mitcham-modified controlled atmospheres short course...

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Modified and Controlled Atmospheres during Transit and Storage

Modified and Controlled Modified and Controlled Atmospheres during Atmospheres during Transit and StorageTransit and Storage

Beth MitchamDepartment of Plant Sciences

Postharvest Technology CenterUC Davis

Beth MitchamBeth MitchamDepartment of Plant SciencesDepartment of Plant Sciences

Postharvest Technology CenterPostharvest Technology CenterUC DavisUC Davis

Modified or ControlledAtmospheres InvolvesModified or ControlledModified or ControlledAtmospheres InvolvesAtmospheres Involves

• Reduced oxygen

• Increased carbon dioxide

• Removing carbon dioxide

• Removing ethylene and other volatiles

• Degree of precision differentiates MA and CA

•• Reduced oxygenReduced oxygen

•• Increased carbon dioxideIncreased carbon dioxide

•• Removing carbon dioxideRemoving carbon dioxide

•• Removing ethylene and other volatilesRemoving ethylene and other volatiles

•• Degree of precision differentiates MA Degree of precision differentiates MA and CAand CA

Nitrogen 78%

Oxygen 21%

CarbonDioxide .03%

Nitrogen 94%

CarbonDioxide 4%

Oxygen 2%

Normal Atmosphere Typical Desired Atmosphere

Gas CompositionGas Composition

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How have you used or benefited from the use of CA/MA

in your position?

How have you used or benefited from the use of CA/MA

in your position?

A. Within packaging

B. During shipment

C. Storage of product

D. Have not used

A.A. Within packagingWithin packaging

B.B. During shipmentDuring shipment

C.C. Storage of productStorage of product

D.D. Have not usedHave not used

Modified AtmospheresPotential Benefits

Modified AtmospheresModified AtmospheresPotential BenefitsPotential Benefits

• Retards senescence or ripening– Reduces respiration rate– Reduces ethylene production

• Reduces ethylene sensitivity• Alleviates certain physiological

disorders• May reduce decay either indirectly or

directly• Insect control

•• Retards senescence or ripeningRetards senescence or ripening–– Reduces respiration rateReduces respiration rate–– Reduces ethylene productionReduces ethylene production

•• Reduces ethylene sensitivityReduces ethylene sensitivity•• Alleviates certain physiological Alleviates certain physiological

disordersdisorders•• May reduce decay either indirectly or May reduce decay either indirectly or

directlydirectly•• Insect controlInsect control

AIRAIRAIR 1% O2 + 5% CO21% O1% O22 + 5% CO+ 5% CO22

5 weeks at 10ºC5 weeks at 105 weeks at 10ººCC

Low O2 Delays Ripening of ‘Santa Rosa’ Plums

3

-1ºC (30ºF) in Air-1ºC (30ºF) in 2% O2

Six Months Storage of Bartlett Pears

Low O2 Retards Ripening of Partially Ripe Tomato Fruit

Low Low OO22

Delayed Ripening of Chili Peppers

4

CA Reduces Chilling Injury and Resulting Decay

Air Control <0.01ppm Ethylene + 0.1ppm Ethylene

+ 1ppm Ethylene + 10ppm Ethylene

‘Hass’ Avocado9 weeks 5ºC (41ºF)

5 days at 20ºC (68ºF

2% O2 + 2.5% CO2

Reducing Chilling Injury of Avocado with CA

CA Treatments for Decay ControlCA Treatments for Decay ControlCA Treatments for Decay Control

• Oxygen concentrations < 1%

• Carbon dioxide concentrations >10%

•• Oxygen concentrations < 1%Oxygen concentrations < 1%

•• Carbon dioxide concentrations >10%Carbon dioxide concentrations >10%

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AIR

20% CO2

0°C (32°F) 2.2°C (36°F) 5°C (41°F)

4 Weeks Storage

AIR 5% O2 + 15% CO2

3½ Months Storage

What condition can result from CA/MA?

What condition can result from CA/MA?

