Under-skin browning (USB) is a postharvest issue for 'Honey Gold' mangoes. Three sentences: The document summarizes research into reducing under-skin browning (USB), a postharvest issue for 'Honey Gold' mangoes, finding that slower cooling rates after harvest, reducing physical damage during harvest and transport through careful handling and soft liners, and increasing calcium nutrition through field treatments can help lower the incidence of USB. It acknowledges funding sources and collaborators on ongoing research to better understand and address USB.

1. Winning the battle against
under-skin browning
Peter Hofman, Gavin Scurr, Ted Winston, Daryl Joyce, Andrew Macnish,
PhD students

2. USB on ‘Honey Gold’

3. USB affected area
USB - under the microscope

4. KP
R2E2?
USB on other cultivars

5. Slower fruit cooling rates
Date
Mon 25 Tues 26 Wednes 27 Thurs 28
Temperature(
o
C)
10
15
20
25
30
Trt 1: tight stack
Trt 2: air stack
Trt 3: wrapped stack
10% affected
34% affected
52% affected

6. Physical injury during harvest and transport

7. Packaging/transport damage

8. Reducing transport damage - packaging
Treatment (packaging)
IncidenceoffruitwithUSB(%)
0
10
20
30
40
50 Liner (no transport)
Liner
Liner+wrap (fruit)
Liner + sock (fruit)
Wrap+pad (tray)
Fruit with any USB Fruit with USB > 3cm2
a
a
b
b
b
b
b
c
bc
c

9. USB test
The breakthrough
• Lightly abrade fruit
with sandpaper
• Hold at about 13°C
for at least 6 days
• Ripen

10. Long term focus
• How to produce a more robust fruit
• Harvesting
• Nutrition
• Irrigation
• Rootstocks
Under skin browning

11. Harvest time
2 am 6 am 10 am 2 pm 6 pm 10 pm
%offruitwithUSB>1cm2
10
20
30
40
50
60
70
80
average of no
and 1 day delay
Harvested every 4 hrs, cooled immediately or after 1 d
USB associated with abraded sites
Under skin browning – diurnal effects
Similar diurnal effects on USB not associated with abrasion

12. Field treatment
Control
P200 g /tree
P400 g /tree
Double bio gypsum
Percentage
0
10
20
30
40
50
60
% abrasion sites with USB
% of f riut with USB>1 cm
2
around abrasion sites
% of f ruit with USB>1 cm
2
not associated with abrasion
Ca reduced USB around abrasion sites and at other positions on the fruit
Under skin browning – Ca/P

13. Recommendations
• Reduce physical damage
– Harvest and pack carefully
– Use soft liners
– Reduce transport vibration/damage
• Delay cooling for at least one day
• Hold above 14-16ºC
Producing more robust fruit
• Harvest fruit at night
“Watch this space”
• Nutrition – calcium
• Irrigation
Under skin browning – so far

14. Acknowledgements and thanks
Funding
• Pinata Farms
• Horticulture Innovation Australia
• MG10009 and MG13016
• Dept Agriculture and Fisheries Qld
• University of Queensland