maintaining good flavor and nutri-
tional quality to meet consumer demands. Extension of
postharvest life should be based on flavor and texture rather
than appearance only. Introducing resistance to physiolog-
ical disorders and/or decay-causing pathogens will reduce
the use of postharvest fungicides and other chemicals by
the produce industry. Changes in surface structure of some
commodities can help in reducing microbial contamination.
It is not likely that biotechnology-based changes in fresh
fruits will lessen the importance of careful and expedited
handling, proper temperature and RH maintenance, and ef-
fective sanitation procedures the throughout the postharvest
handling system.

POSTHARVEST LOSSES
Postharvest losses vary greatly among commodities and
production areas and seasons. In the United States, the
losses of fresh fruits and vegetables are estimated to range
from 2% to 23%, depending on the commodity, with an
overall average of about 12% losses between production
and consumption sites (Table 1.3). Estimates of postharvest
losses in developing countries are generally much higher
than those in the US and can be up to 50% in some fresh
fruits.
Kader (2005) estimated that worldwide, about one-third
of all fruits and vegetables produced are never consumed by
humans. The general difference between developed and de-
veloping countries is that more of the losses occur between
production and retail sites in developing than in developed
countries. It is not economical or practical to aim for 0%
losses, but an acceptable loss level for each commodity
production area and season combination can be identified
on the basis of cost-benefit analysis (return on investment
evaluations).
The basic requirements for maintaining quality and
safety of fruits between harvest and consumption sites
are the same in developing and developed countries. How-
ever, the extent of adoption of the specific harvesting and
postharvest handling technologies varies greatly among
countries and within each country, depending on scale of
operation, intended markets, and the return on investment
(cost/benefit ratio) of each technology (Kader, 2010). Al-
though labor costs are lower in developing countries, labor
training, productivity, and management are generally better
in developed countries. Availability and efficient use of the
cold chain is much more evident in developed countries
than in developing countries. Unreliability of the power
supply, lack of proper maintenance, and inefficiency of

Table 1.3. Estimated postharvest losses (%) of fresh produce in developed and developing countries.

Developed Countries Developing Countries

Location Range Mean Range Mean

From production to
retail site

2-23 12 5-50 22

At retail, food service,
and consumer sites

5-30 20 2-20 10

Cumulative total 7-53 32 7-70 32
Postharvest losses in selected countries: India (40 - 50%), Indonesia (20 - 50%), Iran (35 - 45%), Philippines (27 - 42%),
Sri Lanka (16 - 41%), Thailand (17 - 35%), and Vietnam (20 - 25%)

Source: Adapted from Kader (2005); Rolle (2006).