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.1.
Chilling injury of lemons, grapefruit and oranges
-
stability and effects of waxes under protocol regimes
- effect of pre-cooling temperatures on fruit.
- increasing the cold sterilization temperature to decrease
fruit damage (market access).
- increasing resistance of fruit to chilling injury.
- testing alternatives to cold sterilization.
Chilling
injury is especially relevant to South Africa, as fruit is
shipped at -0.5 Celsius for insect sterilization purposes.
To commercially cool a batch of fruit to that temperature,
some of the fruit is cooled to - 1.5 degrees Celsius. Three
types of damage can be identified, i.e., pitting, sunken areas
on fruit and glassy looking fruit that appears as though it
has been frozen. The systems we have developed ensure that
we successfully export commercial fruit to markets that require
a cold sterilization procedure. However, in some situations
we still experience losses due to Chilling Injury and research
is under way to address this. The effect of pre- and post-harvest
factors on the occurrence of chilling injury and post-harvest
pitting are being investigated, as is the use of gamma irradiation
as an alternative to cold sterilization.
2. Rind breakdown in Clementines, Minneolas and midseason
and Valencia oranges
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Identifying causes of Rind Breakdown including pre-harvest
factors such as climatic conditions and cultural practices
and post-harvest temperature and atmosphere management as
well as packhouse treatments.
-
Post-harvest treatments to increase resistance to breakdown
Rind
Breakdown is a rind pitting problem that has been responsible
for considerable losses in the markets. It is primarily influenced
by macro climatic conditions, but a number of secondary "triggers"
are known, e.g., fruit borne inside the tree are more susceptible
and rind carotenoid pigments play a role in susceptibility
when combined with certain post-harvest conditions.
3.
Peteca spot on lemons
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Factors that cause Peteca spot
- Treatments to induce resistance to development of peteca
spot.
This
is probably another form of rind breakdown, and similar approaches
to the work on rind breakdown are being taken.
4.
Creasing
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A study of the physiological causes of creasing and new methods
of prediction and prevention
Creasing
is a serious rind disorder in many parts of the world. Present
control measures have undesirable side effects and hence work
to clarify the physiological basis of the disorder so as to
develop appropriate control measures.
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