Avocado · Avocado Ripening Manual – 2 Purpose • To check that the product complies with the...
Transcript of Avocado · Avocado Ripening Manual – 2 Purpose • To check that the product complies with the...
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Avocado ripening manual
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AuthorsScott Ledger, Leigh Barker, Terry Campbell, Peter Hofman, Roberto Marques – Horticulture & Forestry Science, Agri-Science Queensland, Department of Employment, Economic Development and Innovation
AcknowledgmentsThis ripening manual was prepared for the project “Development of best practice guidelines for avocado ripening” (AV08018), which was funded by avocado grower levies and voluntary contributions which were matched by the Australian Government through HAL.
Appreciation is expressed to the following people for their contributions to preparing and testing the manual:•BenFranklin,BrettHeather,PhilipHall,DaleInd,MatthewOliver–CostaExchange•AndrewMead–SimpsonFarms•AntonyAllen,JoannaEmbryandJuliePetty–AvocadosAustralia
The International Avocado Quality Manual published by Plant & Food Research, New Zealand was used as a reference for descriptions and causes of common quality problems
Disclaimer© The State of Queensland, Department of Employment, Economic Development and Innovation and Avocados Australia Limited, 2011.The design, layout and Alvin Avocado are all trademarks of Avocados Australia Limited and may not be used without written permission of Avocados Australia Limited.Except as permitted by the Copyright Act 1968, no part of the work may in any form or by any electronic, mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be broadcast or transmitted without the prior written permission of the Department of Employment, Economic Development and Innovation and Avocados Australia Limited. The information contained herein is subject to change without notice. The copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information.
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Steps in ripening avocados ......................................................1
Receival assessment...................................................................2
Ripening conditions...................................................................3
What ripening conditions do I use? ......................................4
Time to reach required ripeness ...........................................5
How long can I store avocados before ripening? ..............6
Option1–14daysstoragepotential ....................................7
Option2–7daysstoragepotential ......................................8
Option3–3daysstoragepotential ......................................9
Option4–Ripenimmediately ............................................. 10
Storage after ripening ........................................................... 11
Ethylene injection .................................................................... 12
Venting rooms .......................................................................... 13
Monitoring fruit and handling conditions ...................... 14
Operatingaforced-airripeningsystem ........................... 15
Operatingastorageroom .................................................... 16
Common avocado quality problems ....................................17
Frequently asked questions ........................................ 25
Assessing fruit ripening ............................................ 27
Harvesting periods for Shepard and Hass .................. 28
Contacts and References ............................................. 29
Contents
1. Ripening
2. storage Before Ripening
3. storage After Ripening
4. Room operation
5. Problem solving
6. Appendices
Contents
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Avocado Ripening Manual – 11. Ripening
steps in ripening avocados
Check customer orders and space
availability
Check fruit ripeness and
prior handling practices
Store
Receival assessment
Plan ripening schedule
Ripen
Assemble order
Complete dispatch assessment
Dispatch to customer
Store
Ready for business
Sorting
Ready for use
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Avocado Ripening Manual – 2
Purpose• Tocheckthattheproductcomplieswiththespecificationandtoplantheripeningschedule.
sampling• Select3packagesoratleast50fruitfromacrossthesizerangeforeachgrowerandpackdate.
• Selectthepackagesfromdifferentpalletsandavoidthetop3layers.
• Recorddeliverydetailsonrecordform–brand,variety,deliverydate,typeandno.ofpackages.
• Recordlabeldetails–packer,grower,packdate,palletnumber,productID,count/fruitsize
Check prior handling practices• Checkpulptemperatureofafruitfromthemiddleofeachpackageandrecordthe
temperature.
• Calculatethenumberofdaysfrompackingtodelivery.
• Notethestage(early,midorlate)intheseasonforthevarietyanddistrict.
Check packing, fruit quality and ripeness• Weighthepackageandrecordthenetfruitweight.
• Observethepresentationandrecordifimprovementisneeded(egloosepack,mixedsizing,missingstickers).
• Photographthepackbeforeremovinganyfruitforassessment.
• Assesseachfruitforfirmnessandskincolour(Hass)andrecordifanyfruitaresofteningorcolouring.
• Assesseachfruitforexternalappearanceandrecordthenumberoffruitoutofgradeaccordingtodefecttype.
• Calculatethepercentageofout-of-gradefruitaccordingtomajorandminordefectsanddeterminewhethertheproduct
meetsspecification.
Provide feedback to grower/ packer• Sendelectroniccopyofreceivalassessmentrecordandphotographstogrower/packeraftercompletionofassessment.
• Requestextrainformationaboutpriorhandlingiffruitripeningisdetectedorifthereisuncertaintyaboutstoragepotential.
Plan ripening schedule• Checkcustomerorders,ripeningspaceavailableandstoragepotentialusingthedecisiontreeonpage6.
