In this edition: - The European Fruit Magazine

centration can be determined very rapidly (in real
time and online) and very accurately.
The method is based on measuring the fl uorescence
of the chlorophyll in the skin of the fruit by
using a FIRM TM Sensor (Fluorescence Interactive
Response Monitor) to monitor a sample of six
apples (Figure 1). If light of a certain wavelength
comes in contact with the chlorophyll of the apple,
the chlorophyll returns the light at a diff erent
wavelength (fl uorescence). Below a certain
oxygen level that is specifi c for the fruit, there is
a clear rise in the fl uorescence signal. Using this
information, it is possible to dynamically adjust
the atmosphere in the store to the ripeness, the
annual diff erences and the diff erences in origin of
the apples to be stored. The oxygen concentration
in the atmosphere is reduced to just above
the safe level.
DCA storage has been successfully introduced
in the North Italian fruit region of South Tyrol, by
Dr Angelo Zanella from the Laimburg research
station. After several years of scientifi c research,
followed by four years of large-scale practical
trials at several cooperatives, DCA storage was
used during the 2006/2007 storage season in a
total of 81 stores and during the 2007/2008 season
in 120 stores.
DCA storage has proved its value in South Tyrol, in
particular for varieties that are susceptible to scald
Figure 3: Due to its susceptibility to internal
browning, Braeburn is diffi cult to keep under ULO
conditions.
(including Granny Smith, Red Delicious, etc.).
The shelf life after DCA storage is also clearly better,
in particular with respect to the internal quality
(fi rmness and titratable acid) of the fruit and
fruit rot. DCA technology can be very interesting
for organic farmers for the storage of Topaz as it
off ers an alternative to the chemical post-harvest
treatment that they cannot use.
DCA storage trials for Braeburn
and Topaz in Austria
The positive experiences with DCA technology in
South Tyrol have resulted in many research stations
in Europe including the use of DCA technology in
CA 2
CA 1
DCA 2
DCA 1
kg/cm 2
6
12
6 6 24
0 10
10
9,5
9
8,5
8
7,5
7
6,5
6
9,0
DCA Storage trial Braeburn - Internal browning 2007/08
6 52
2 40
30
20 30 40 50 60 70 [%]
core browning cavities fl esh browning
Figure 4: The infl uence of various storage techniques and harvesting times on the occurrence
of internal browning in Braeburn
DCA Storagetrial Braeburn 2006/07 - fi rmness
their research programmes. Since 2006, the Haidegg
research station (Steiermark, Austria) has also
been working on DCA storage, and has purchased
six fl uorescence sensors for this purpose. In the
2006/2007 season, the research concentrated on
Braeburn, which, as is commonly known, is very
diffi cult to store in normal ULO stores due to its
susceptibility to internal browning (core and fl esh
browning, cavities) (Figure 3). In the 2007/2008
season, the apple variety Topaz and the pear variety
Uta, both grown by the organic sector, were
included in the research programme. In addition,
practical experience could be gained from a large
practical trial of DCA storage at a fruit trading
company.
In summary, the most important results of the
DCA Braeburn trials
• Reduction of core and fl esh browning by approximately
30 to 50%, depending on the moment
of harvesting (Figure 4)
• If the DCA conditions are incorrectly controlled
alcohol damage can occur
• SmartFresh exacerbates internal browning,
also in combination with DCA
8,7
8,6
8,4
8,9
8,6
7,8
8,9
8,3
8,2
15.02.2007 26.06.2007 06.07.2007
date of analysis
Figure 5: Graph showing the fi rmness of Braeburn apples kept diff erently during the
2006/2007 storage season
Info
DCA
DCA has the same objective
as DCS storage,
which is to keep the
oxygen level in the atmosphere
in the store
to just above the alcohol
formation level.
DCA uses a number of
sample apples and a
sensor to continually
monitor the chlorophyll
fl uorescence (see
text in article). Chlorophyll
fl uorescence is
related to the alcohol
content in the fruit.
7,3
31