A. Brown spotting

B. Internal browning

C. Failure to ripen

D. Sprouting

E. All of the above

A. Brown spotting

B. Internal browning

C. Failure to ripen

D. Sprouting

E. All of the above

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Modified AtmospheresPotential Hazards

Modified AtmospheresModified AtmospheresPotential HazardsPotential Hazards

• Causes or aggravates physiological disorders in product

• Causes irregular ripening

• Induces off-flavors/odors

• Increases decay susceptibility

•• Causes or aggravates physiological Causes or aggravates physiological disorders in productdisorders in product

•• Causes irregular ripeningCauses irregular ripening

•• Induces offInduces off--flavors/odorsflavors/odors

•• Increases decay susceptibilityIncreases decay susceptibility

2% O2 0.2% O2Air 25ºC

Low OLow O22 Stimulates Sprouting and Increases DecayStimulates Sprouting and Increases Decay

Low O2 Injury in Apples

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2% O2 + 5% CO2 at 0ºC for 1 week or longer

Brown Stain

COCO22 Injury to Apple FruitInjury to Apple Fruit

20% CO20% CO2 2

1% O2 + 5% CO1% O2 + 5% CO2 2

4 wks at 04 wks at 0°°C (32C (32°°F)F)2d 202d 20°°C (68C (68°°F) AirF) Air

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Modified AtmospheresPotential for Benefit or Hazard

Depends Upon:

Modified AtmospheresModified AtmospheresPotential for Benefit or Hazard Potential for Benefit or Hazard

Depends Upon:Depends Upon:

• Commodity

• Cultivar

• Physiological age

• Atmospheric composition

• Temperature

• Duration

•• CommodityCommodity

•• CultivarCultivar

•• Physiological agePhysiological age

•• Atmospheric compositionAtmospheric composition

•• TemperatureTemperature

•• DurationDuration

Which crop is most susceptible to damage by elevated CO2?

Which crop is most susceptible to damage by elevated CO2?

A. Asparagus

B. Sweet cherries

C. Lemon

D. Pear

A. Asparagus

B. Sweet cherries

C. Lemon

D. Pear

Tolerance to Low OxygenTolerance to Low Oxygen

0.5

1.0

2.0

3.0

5.0

0.5

1.0

2.0

3.0

5.0

Tree nuts, dried fruit & vegetables

Some cultivars of apples & pears, broccoli, most fresh cut F&V, mushrooms

Most cultivars of apples and pears, kiwifruit, peach, strawberry, cantaloupe, lettuce, cabbage

Avocado, persimmon, tomato, pepper, cucumber

Citrus, asparagus, potato, sweet potato

Tree nuts, dried fruit & vegetables

Some cultivars of apples & pears, broccoli, most fresh cut F&V, mushrooms

Most cultivars of apples and pears, kiwifruit, peach, strawberry, cantaloupe, lettuce, cabbage

Avocado, persimmon, tomato, pepper, cucumber

Citrus, asparagus, potato, sweet potato

Min. %O2 CommoditiesMin. %O2 Commodities

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Tolerance to Elevated Carbon DioxideTolerance to Elevated Carbon Dioxide

1

2

5

10

15

1

2

5

10

15

Some cultivars of apples (Fuji, Pink Lady, Braeburn)

Some apples & pears, apricot, pear, grape, tomato, lettuce, celery, artichoke

Some apples and pears, kiwifruit, peach, plum, orange, avocado, banana, cauliflower

Grapefruit, lemon, lime, persimmon, pineapple, cucumber, asparagus, broccoli

Strawberry, blueberry, raspberry, cherry, cantaloupe, sweet corn

Some cultivars of apples (Fuji, Pink Lady, Braeburn)

Some apples & pears, apricot, pear, grape, tomato, lettuce, celery, artichoke

Some apples and pears, kiwifruit, peach, plum, orange, avocado, banana, cauliflower

Grapefruit, lemon, lime, persimmon, pineapple, cucumber, asparagus, broccoli

Strawberry, blueberry, raspberry, cherry, cantaloupe, sweet corn

Max. %CO2 CommoditiesMax. %CO2 Commodities

How Does CA/MA How Does CA/MA Affect the Product?Affect the Product?

Oxygen( O2 )21%

+ SugarCarbon Dioxide

( CO2 )

Heat

RespirationRespiration

10

0%

25%

50%

75%

100%

2 4 6 8 10 12

% Oxygen

Res

pira

tion

Rat

e

Respiration and OxygenRespiration and Oxygen

If OIf O22 Conc. is too Low, Anaerobic Respiration will OccurConc. is too Low, Anaerobic Respiration will Occur

00 100100Percent Carbon DioxidePercent Carbon Dioxide

Rel

ativ

e R

esp

irat

ion

Rat

eR

elat

ive

Re

spir

atio

n R

ate

Effect of CO2 Level on Respiration RateEffect of COEffect of CO22 Level on Respiration RateLevel on Respiration Rate