Receival assessment
Inspection
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Avocado Ripening Manual – 3
Ripen mature fruit• Fruitmustbematuretoripenproperly-minimumof23%drymatter(Hass)and21%(Shepard)
• Themorematurethefruit,thequickertheripeningtimeandthedarkertheskincolourofripeHass
Room temperature – 16 to 20°C• Useaforced-airsystemtoprecoolorwarmfruitandmaintainpulptemperaturesduringripening
• Ripenat18-20°cforlessmaturefruit(lessthan26%drymatter)
• Ripenat16-18°cformorematurefruit(26%andhigherdrymatter)
• Holdfruitattherequiredtemperatureuntilitreachesaripenesslevelreadyfordispatch
• Hightemperaturesincreasetheriskofrotsandfruitmayripentooquickly
• LowtemperatureswillreduceskincolourdevelopmentinHass
• Fruitpulptemperaturesaretypically1-2°caboveroomtemperature
ethylene duration and concentration• Precoolorwarmfruittoripeningtemperaturebeforeinjectingethylene
• Duration: first2-3daysforlessmature,earlyseasonfruit
first1-2daysformoremature,midtolateseasonfruit
• Concentration: tricklesystem:10ppmcontinuousethylene
Shot system: 100ppm ethylene every 6 to 8 hours
Maintain room humidity• Maintainatleast85%relativehumidity
Room venting• Ventroomstomaintaincarbondioxidelevelbelow1%
• Tricklesystem:ventroomscontinuouslytoallowatleastoneroomvolumechangeeveryhour
• Shotsystem:ventroomsbyopeningdoorsforatleast10-15minutesevery6-8hours
Ripening conditions
Packed with frie
nds
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Avocado Ripening Manual – 4
What ripening conditions do I use?
Check grower/packer details• Variety• Stageinseason/fruitmaturity• Riskoffruitrots
What is the risk of fruit rots?
Late season: morethan26%
dry matter
What is the risk of fruit rots?
Early to mid-season: 26%orless dry matter
HIgH
LoW
HIgH
LoW
• TheskinofearlyseasonHass(drymatterlessthan26%)maynotbefullydarkwhenripe.
• TheskinofHasswilldarkenmorewhenripenedat18-20°Cthanat16-17°C
• Thehighertheripeningtemperature,thefasterthegrowthofrots.
• Theriskofrotsdevelopmentdependsonvariety,growingconditions,orchardmanagementand postharvest fungicide treatment. Wet weather favours infection in the orchard.
Ripenat16-18°Cwithethyleneforfirst2-3days
and hold at temperature until ready for dispatch
Ripenat18-20°Cwithethyleneforfirst2-3days
and hold at temperature until ready for dispatch
Ripenat16-18°Cwithethyleneforfirst1-2days
and hold at temperature until ready for dispatch
Ripenat16-20°Cwithethyleneforfirst1-2days
and hold at temperature until ready for dispatch
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Avocado Ripening Manual – 5
time to reach required ripeness stage
VARIETYRipening
temperature
Ripening time (days from start of ethylene treatment)
Hard to rubberyRubbery to softening
softening to firm ripe
Hass16°C 6-7 3-4 2-3
18°C 4-5 2-3 1-2
20°C 3-4 2-3 1
Shepard16°C 5-6 2-3 2
18°C 3-4 1-2 1
20°C 2-3 1 1
Assumption: Ripening time assumes fruit were harvested mid season and have been exposed to ethylene
Ripeness stage DescriptionHard No give with strong thumb pressureRubbery Slight give with strong thumb pressureSoftening Fruit deforms 2-3mm with moderate thumb pressureFirm ripe Fruit deforms 2-3mm with slight thumb pressure
Factors affecting the time to ripen: • Fruitmaturity• Temperaturemanagementandfruitage• Ripeningtemperature• Exposuretimetoethylene• Farmlocation• Blocklocationonfarm• Productionpractices
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Avocado Ripening Manual – 62. storage before ripening
How long can I store avocados before ripening?
Check ripeness on arrival at ripening
facility
Fruit sorted for ripeness
Some fruit softening
8-12°Cpulp temp
5-7°Cpulp temp
Higher than 12°Cpulptemp
No sorting for ripeness
All fruitHard
Less than 5 days from packing
5 or more days from packing
Less than 5 days from packing
1-2 days from packing
5 or more days from packing
3-4 days from packing
Hard fruit
5+ days from packing
softening/colouring fruit
OPTION1:14 days storage potential
OPTION2:7 days storage potential
OPTION3:3 days storage potential
OPTION4:Ripen immediately
Storage potential before ripening depends on ripeness, the pulp temperature on arrival at ripening facility and fruit age.
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Avocado Ripening Manual – 7
5-7°Cpulptemp
Less than 5 daysfrom packing
14 days storage potential
All fruit hard
• Fleshgreying/browningcanoccuriffruitstartstoripenduringstorage.
