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Factors to consider when ripening avocado
Factors to consider when ripening avocado
Mary Lu ArpaiaUniv. of CARiverside, CA
mlarpaia@ucanr.edu
Why Ripen Avocados?Why Ripen Avocados?
Increase UniformityDecrease Checkerboarding
Untreated, fruit ripening may range from a few days to even weeks within a carton
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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History of commercial ripening
• J. Biale first described avocado ripening process (1941)
• I. Eaks outlined proper ripening protocols (1966)
• Lee and Coggins outline feasibility of commercial ripening and enhanced purchasing (1982)
• Henry Avocado and V. Tokar begin first large scale CA avocado ripening program (1983)
• US consumption climbs from < 1.0 lb/person (1980) to 4.5 lb/person (2011)
What we know about the avocado and why it responds to ethylene
What we know about the avocado and why it responds to ethylene
• A climacteric fruit showing an increase in respiration and ethylene production during ripening
• Influenced by maturity, time after harvest, temperature and atmosphere
0 1 2 3 4 5 6
Days at 68F
0
50
100
150
0
100
200
300
400Carbon DioxideEthylene
ml C
O2/
kg/h
r
ul C2 H
4 /kg/hr
Adapted fromEaks (1978) for ‘Hass’
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Relationship between dry matter (maturity) and final peel color
Final Peel Color = 3.06261- 0.00264DW+0.0020DW2
where DW = Dry weightR2 = 0.621 ***
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
10.0 22.8
Pee
l Co
lor
Dry Matter (%)
Actual Final Color
Predicted Final Color
Maturity and “days to ripe”Maturity and “days to ripe”
Eaks, 1980, JASHS (Harvest August - June)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Oil Content (%)
4
6
8
10
12
14
16
18
20Days to Soft
1000 ppm propyleneno yes
Ethylene hastens ripening regardless of stage of maturity
Average Days to Eating Ripeness (<1.5 lbf) in response to 24 hour treatment of 40 ppm ethylene.
1/25/00 3/7/00 4/18/00 6/1/00 7/11/00 8/22/00
Harvest Date
0
5
10
15
Days
Ethylene
NO YESRAIN
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Time after harvestTime after harvest
• Ethylene has maximum benefit within 1-2 weeks of harvest
• Imported fruit if conventional shipment will need less time (24 hours or less)
• Imported fruit if CA shipped or 1-MCP treated may need longer treatment times
Time after harvest
California ‘Hass’; average of 3 harvests; 3 grower lots per harvest, 2006
0
5
10
15
0 days 7 days 14 days 28 days
Day
s to
<1.
5 lb
f
Days at 5C
0 hr
24 hr
48 hr
Time after harvest decreases the impact of ethylene
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Harvest Date/Storage/Ethylene
Jan 27 Mar 7 Apr 18 Jun 1 Jul 11 Aug 24
LH2000 - 25 fruit; San Diego fruit
Note the affect of maturity, storage (3 wks @ 5C) and ethylene (50ppm) on the amount of days to ripe to <1.5 lbf at 20C as well as the
variability of the data (checkerboarding)
0 0g 3 3g 0 0g 3 3g 0 0g 3 3g 0 0g 3 3g 0 0g 3 3g 0 0g 3 3g0
5
10
15
20
25
* g = ethylene treatment
*
Day
s to
Rip
eCalifornia ‘Hass’
Even within lots of fruit there is variability in ripening – a way to control this is sorting by degree of ripeness into different categories
0 0g 3 3g
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Suggested treatment times for California ‘Hass’ avocados
Suggested treatment times for California ‘Hass’ avocados
• Early season fruit (November –February) 36 – 72 hours
• Mid-season fruit (March – June) 24 – 36 hours
• Late season fruit (July – October) 8 - 24 hours +/- ethylene
Management IssuesManagement Issues
TemperatureVentilation/Air exchanges
Careful MonitoringPrompt Movement of fruit What is the proper stage of ripeness?Where do you ripen the fruit?
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Factors under your controlFactors under your control
Educate yourself about the potential differences between varying sources of fruit – there are differences
• Pre-ripening inspection• Ripening management• Postripening management
Ripening ManagementRipening Management
• Uniform heating and cooling is ABSOLUTELY ESSENTIAL• Refrigeration needs to control the heat (6000 BTU per
pallet)• Forced air ripening is critical (1000 cfm/pallet) • Venting (preferably flow through, keep CO2 below 1%)• Source of Ethylene – as low as possible; physiologically you
only need ~10 ppm but practically use 100ppm• Fruit needs to be easily accessible in ripening room for
monitoring; especially if fruit is of varying arrival condition or multiple lots of fruit
• Keep good records
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Can I use a banana ripening
room for avocado ripening?
