In this edition: - The European Fruit Magazine

30
Info
Dr. Gottfried Lafer
gottfried.lafer@stmk.gv.at
Practical experience with
new storage technologies in Austria –
Dynamic CA (DCA) storage and SmartFresh TM
DCA or DCS
Dynamic Controlled
Atmosphere (DCA)
and Dynamic Control
System (DCS) are both
systems that reduce
the oxygen content in
the store atmosphere
to just above the level
at which alcohol is
formed. When DCS
technology is used,
during the fi rst weeks
of being stored various
apple samples are
checked for the fi rst
signs of alcohol formation.
If this is not
found, the oxygen in
the air in the store can
be carefully lowered.
When signs of alcohol
are found, the oxygen
level is raised, to eventually
reach a stable
level, just above the alcohol
formation level.
Following the introduction of Controlled Atmosphere
(CA) storage in the nineteen fi fties, the introduction
of DCA storage and the acceptance of
1-methylcyclopropene (1-MCP) represented a new
giant step in the storage of fruit. By dynamically
adapting the storage conditions to the physiological
status and the activities of the apples, a further
improvement in fruit quality can be achieved without
supplementary post-harvest treatments.
The active ingredient 1-MCP (registered under the
trade name ´SmartFresh´) eff ectively prevents the
formation of ethylene, which in turn delays the
ripening and aging of the fruit.
The use of SmartFresh is extremely interesting in
particular due to the improvement in internal fruit
quality after storage (shelf life) and in the prevention
of physiological storage problems.
What is DCA storage?
When Dynamic Controlled Atmosphere (DCA)
storage is used, the oxygen level in the cold store
is lowered in steps down to near the lowest level
tolerated by the fruit, the so-called anaerobic compensation
point. During storage, the atmosphere
is continually adjusted to the physiological condi-
Figure 1: When DCA is used, the fl uorescence of the
chlorophyll in the skin of the fruit is measured by a
FIRM TM Sensor that monitors a sample of six apples.
(Photos: Gottfried Lafer)
tion of the fruit. This critical oxygen level is not a
fi xed value, but varies, dependent on variety, ripeness
and length of time the fruit has been stored,
from between 0.3 and 0.6% O 2 . By measuring the
Chlorophyll fl uorescence, this critical oxygen con-
Figure 2: Graph showing the fl uorescence signal during the entire storage period (end of October 2007 to mid
March 2008)