• Fruitmustbeprecooledeffectivelyto5-7°Cwithin36hoursofharvestandtransportedat5-7°C.
• Ifthefruitageismorethan5daysfrompacking,reducethestorageperiodbefore ripening.
• Placethefruitintothestorageroomwithin4hoursofreceivalattheripening facility.
• Checkfruitconditionandlengthoftimeinstorageeveryday.Removefruitif there is a risk of fruit starting to ripen.
• Donotstorelateseasonfruitformorethan5days.
option 1 storage before ripening – 14 days storage potential Check fruit condition and age on arrival at warehouse
CautIon
Variety Storage temperature
Hass 5°C
Shepard 7°C
Othergreenskins 7°C
RipeningStageOne:Hard
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Avocado Ripening Manual – 8
5-7°Cpulptemperature
8-12°Cpulptemperature
Higherthan12°Cpulp temperature
5 or more daysfrom packing
Less than 5 daysfrom packing
1-2 daysfrom packing
7 days storage potential
All fruit hard
• Fleshgreying/browningcanoccuriffruitstartstoripenduringstorage.
• Hightemperaturesonarrivalincreasetheriskoffruitstartingtoripeninstorage.Precoolwarmfruit(higherthan12°C)to5°Cwithin12hoursofarrival.
• Placecoldfruit(lessthan12°C)intothestorageroomwithin4hoursofreceival at the ripening facility.
• Checkfruitconditionandlengthoftimeinstorageeveryday.Removefruitif there is a risk of fruit starting to ripen.
option 2 storage before ripening – 7 days storage potential Check fruit condition and age on arrival at warehouse
CautIon
Variety Storage temperature
Hass 5°C
Shepard 7°C
Othergreenskins 7°C
RipeningStageOne:Hard
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Avocado Ripening Manual – 9
8-12°Cpulptemperature
Higherthan12°Cpulp temperature
5 or more days from packing
3-4 days from packing
3 days storage potential
All fruit hard
• Fleshgreying/browningcanoccuriffruitstartstoripenduringstorage.
• Hightemperaturesonarrivalincreasetheriskoffruitstartingtoripeninstorage.Precoolwarmfruit(higherthan12°C)to5°Cwithin12hoursofarrival.
• Placecoldfruit(lessthan12°C)intothestorageroomwithin4hoursofreceival at the ripening facility.
• Checkfruitconditionandlengthoftimeinstorageeveryday.Removefruitif there is a risk of fruit starting to ripen.
option 3 storage before ripening – 3 days storage potential Check fruit condition and age on arrival at warehouse
CautIon
Variety Storage temperature
Hass 5°C
Shepard 7°C
Othergreenskins 7°C
RipeningStageOne:Hard
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Avocado Ripening Manual – 10
Higherthan12°Cpulp temperature
Any pulp temperature
5 or more days from packing
Any days from packing
Ripen immediately
All fruit hard
some fruit softening/ colouring
• Fleshgreying/browningmayoccurifripeningfruitisplacedintostorage.
• Loadsthatarrivewithmixedripenesscanbesortedbypackdatesandripeness.
• Selecttheoldestpackdatesandripeningfruitimmediately.Storehardgreen fruit for a maximum of 3 days.
option 4 Ripen immediately – do not store before ripening Check fruit condition and age on arrival at warehouse
CautIon
Variety Storage temperature
Hass 5°C
Shepard 7°C
Othergreenskins 7°C
RipeningStageOne:Hard
Ripening Stage Three:Softening
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Avocado Ripening Manual – 113. storage after ripening
storage after ripening
VarietyStorage
temperature
Storage time (days)
Rubbery softening Firm ripe
Hass 5-7°C 7 day max 5 day max 3 day max
Shepard 6-8°C 5 day max 3 day max 3 day max
Othergreenskins 6-8°C 5 day max 3 day max 3 day max
The risk of grey/ brown flesh or vascular browning occurring increases with storage time after ripening and as storage temperature decreases
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Avocado Ripening Manual – 124. Room operation
systems
• shot injection – one volume of ethylene injected every 6-8 hours to achieve 100ppm in ripening room
• trickle injection – continuous measured flow of ethylene to achieve 10ppm in ripening room
• Catalytic generation – one volume of gas generated every 6-8 hours to achieve 100ppm in ripening room
• Controlled monitoring – ethylene level in ripening room is monitored and ethylene is injected when concentration drops below set point of 10ppm – carbon dioxide level is also monitored and vents are opened when concentration reaches setpointof1%
ethylene injection
EthyleneisavailableincylindersaspureethyleneorRipegas™,whichcontains4-5%byweightofethyleneand7%byvolume. If pure ethylene is used, special safety precautions are required to prevent explosions.
Inatypicalshotsystem,therequiredvolumeofgasisfirstflushedintoasecondarycylinderbeforeinjectingthisvolumeinto the room.
