factors to consider when ripening avocadoucanr.edu/datastorefiles/234-2816.pdf · factors to...

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Factors to consider when ripening avocado

Factors to consider when ripening avocado

Mary Lu ArpaiaUniv. of CARiverside, CA

[email protected]

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’


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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


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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


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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


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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?


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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


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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)


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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


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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


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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 (%

)


0

5

10

15

20

25

20 25 30 35Body Rot (%

)


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


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Ripening Hass at different temperatures

65

67

69

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


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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


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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


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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.


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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 [email protected]

• UC Davis Postharvest Center websitehttp://postharvest.ucdavis.edu/

• California Avocado Commission websitehttp://www.californiaavocado.com/ripening-and-handling/

• General information on avocadoswww.avocadosource.com


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