Agriculture Reference
In-Depth Information
but lower concentrations may be more effective. 1-MCP
and wax significantly delayed the ripening of 'Tower II'
avocado stored at 20°C (Jeong
et al
. 2003). Fruit treated
with both 1-MCP and wax had better retention of green
peel colour and fruit firmness, and delayed climacteric
ethylene evolution and respiration rates compared with
other treatments. Waxing alone reduced weight loss and
delayed softening, but did not delay climacteric ethylene
evolution and respiration rates. Whereas firmness of con-
trol fruit decreased from >100 to 20 N over a 7-day period
at 20 °C, fruit treated with both 1-MCP and wax required
more than 11 days at 20°C to soften to 20 N. The firmness
of waxed 'Booth 7' avocados declined from >170 to 15 N
during 19 days storage at 13°C whereas fruit treated with
both 1-MCP and wax required nearly 5 weeks to reach
firmness values of 25 N. 1-MCP works by attaching to a
site (receptor) in fruit tissues that normally binds to eth-
ylene, preventing ethylene binding, and therefore causing
the fruit to ripen and soften more slowly. 1-MCP was
sorbed faster and in greater amounts by 'Hass' avocado
fruit and avocado oil than by 'Cox' apple fruit and water,
respectively (Daunya
et al
. 2003), which may have an
influence on 1-MCP efficacy as a ripening inhibitor and
should be considered when prescribing commercial
1-MCP application strategies. At the time of writing
(2008) the application of 1-MCP is not commercially
used yet for avocado fruit.
of 'Fuerte' avocados by 4-5 days at 20°C, but fruit
irradiated at 50 Krad did not ripen, the tissue remained
hard and turned brown (Nogalingam 1993).
REFERENCES
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IRRADIATION
Extension of shelf life by gamma irradiation has been
successful for some fruits, but appears to hold little
prospect for avocado. Akamine and Goo (1971) found
avocado fruit to show surface and internal damage at 5
Krad. At this dosage and lower, the climacteric respiration
occurred earlier than that for controls, thus giving no
storage advantage. Smith and Jansen (1983) found 2.5
Krad to be the maximum safe dosage, but without signifi-
cant advantage. Young (1965) studied the effect of gamma
radiation on respiration, ethylene production and ripening
of 'Fuerte' avocados, and reported that irradiation in the
pre-climacteric phase at 5 and 10 krads caused an
immediate doubling of respiration and a small ethylene
production, 100 krads caused a doubling of respiration
and small ethylene production, but severe injury and fruit
did not ripen. Irradiation after the climacteric has been
initiated or in the post-climacteric phase had no effect on
ethylene production or respiration, nor was there any
effect on the appearance or quality of the fruit. Doses in
excess of 20 Krad seem to cause brown discoloration in
the mesocarp; 10 Krad resulted in extension of storage life