With catalytic generators, ethanol is poured into the generator and catalysed into ethylene. The amount of ethanol required is calculated to match the room volume.
Shot system
Catalytic generation
trickle system
Controlled monitoring
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Avocado Ripening Manual – 13
A system for positively venting the ripening room is requiredtoremovecarbondioxide(CO
2). Carbon dioxide is
produced by the ripening fruit and will build up if the room isnotregularlyflushed.Carbondioxidelevelsabove1%inhibitfruitripeningandareahealthhazardtooperators.Concentrationsof3-5%causeincreasedrespirationandheadachesand8-15%causeheadache,nauseaandvomitingand may lead to unconsciousness. Concentrations as high as 12%havebeenmeasuredinfruitripeningrooms.
Venting systems
• Shotsystemsandcatalyticgenerators – room is manually vented by opening the doors for 10-15 minutes every 6-8 hours. Run the room fans to flush the room.
• Tricklesystem – room is continuously vented with inlet and outlet vents. The inlet vent is typically behind the cooling coils to suck in fresh air. Carbon dioxide is heavier than air so the outlet vent is best placed on a wall near the floor. The vents need to be large enough to allow at least one room volume change every hour.
• Controlledmonitoring – A sensor is placed inside the room and monitors the level of carbon dioxide. Inlet and outlet vents are placed in the same positions as for the tricklesystem.Whenthecarbondioxidelevelreaches1%,the outlet vent is opened, a fan is started and the room is flushed.Oncetheroomisflushedtheoutletventisclosed.
Venting rooms
a fan connected to the outletvent helps to flush the room
outlet vent is placed near the
floor and can be closed when n
ot
flushing the room
For the controlled monitoring system
,
a carbon dioxide sensor opens
the
vent when the level reaches 1%
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Avocado Ripening Manual – 14
temperature• Checksettemperaturesdaily
for ripening and storage rooms. Calibrate the room temperature gauges with a temperature logger at least monthly to ensure the gauges are accurate.
• Spotcheckpulptemperaturesatleast monthly to ensure that fruit temperatures are uniform within pallets and between pallets. Probe fruit through the stem end and check packages in different layers and on opposite sides of the pallet. Do not check fruit in the top three layers as the temperature may not be representative of other fruit in the pallet.
ethylene• Ethyleneismonitoredusingagas
aspirating pump (eg Kitagawa) and detector tubes.
• Spotcheckripeningroomsweeklyto ensure correct concentration is being injected during ripening.
• Spotcheckstorageroomsweeklytoensure that ethylene is not present in room.
Carbon dioxide
• Carbondioxideismonitoredusingagas aspirating pump (eg Kitagawa) and detector tubes.
• Spotcheckripeningroomsweeklytoensurethatlevelsdon’texceed1%.
Ripeness
• Checkfruitdailyinripeningroomsto monitor the ripening rate.
• Checkfruitdailyinstorageroomsandremoveatfirstsignofripening.
• Checkpackagesindifferentlayersand on opposite sides of the pallet.
• Donotcheckfruitinthetopthreelayers as ripeness may not be representative of other fruit.
shelf life (library samples)
• Samplefruitatdispatchandholdinanairconditionedroom(20-23°C)toassess shelf life.
• Selectfruitweeklyforeachvarietyfrom each grower/ packer to monitor for seasonal effects.
• Assessthefruitwhenripeforskincolour (Hass), external appearance and flesh quality.
Monitoring records
• Monitoringrecordshelptoidentifyproblems and areas for improvement and provide feedback to growers/ packers.
• Ahandlinglogrecordsroomconditions (temperature, ethylene, carbon dioxide) and tracks fruit movement from receival to dispatch.
• Ashelflifeassessmentrecordtogether with photographs provides feedback to grower/ packers on fruit quality.
Monitoring fruit and handling conditions
Gas pump and detector tube
temperature data logger
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Avocado Ripening Manual – 15
Forced-air coolers enable effective control of fruit temperature during ripening, provided the containers are suitable and the pallets and room are stacked to optimise air movement across the fruit. If uneven amounts of air flow through different layers or pallets, ripening will be uneven within and between pallets. Air will always take the path of least resistance and flow through gaps around containers and pallets rather than through the containers.
operating a forced-air ripening system
Checklist for forced-air ripening systems:• Arethecontainersstackedsothatthesidewiththemost
ventilation area is aligned to allow maximum air flow through the pallet?
• Arethecontainersstackedincolumnstoensureevenairflow through all layers on the pallet?
• Arethepalletsplacedtightlyagainsttheplenumandalongtherowtominimizegapsbetweenthepallets?
• Arelargegapsbetweenpalletscoveredtopreventairbypassing through the containers on the pallets?
• Whenripeningpalletswithdifferenttypesofcontainers,are the pallets with containers having the least amount of ventilation placed at the front of each row (near the plenum) and pallets with containers having the most ventilation placed at the back of the row?