Some considerations
0
50
100
150
200
250
300
350
Banana at 14C Banana at 18C Avocado at 20C0
10000
20000
30000
40000
50000
60000
70000
Banana at 14C Banana at 18C Avocado at 20C
Peak Respiration (mg/kg-hr)
Refrigeration Load(BTU/T-day)
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Can I use a banana room….. With some practical modifications
Refrigeration during ripening and cooling of fruit likely to be insufficient in a banana room
– Hot spots within pallet
– Uneven ripening
Do not to overload the room
Ethylene dose considerationsEthylene dose considerations
• Ethylene concentration– >20 ppm; no more than 100 ppm
• Fruit Maturity– Less mature; longer treatment
• Time after Harvest– With increasing time after harvest;
shorter durations needed
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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How much to apply?How much to apply?
Short exposures to ethylene can trigger ripening; threshold is believed to be around 10 ppm
Commercial application of 20 -100 ppm is recommended
Source: I. L. Eaks, UC, Riverside
10, 100 ppm
1 ppm
0 ppm
Temperature ManagementTemperature Management
• Avocados have a VERY high rate of respiration during ripening = HEAT
• Efficient warming/cooling of fruit essential
• Airflow essential to maintain proper pulp temperature (20C)
Impact of high temperatures– Delayed/uneven ripening– Increased decay
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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The impact of Temperature (24 or 48 hours) on ripening performance of ‘Hass’ avocado
0
2
4
6
8
10
12
14
16
20 25 30 35
Days to Ripe
Temperature (C) during 24 or 48 hr Holding
0
5
10
15
20
25
30
35
20 25 30 35
Stem End Rot (%
)
Temperature (C) during 24 or 48 hr Holding
0
5
10
15
20
25
20 25 30 35Body Rot (%
)
Temperature (C) during 24 or 48 hr Holding
dc
ba
c
bc
aba
b
bab
a
High temperatures are DETRIMENTAL The outcome is delayed or inhibited
ripening and increased decay Keep temperatures below 21 C
No significant difference due to duration
Ripening temperature influences final peel colorCox et al, 2004, PH Biol. Tech.
‘Hass’ Avocado
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Ripening Hass at different temperatures
65
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71
73
75
77
79
81
83
85
0
1
2
3
4
5
6
7
8
9
15⁰C 18⁰C 20⁰C 23⁰C 25⁰C
Hue Angle
Days to Ripe
Ripening Temperature
Days to Ripe
Hue angle
Ripening ManagementWhen do you turn off the gas?
Ripening ManagementWhen do you turn off the gas?
• You don’t need the gas until ripe; a short duration treatment will “trigger” ripening
• Fruit may soften but may not color – maturity and other factors involved
• The best way to gauge the rate of softening is with a penetrometer…not your fingertips or buttons “popping”
• Fruit maturity is an important variableThe penetrometer is a tool to judge the relative
stage of ripeness
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Ripening ManagementWhat should you do with ripe fruit?
Ripening ManagementWhat should you do with ripe fruit?
• Cool immediately; ideally within ripening room• How long can you hold the fruit? Depends on
the stage of ripeness• Ripe fruit (<2 lbf) can be held at lower
temperature generally than unripe/partially ripe fruit; minimize peel damage
• Fruit will continue to soften in storage but has minimal impact on fruit flavor
• Risk of decay increases with longer holding periods
Managing Ripe FruitManaging Ripe Fruit• Decay increases with increasing ripeness;
accelerates in “overripe” fruit• Don’t hold fruit for long periods of time that are
partially ripe – increased chilling injury• Bruising increases with advancing ripeness –
Protect fruit• Peel color at “slicing” or “guacamole” ripe does
not necessarily mean the fruit needs to be completely black!
These are issues wherever fruit are ripened
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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The outcome of “ripe” fruit
Ripe fruit at retail level has greatly increased consumption,
HOWEVER…..
• Greater challenge in temperature management
• Fruit sensitivity to damage greatly enhanced
Problems at retailProblems at retail
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Example of fruit shriveling
Example of an overripe fruit with stem end rot, body rot and internal bruising
Example of a stem end rot
Example of body rots
A.
A. Fruit with no bruising under the peel.
B. Fruit which is very overripe and is exhibiting bruising under the peel.
A. Very ripe fruit compressed by other fruit on display.
B. Example of internal bruising.
C. Very ripe fruit showing severe internal damage.
B.A.
C.
B.
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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Considerations for successful avocado ripening
Considerations for successful avocado ripening
• Temperature management is CRITICAL– Too high; ripening
inhibited and increased decay
– Too low; ripening is slowed and lose benefit
• Fruit Maturity– More mature; less time
• Time after Harvest– After storage; less time
• Avoids delays in marketing• Minimize fruit handling
Checklist
Know the history of the fruit
Quality; don’t use stressed fruit
Standardize fruit size and maturity
Uniform warming and cooling
Careful monitoring; don’t overripen
CONSUMER/MARKET Education
Additional informationAdditional information
• Contact memlarpaia@ucanr.edu
• UC Davis Postharvest Center websitehttp://postharvest.ucdavis.edu/
• California Avocado Commission websitehttp://www.californiaavocado.com/ripening-and-handling/
• General information on avocadoswww.avocadosource.com
Arpaia, Mary Lu "Ripening Avocados" (c) 2015 Postharvest Technology Center, UC Davis
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