Dynamic controlled atmosphere (DCA) storage uses varying oxygen levels optimized for avocados to extend storage life while maintaining quality. DCA monitoring detects fruit stress to determine safe oxygen levels. Testing on New Zealand 'Hass' avocados showed DCA prolonged storage life, shortened ripening time, and reduced rot compared to air or static controlled atmosphere storage. DCA could enable New Zealand avocado exporters to supply more distant markets by maintaining quality over longer transport and storage periods.

1. The New Zealand Institute for Plant & Food Research Limited
Dynamic CA storage of avocados
Technology for managing exports?
Jem Burdon

2. Presentation overview
• Why dynamic CA (DCA) storage?
• What is DCA and how is it operated?
• How does New Zealand ‘Hass’ respond to DCA?
• DCA as a technology for managing exports?
The New Zealand Institute for Plant & Food Research Limited

3. Why dynamic CA storage?
• Export based industry
• Storage life to reach markets
• Quality after prolonged storage
The New Zealand Institute for Plant & Food Research Limited

4. Why dynamic CA storage?
Alternative technologies:
• Refrigeration, Air
Insufficient storage life
High rot incidence
• CA with low O2 and high CO2
• SmartFresh(SM)
Both: Increased storage life
Prolonged ripening period
High rot incidence
The New Zealand Institute for Plant & Food Research Limited

5. Effect of SmartFresh on ripe fruit quality
Air SmartFresh
Days to ripen 4.1d 10.5d
Stem End Rot 29% 74%
Body Rot 38% 78%
External Rot 5% 52%
Diffuse Flesh Discoloration 14% 1%
The New Zealand Institute for Plant & Food Research Limited

6. What is dynamic CA?
Static CA (SCA)
a pre-determined O2 level is maintained
Dynamic CA (DCA)
O2 level is set dependent on the fruit response to low O2
Allows greater optimisation and matching of storage
conditions to the fruit tolerance to low O2
Improved CA effect at low CO2 level
The New Zealand Institute for Plant & Food Research Limited

7. Dynamic CA: Monitoring the fruit
The New Zealand Institute for Plant & Food Research Limited

8. Monitoring fruit stress under low oxygen
Stress monitored as skin fluorescence by HarvestWatch™
5 3500
3000
4
Fluoroscence (FIRM )
TM
2500
Oxygen (%)
3
2000
2
1500
1
1000
0 500
0 12 24 36 48 60 72 84 96
Time (hours)
The New Zealand Institute for Plant & Food Research Limited

9. Oxygen levels in SCA and DCA
20
18
Low O2 stress point
16 Back-off
14 Lowest safe O2 level
Frequency
Oxygen (%)
12
Spike
10
8
6
Static
4
2 Dynamic
0
c c c c c c
3 De 7 De De De De De
11 15 19 23
The New Zealand Institute for Plant & Food Research Limited

10. How does NZ ‘Hass’ respond to DCA ?
Comparison of fruit stored in air, SCA and DCA
Key aspects
• fruit condition at the end of storage
• time to ripen
• disorders when ripe
The New Zealand Institute for Plant & Food Research Limited

11. At the end of storage
Skin Colour Fuzzy Patch
50 50
40 40
Colour (0-100%)
Incidence (%)
30 30
20 20
10 10
0 0
Air SCA DCA Air SCA DCA
The New Zealand Institute for Plant & Food Research Limited

12. Time to ripen
Time to ripen
8
Days to ripen 6
4
2
0
Air SCA DCA
The New Zealand Institute for Plant & Food Research Limited

13. When ripe
Stem End Rot Body Rot External Rot
100 100 100
80 80 80
Incidence (%)
60 60 60
40 40 40
20 20 20
0 0 0
Air SCA DCA Air SCA DCA Air SCA DCA
The New Zealand Institute for Plant & Food Research Limited

14. When ripe
Diffuse flesh discoloration
100
80
Incidence (%)
60
40
20
0 0
0
Air SCA DCA
The New Zealand Institute for Plant & Food Research Limited

15. How does NZ ‘Hass’ respond to DCA ?
DCA is suitable for NZ ‘Hass’
• prolonged storage life
• short ripening time
• reduced rots
The New Zealand Institute for Plant & Food Research Limited

16. DCA as a technology for managing exports?
Onshore
Harvest better fruit / when favourable weather and store
Supply out of inventory
Dependent on suitable facilities
Export
More distant markets
Improved quality
Dependent on capability of shipping containers
The New Zealand Institute for Plant & Food Research Limited

17. Acknowledgements
Work funded by:
Foundation for Research Science and Technology
Avocado Industry Council
We are grateful to all those growers and sheds who have
assisted us conducting this research over recent years
Team: P&FR: Jem Burdon, Nagin Lallu, Glen Haynes,
Matt Punter, Paul Pidakala, David Billing
AIC: Henry Pak, Jonathan Dixon
The New Zealand Institute for Plant & Food Research Limited

18. The New Zealand Institute for Plant & Food Research Limited
www.plantandfood.com
JBurdon@hortresearch.co.nz
The New Zealand Institute for Plant & Food Research Limited