• Aretheheightsofthepalletstacksevenbetweenthetworowssothatthetarpfitstightlywithoutanygapsunderneath?
• Foropentopcontainers,doesthetarpcoverthefullwidthof the 2 rows of pallets or the tops of pallets are covered to prevent air leaking under the tarp?
Place pallets with least ventilation at front of row near fan
Stack pallets to same height
along the 2 rows to ensure tarpfitstightly
without gaps underneath
Cover the top row of open
top trays.
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Avocado Ripening Manual – 16
Ensure a space of at least 10cm is left around all sides of pallets during storage to allow effective air circulation to maintain fruit temperatures.
operating a storage room
Allow a space of at least 10cm around pallets to ensure effective air movement
Pulptemperaturevariationbetweenlayersonthepalletduetoinsufficientaircirculationduringstorageat5°C.Fruitonoppositesidesofpalletinthe4thlayerwere3°Chigherthanfruitinthetoplayer.
Time (hours)
Tem
pera
ture
(°C
)4
8
12top layer - fruitlayer 4 - fruitlayer 4 - fruittop layer - air
warehousereceival
storage room (5°C)
12 24 36 48
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Avocado Ripening Manual – 175. Problem solver
• Checkfruitmaturity–drymattershouldbeabove23%(Hass)and21%(Shepard).
• Checktheroomtemperaturesetting and calibrate the room temperature gauge to ensure it is accurate.
• Checkcarbondioxidelevelsandventing.
• Shotsystem–Manualflushingofroom may not be frequent enough. Openthedoorstoventtheroomevery 6-8 hours.
• Tricklesystem–Thesizeofinletand outlet vents may not be large enough or the length of the outlet pipe may be too long or the outlet vent may not be located correctly (near floor). At least one room air change per hour is required.
• Checkethylenelevelandtreatmentduration. Inject ethylene into ripeningroomforfirst2-3daysforearlyseasonfruitandforfirst1-2days for mid-late season fruit.
Fruit ripens too slowly
Carbondioxidelevelinshotripeningroomroseto2.5%in 18 hours until door was opened to vent room
slow ripening More than 6 days from start of the
ethylene treatment
What is it?• Fruittakesmorethan7daysto
reach softening stage.
What causes it?• Immaturefruitripenslowlyeven
if ethylene is used.
• Lowfruittemperature–thelowerthe temperature, the slower the ripening.
• Highcarbondioxide–levelsabove1%caninhibitripening.
• Faultyethyleneinjection–emptygas bottle or leakage/ blockage in injection system.
How can it be minimised or prevented?
RipeningStageOne:Hard
Ripening Stage Three:Softening
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Avocado Ripening Manual – 18
• Checkethylenelevelandtreatmentduration.
• Checkthegrower/packerdetailsandpackdates.Ifthepalletsarestackedwithdifferentgrowers/packersordifferentpack dates, ripening rate is likely to vary. Restack pallets with the same grower or similar pack dates.
• Checkthepackagedesign.Istheventilationsuitabletoallowenoughairtoflowacrossthepallet?Atleast4%ofthesideof the package must be vented.
• Checkthestackingofpallets.Stackpalletswithpackagesthathavesimilarventilationareaonallsidesorcolumnstackthe packages.
• Checkpalletandtarpplacement.Lookforgapsbetweenthepalletsandunderthetarp.Airwillalwaystakethepathofleast resistance.
• Ifthereisamixtureofpalletsontheforcedaircooler,placepalletshavingtheleastamountofventilationatthefrontnear the fan. For example, stack pallets with cartons at the front and pallets with plastic returnable crates at the back.
Uneven ripening
What is it?• Fruitripeningisunevenwithintrays,betweentraysinpallets
or between trays on different pallets in the ripening room.
What causes it?• Variablefruitmaturity.Fruitmaturityvarieswithintraysand
ripening rate will vary if fruit are ripened without ethylene.
• Variablefruitage.Ifthepalletsarestackedwithpackagesfrom different growers/ packers or different pack dates, ripening rate is likely to vary.
• Variablefruittemperature.Thehigherthetemperature,the faster the ripening rate. Avocados generate heat during ripening and if not removed, temperature will rise and fruit will ripen quicker. This can occur if package ventilation is insufficientorifpalletsarecrossstackedorifpalletswithdifferent packages are placed in the ripening room.
How can it be minimised or prevented?
Tem
per
atu
re (
°C)
4
8
12
16
20
24
28
layer 4 - outsidelayer 4 - inside
Tue Wed Thu Fri
Inside (green) of the pallet rose 6°Chigherthanoutside (red) due toinsufficientairflow through the pallet. Cooling after ripening was also slower. Inside fruit were one ripeness stage ahead of outside fruit.
