Agriculture Reference
In-Depth Information
right environmental conditions exist (Snowdon, 1990). Some infections, such
as anthracnose, are called latent infections, as the initial infection occurs with
little pathogen growth while the fruit is green and only becomes visible as the
fruit ripens and the fruit's natural resistance mechanisms are breaking down.
The major factors that determine whether a pathogen attack will be successful
in germinating and colonizing the fruit are the cuticle, which acts as a
morphological barrier, the presence of stomata and lenticels as a pathway for
entry, and the broken peduncle. Other factors postharvest are the physiological
state of the fruit such as having been subject to chilling temperatures, the
presence of inhibitors that frequently decline during ripening and the storage
temperature. As with respiration, lower temperature reduces pathogen growth
and limits disease development.
Control methods include preharvest and postharvest disease control using
fungicides. The loss of postharvest fungicides has led to renewed interest and
the use of alternative methods to control disease postharvest. The approaches
have included heat treatments such as the 49°C for 20 min hot water dip
for papaya and the use of natural biostatic compounds and chemicals such
as sodium bicarbonate. These approaches are often not as ef ective as some
fungicides and need to be used in a systems approach that includes more
ef ective sanitation.
FOOD SAFETY
Since fresh fruits and vegetables are raw agricultural products grown in fi elds,
they can be expected to be in contact with a wide range of microorganisms
(Brackett, 1999; Zagory, 1999). Many are plant pathogens and other
microorganisms, but human pathogens at low levels can also be expected.
Recent food safety outbreaks have raised concerns about human pathogen
survival and proliferation on fresh produce. The increase in outbreaks could
refl ect better reporting, more complex handling systems, multiple sources,
greater opportunities for contamination and wide distribution of potentially
contaminated products. The US Centers for Disease Control reported that,
from 1983 to 1992, only 3% of traceable outbreaks of food-borne diseases
were associated with source and supply. Most were associated with postharvest
handling (77%) and the home (20%). These incidents occurred primarily
during the warmer summer months. Poor sanitation and improper hygiene
were the major source.
The management of temperature and relative humidity (RH) used during
shipping and storage is a critical component in maintaining a safe food supply.
Temperature and relative humidity are two major criteria used to defi ne
critical limits in monitoring programmes associated with the hazard analysis
and critical control point (HACCP) system. HACCP is a preventive quality-
assurance system and is required so that safety programmes can be properly
 
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