Las bases para la maduracion de
paltas – factores a considerar
Mary Lu Arpaia
Univ. of CA
Riverside, CA
mlarpaia@ucanr.edu
Why Ripen Avocados?
Untreated, fruit
ripening may
range from a few
days to even
weeks within a
carton
Increase Uniformity
Decrease Checkerboarding
1
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
• A climacteric fruit showing an increase in
respiration and ethylene production during ripening
• Influenced by maturity, time after harvest,
temperature and atmosphere
150
Carbon Dioxide
400
Ethylene
ml CO 2/kg/hr
Adapted from
Eaks (1978) for ‘Hass’
300
200
50
ul C2H4/kg/hr
100
100
0
0
1
2
3
4
5
6
0
Days at 68F
2
Relationship between dry matter
(maturity) and final peel color
Final Peel Color = 3.06261- 0.00264DW
+0.0020DW 2
where DW = Dry weight
R2 = 0.621 ***
6.0
5.5
5.0
Peel Color
4.5
4.0
3.5
3.0
2.5
Actual Final Color
Predicted Final Color
2.0
1.5
1.0
10.0
22.8
Dry Matter (%)
Maturity and “days to ripe”
20
Days to Soft
1000 ppm propylene
no
yes
18
Average Days to Eating Ripeness <1.5
(
lbf) in response to 24
hour treatment of 40 ppm ethylene.
Days
16
15
14
Ethylene
NO
12
YES
RAIN
10
10
8
6
4
5
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17
Oil Content (%)
Eaks, 1980, JASHS (Harvest August - June)
0
1/25/00
3/7/00
4/18/00
6/1/00
7/11/00
8/22/00
Harvest Date
Ethylene hastens ripening regardless of stage of
maturity
3
Time 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
15
0 hr
24 hr
48 hr
Days to <1.5 lbf
10
5
Time after
harvest
decreases
the impact
of ethylene
0
0 days
7 days
14 days
Days at 5C
28 days
California ‘Hass’; average of 3 harvests; 3 grower lots per harvest, 2006
4
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)
California ‘Hass’
25
Days to Ripe
20
15
10
5
0
* g = ethylene
treatment
0 0g* 3 3g
0 0g 3 3g
Jan 27
Mar 7
0 0g 3 3g
Apr 18
0 0g 3 3g
0 0g 3 3g
Jun 1
Jul 11
0 0g 3 3g
Aug 24
Harvest Date/Storage/Ethylene
LH2000 - 25 fruit; San Diego fruit
Even within lots of fruit there is variability in ripening
– a way to control this is sorting by degree of
ripeness into different categories
25
20
15
10
5
0
0 0g 3 3g
0 0g 3 3g
0 0g 3 3g
0 0g 3 3g
0 0g 3 3g
0 0g 3 3g
5
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 Issues
Temperature
Ventilation/Air exchanges
Careful Monitoring
Prompt Movement of fruit
What is the proper stage of ripeness?
Where do you ripen the fruit?
6
Factors 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 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
7
Can I use a
banana ripening
room for avocado
ripening?
Some considerations
Peak Respiration
(mg/kg-hr)
Refrigeration Load
(BTU/T-day)
350
70000
300
60000
250
50000
200
40000
150
30000
100
20000
50
10000
0
0
Banana at 14C Banana at 18C Avocado at 20C
Banana at 14C Banana at 18C Avocado at 20C
8
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 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
9
How much to apply?
10, 100 ppm
1 ppm
0 ppm
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
Temperature 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
10
The impact of Temperature (24 or 48 hours) on ripening
performance of ‘Hass’ avocado
a
b
14
d
10
8
6
4
2
c
ab
30
25
bc
20
15
c
 High temperatures are5 DETRIMENTAL
0
25
30
35
 The outcome is delayed or20inhibited
Temperature (C) during 24 or 48 hr Holding
ripening and increased decay
25
 Keep temperatures below
21 C
a
10
20
0
20
25
30
35
Temperature (C) during 24 or 48 hr Holding
Body Rot (%)
Days to Ripe
12
Stem End Rot (%)
35
a
16
15
b
10
5
ab
b
0
20
25
30
35
Temperature (C) during 24 or 48 hr Holding
No significant difference due to duration
‘Hass’ Avocado
Ripening temperature influences final peel color
Cox et al, 2004, PH Biol. Tech.
11
Ripening Hass at different temperatures
9
8
7
6
5
4
3
2
1
0
Days to Ripe
Hue angle
15⁰C
18⁰C
20⁰C
23⁰C
Ripening Temperature
85
83
81
79
77
75
73
71
69
67
65
Hue Angle
Days to Ripe
Rate of ripening, final peel color, % body rots
25⁰C
Ripening Management
When 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 variable
The penetrometer is a tool to judge the relative
stage of ripeness
12
Ripening Management
What 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 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
13
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 retail
14
Example of an
overripe fruit
with stem end
rot, body rot
and internal
bruising
Example of fruit
shriveling
Example of a
stem end rot
A.
Example of
body rots
B.
A. Fruit with no bruising
under the peel.
B. Fruit which is very
overripe and is
exhibiting bruising
under the peel.
A.
B.
C.
A. Very ripe fruit
compressed by other
fruit on display.
B. Example of internal
bruising.
C. Very ripe fruit showing
severe internal
damage.
15
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
Checklist
Know the history of the fruit
Quality; don’t use stressed fruit
– More mature; less time
Standardize fruit size and
maturity
– After storage; less time
Uniform warming and cooling
• Time after Harvest
• Avoids delays in marketing
• Minimize fruit handling
Careful monitoring; don’t overripen
CONSUMER/MARKET Education
Additional information
• Contact me
mlarpaia@ucanr.edu
• UC Davis Postharvest Center website
http://postharvest.ucdavis.edu/
• California Avocado Commission website
http://www.californiaavocado.com/ripening-andhandling/
• General information on avocados
www.avocadosource.com
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