If ethylene level or
duration is insufficient,
ripening rate will vary
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Avocado Ripening Manual – 19
Poor skin colour of Hass
What is it?• Thefruitsoftensbuttheskin
fails to darken evenly as the fruit ripens.
• Skinappearsmottledwithareasof brown, purple and green.
What causes it?• Fruitmaturity–earlyseasonfruit
with low dry matter content do not colour well.
• Lowripeningtemperature–thelower the ripening temperature, the less the fruit colours.
How can it be minimised or prevented?• Selectripeningtemperaturebased
on maturity/ season.
• Ripenearlyseasonfruitat 18-20°C.
• Lateseasonfruitcanberipenedat16-18°Ctoproduceacceptableskincolour.
Ripen early season fruit at18-20°Cforgoodcolour development
Temperature too low (less than 18ºC) for early season fruit
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Avocado Ripening Manual – 20
Dark patches on skin
What is it?• Irregularblackorbrownpatchesontheskin.Thedarkpatchesvaryinsizefromsmallpatchesto large solid areas.
• Symptomsonlyoccurontheskinanddonotpenetrate into the flesh, which distinguishes the injury from fruit rots.
• BecomeslessobviousinHassastheskincolours.
What causes it?• Chillinginjuryduringstorageandtransportcan
cause irregular dark patches on the skin (usually more than 3 mm diameter).
• Injurymayoccurifunripefruitisstoredortransportedbelow5°Cformorethan 7 days.
• Growingregionmayinfluencethetemperaturethreshold for damage.
• Symptomsincreaseafterthefruitisremovedfrom storage or transport.
How can it be minimised or prevented?• Donotstoreortransportunripefruitbelow5°C
for longer than 7 days.
• Calibratetheroomtemperaturegaugeswithatemperature logger at least monthly to ensure the gauges are accurate.
Irregular dark patches on the skin caused by storing unripefruitbelow5°Cfor
longer than 7 days
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Avocado Ripening Manual – 21
Flesh bruising
Susceptibility to bruising increases as fruit ripens and with drop height
Flesh bruising appears as dark areas with relatively distinct margins and often with cracking or air cavities
Firm ripe (stage 4) Softening (stage 3)
100mmdrop
250mmdrop
What is it?• Darkareasinthefleshusuallybrownorbrown/
black in colour and with relatively distinct margins.
• Crackingandaircavitiescanbeassociatedwiththis discolouration.
What causes it?• Impactdamagefromdroppingofpackages,
bumps to pallets during fork lift operation, and knocks/ shocks during transport (road, air, sea).
• Severityincreaseswithfruitripenessandimpactlevel (eg drop height).
How can it be minimised or prevented?• Checkworkersforroughhandlingoffruit,
packages, and pallets, particularly after fruit has been ripened.
• Re-trainworkersifroughhandlingisdetected.
• Usesuitablevehiclesfortransportingripenedavocados (eg correct suspension).
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Avocado Ripening Manual – 22
grey/ brown flesh
What is it?• Darkareasinthefleshusuallygreytogrey/brownincolourandwithpoorlydefinedmargins.
• Usuallystartsatthebottomandneartheseedandspreadsupwards and outwards.
• Vascularbrowningmaybeassociatedwithgrey/brownflesh.
What causes it?• Storingortransportingfruitfortoolongpriortoripeningor
at too low a temperature after ripening.
How can it be minimised or prevented?Before ripening
• Donotstoreearly-midseasonfruitbeforeripeningforlongerthan 14 days and late season fruit for longer than 5 days.
• Poortemperaturemanagementfollowingpackingandduring transport will shorten storage time prior to ripening.
• Ethylenepresentduringstoragemaytriggerripeningandcause early onset of symptoms.
• Checkfruitconditionandlengthoftimeinstorageeveryday.Remove fruit if there is a risk of fruit starting to ripen.
After ripening
• Afterripening,donotstoreHassforlongerthan7daysorShepard for longer than 5 days. See Section 3 - for further information.
• Checkinternalqualityofripenedfruitheldinstorageeverydayandremoveatfirstsignoffleshdiscolouration.
Flesh discolouration usually starts at the bottom and
near the seed and spreads upwards and
outwards.
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Avocado Ripening Manual – 23
Vascular browning
What is it?• Browningofthevascularbundles(strands)whichrun
longitudinally through the flesh and carry fluids from the stem to the base of the fruit.
What causes it?• Storageoffruitfortoolongbeforeripening.
• Maybeassociatedwithstemendrot.
How can it be minimised or prevented?• Donotstoreearly-midseasonfruitbeforeripeningforlonger
than 14 days and late season fruit for longer than 5 days.
• Poortemperaturemanagementfollowingpackingandduring transport will shorten storage time prior to ripening.
• Highethylenelevelsduringstorageortransportmaytriggerripening and cause early onset of symptoms.
• Checkfruitconditionandlengthoftimeinstorageeveryday.Remove fruit if there is a risk of fruit starting to ripen.
Browning of the vascular bundles may be caused by
stem end rot or storage of fruit before ripening for too long.
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Avocado Ripening Manual – 24
Fruit rots
What is it?Body rot
• Discretebrownorblackdiscolouredareasontheskin–mayalsoshow light brown/ pink spores in severe cases. Infection may not be obvious on the skin of coloured, ripe Hass.
• Spreadsfromtheskinintothefleshandappearsasbrownsemi-circular areas. Brown patches under the skin can indicate the presence of rots.
Stem end rot
• Discolouredareaontheskinandintheflesh,spreadingfromthestem end and often associated with vascular browning. Infection may not be obvious on the skin of coloured, ripe Hass.
• Thediscolouredareaisusuallysofterthanthesurroundingflesh.
What causes it?• Poorfieldhygiene.Infectionoffruitoccursonthetreeandthe
organisms remain dormant until the fruit starts to ripen.
• Incorrectorpoorapplicationoffungicidetreatmentsinthe pack shed.
• Fruitripeningathightemperaturesabove22°C.
• Fruitoverripe–holdingripenedfruitfortoolong.
How can it be minimised or prevented?• Checkthegrower/packerdetails.Infectionlevelsvarybetween
growers and the effectiveness of the postharvest fungicide.
• Checktheripeningroomtemperature.
• Ripenfruit,suspectedtobeinfectedwithbodyorstemrots,at 16-18°C.
• Donotholdfirmripefruitatroomtemperatureforlongerthan 3 days.
external body rot
Body rot in flesh stem end rot
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Avocado Ripening Manual – 25
What do I do if the fruit arrives hot?• Checkthefruithistory–stageofseasonandpackdates.SeeSection2.Storagebeforeripening–formoreinformation.
• Ripenfruitimmediatelyifthetemperatureisabove12°Candfruitageis5ormoredaysfrompackingorifthefruitislateseason.
• Ifthefruitareearly-midseason,thetemperatureisabove12°Candthetimefrompackingislessthan5days,thefruitmaybestoredbeforeripeningforupto3days.Precoolfruitto5°Cwithin4hoursofarrival.Checkfruitconditionandlengthof time in storage every day. Remove fruit if there is a risk of fruit starting to ripen. High temperatures on arrival increase the risk of flesh discolouration developing during storage.
What do I do if fruit arrives already softening or colouring?• Ripenthefruitimmediately.Donotstorethefruitatlowtemperatureastheriskoffleshdiscolourationoccurringishigh.
What temperature do I use for ripening avocados?• Ripenearlyseasonfruitat18-20°Candmid-lateseasonfruitbetween16-20°Cdependingonhowquicklyyouneedtoripen
the fruit. The higher the ripening temperature, the better the skin colouring of Hass, but the risk of fruit rots increases. See Section 1. Ripening – for more information.
How much ethylene do I add to the ripening room and for how long?• Thereare4methodsforinjectingethyleneintotheripeningroom–shot,catalyticgenerator,trickle,andcontrolledmonitoring.Use100ppmethylenefortheshotandcatalyticgeneratormethodsand10ppmforthetrickleandcontrolledmonitoring methods. The duration of the ethylene treatment is 2-3 days for early season fruit and 1-2 days for mid-late season fruit. Spot check ripening rooms weekly to ensure correct concentration is being injected during ripening. Refer to Section 3. Room operation – for more information.
What temperature and for how long can I store avocados before and after ripening?• StoreHassat5°Candothergreenskinvarietiesat7°C,beforeandafterripening
• Beforeripening,fruitmaybestoredforupto14daysdependingonthearrivaltemperature,andthefruitmaturityandage. See Section 3. Storage before ripening – for more information.
• Afterripening,Hasscanbestoredforupto7daysandShepardfor5days.RefertoSection4.Storageafterripening–formore information.
Frequently asked questions
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Avocado Ripening Manual – 26
What causes uneven ripening of avocados within and between pallets?• Unevenripeningmaybecausedbyripeningmultiplegrowersorpackdatesinthesameroom,insufficientethylene
concentration or duration, or uneven fruit temperatures.
• Ifthereisfruitfromdifferentgrowers/packersordifferentpackdatesintheroom,theripeningrateislikelytovary.Check the package labels at receival for details of the grower and packer and the pack dates, and segregate batches that may ripen differently.
• Theripeningrateoffruitwithinpackagesvariesduetomaturitydifferences.Gassingavocadoswithethyleneincreasestheuniformity of ripening. Check the ethylene level and treatment duration. Gas early season fruit for 2-3 days and mid-late season fruit for 1-2 days.
• Fruittemperaturevariationswithinripeningroomsmaybecausedbyplacingdifferentpackagesintheroom,variablestacking of the pallets and the location of the pallets. In a forced-air system, air will always take the path of least resistance. If the container ventilation space is too small or there are gaps between pallets or under the tarp, there may not be enough air flowing through the pallets. The temperature on the inside of the pallet will be higher and the fruit will be riper than the outside of the pallet.
• Ideallyitisbesttohavethesamepackageonallpalletsintheripeningroom.Wherethisisnotpossible,positionthepallets so that the less ventilated packages are placed at the front nearest to the forced-air fan and the packages with the most ventilation placed further away. Air flow should be as even as possible across all pallets.
• Refertothedescriptionof“Unevenripening”onpage18formoreinformation.
Why do I lose my breath when I walk into a ripening room?• Thisisasureindicationthatthelevelofcarbondioxidehasreachedahighconcentration(3-5%)andisaffectingyourbreathing.Aswellasbeingahealthhazard,carbondioxidelevelsabove1%willinhibitripening.Avocadosgeneratecarbondioxide during ripening and the level will build up if the room is not vented effectively.
• Venttheroomimmediatelybyopeningthedoor(s)for10-15minutes.Refertosection4.Roomoperationforinstructionsonventing for the various types of ripening systems.
What temperature do I use if I only have one room available for storing Hass and shepard?• DuringtheShepardseason,setthetemperatureofthestorageroomat7°C.Hasscanbestoredatthistemperaturebut
reduce the storage period to 10 days maximum. Check fruit condition and length of time in storage every day. Remove fruit if there is a risk of fruit starting to ripen.
• OncetheShepardseasoniscomplete,setthetemperatureofthestorageroomat5°C.
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Avocado Ripening Manual – 276. Assessing Fruit Ripeness
Firmness measurement
Firmness Hand feel Instron Newtons 10mm tip, 2mm skin
Densimeter Firmometer 200g weight
Penetrometer 11mm tip, no skin
1. Hard No give with strong thumb pressure >25 N 92-96 <10 >5 kgf force
2. RubberySlight give with strong thumb pressure
20-25 N 90-91 10-20 5-10 kgf force
3. SofteningDeforms 2-3mm with moderate thumb pressure
10-20 N 86-89 20-60 2-5 kgf force
4. Firm ripeDeforms 2-3mm with slight thumb pressure
5-10 N 74-85 60-80 1-2 kgf force
5. Medium-soft ripe Deforms with moderate hand pressure <5 N 65-73 >80 <1 kgf force
Assessing fruit ripeness
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Avocado Ripening Manual – 28
gRoWIng AReAs JAn FeB MAR APR MAy JUn JUL AUg seP oCt noV DeC
Atherton Tablelands
Bundaberg – Childers
Sunshine Coast
Tamborine – Blackall Ranges
Lockyer Valley
Toowoomba
Northern NSW
Central NSW
Tristate
Perth
South West WA
shepard Hass
Harvesting periods for shepard and Hass Avocados
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Avocado Ripening Manual – 29
ethylene gas
• BOC(pureEthylene,Ripegas™(www.boc.com.au)
• AirLiquide(pureethylene)(www.airliquide.com.au)
Catalytic ethylene generators
• QASupplies(www.qasupplies.com)
temperature/ humidity monitoring equipment
• OneTemp(dataloggers)(www.onetemp.com.au)
• HastingsDataLoggers(www.hdl.com.au)
• ECEFast(dataloggers,meters)(www.ecefast.com.au)
• RSAustralia(thermometers)(www.australia-rs-online.com)
gas monitoring equipment (ethylene, carbon dioxide)
• EEMuir(Kitagawagasaspirationpump)(www.eem.com.au)
• Air-MetScientific(detectortubes/pump)(www.airmet.com.au)
• Vaisala(carbondioxidedatalogger)(www.vaisala.com)
Controlled monitoring equipment
• ControlledRipeningSystemsAustralia(GTAutomaticFruitRipener)(www.crsa.net.au)
technical advice
• AgrilinkManual
• DEEDIwebsite(www.dpi.qld.gov.au)
• AvocadosAustraliawebsite(www.avocado.org.au/industry)
Contacts
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Avocado Ripening Manual – 30
• TheInternationalAvocadoQualityManual,Plant&FoodResearch, New Zealand (www.plantandfood.com)
• AvocadoMaturityTestingGuide
• Avocadohandlingposters
o Avocado colour and ripeness chart
o Avocado handling – packhouse
o Avocado handling – wholesale
o Avocado handling – retail
• Avocadohandlingguides
o Avocado ripening guide
o Avocado handling training guide
o Defect guide
o Harvesting season calendar
o Australian growing areas
• Avocadotrainingmodules
o Physiology of avocados
o Avocado quality loss
o Managing avocado ripening and storage
o Handling avocados in export destinations
• Avocadohazardanalysis
References
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this material has been produced using avocado grower levies and Voluntary Contributions which have been matched by the Australian government through HAL.
© 2011 Copyright Avocados Australia
facebook.com/AustralianAvocados
www.avocado.org.au/industry