The Commodity and Its EnvironmentThe Commodity and Its EnvironmentThe Commodity and Its Environment

Commodity:Commodity:Commodity:

*Respiration and ethylene production of commodity

*Natural dermal systemepidermis, cuticle, lenticels

*Additional barriers addedfilm wrapping, waxes, coatings

*Respiration and ethylene *Respiration and ethylene production of commodityproduction of commodity

*Natural dermal system*Natural dermal systemepidermis, cuticle, lenticelsepidermis, cuticle, lenticels

*Additional barriers added*Additional barriers addedfilm wrapping, waxes, coatingsfilm wrapping, waxes, coatings

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Package:Package:Package:

Permeability of packaging materialsVentilation openingsPlastic liners

Permeability of packaging materialsPermeability of packaging materialsVentilation openingsVentilation openingsPlastic linersPlastic liners


Storage room/transit vehicle:Storage room/transit vehicle:Storage room/transit vehicle:

*Degree of gas tightness*Ventilation systems*Atmosphere modification

*Degree of gas tightness*Degree of gas tightness*Ventilation systems*Ventilation systems*Atmosphere modification*Atmosphere modification

Must consider all barriersMust consider all barriersto gas exchange when to gas exchange when CA/MA is usedCA/MA is used

Commodity-Generated MAMethods to Restrict Gas Exchange

CommodityCommodity--Generated MAGenerated MAMethods to Restrict Gas ExchangeMethods to Restrict Gas Exchange

• Use of air-tight cold storage rooms• Waxes or other surface coatings• Use of polyethylene liners in shipping

containers• Packaging in film wraps or bags• Use of plastic package with diffusion

windows• Use of pallet covers• Manipulation of shipping container vents

•• Use of airUse of air--tight cold storage roomstight cold storage rooms•• Waxes or other surface coatingsWaxes or other surface coatings•• Use of polyethylene liners in shipping Use of polyethylene liners in shipping

containerscontainers•• Packaging in film wraps or bagsPackaging in film wraps or bags•• Use of plastic package with diffusion Use of plastic package with diffusion

windowswindows•• Use of pallet coversUse of pallet covers•• Manipulation of shipping container ventsManipulation of shipping container vents

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Produce Physiology

Converting/Filling TechnologyPolymer Engineering

Marketing/Consumer

MA Packaging

Produce Physiology Requirements/Characteristics

Produce Physiology Requirements/Characteristics

• Target Atmosphere• Temperature• Respiration Rate• Produce Type• Growing Region• Pre-Harvest Conditions• Postharvest Handling• Postharvest Processing• Desired Shelf Life

• Target Atmosphere• Temperature• Respiration Rate• Produce Type• Growing Region• Pre-Harvest Conditions• Postharvest Handling• Postharvest Processing• Desired Shelf Life

Modified Atmosphere PackagingModified Atmosphere Packaging

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Polymer Engineering RequirementsPolymer Engineering Requirements

• Target OTR (Oxygen Transmission Rate)

• Package Dimensions

• Package Style

• Product Weight

• Stiffness

• Optics

• Target OTR (Oxygen Transmission Rate)

• Package Dimensions

• Package Style

• Product Weight

• Stiffness

• Optics

Available as a copolymer in LDPE. Copolymer level can range from 2% to 28%. As the EVA

content increases, the stiffness decreases and the OTR increases.

Clarity also increases to about 6%, then decreases with higher EVA content.

EVA resins are blended with many of the above polymers to increase OTR, and improve seal properties.

600-900EVA Ethylene Vinyl Acetate resins

Manufactured with a metallocene catalyst. Similar to conventional linear PE’s with increased stiffness and clarity and improved seal properties.

480Metallocene Linear Low Density

Polyethylene

Plastomers are very soft and have low seal initiation temperatures and excellent hot tack strength.

Ultra Linear Low Density PE are PE’s manufactured with special metallocene catalysts. They have a very high OTR range.

1100Plastomer Metallocenes

Lower density provides increased OTR, clarity and decreased stiffness as compared to LDPE.

Low seal initiation temperature.

900ULLDPE Ultra Linear Low Density

Polyethylene

Increased stiffness, decreased clarity and OTR, as compared to LDPE.

350LMDPE Linear Medium Density Polyethylene

Stiffer and can be clearer than LDPE.480-500 depending upon gradeLLDPE Linear Low Density Polyethylene

Most commonly used polymer in the packaging industry.

Good stiffness and clarity.

450-500 rangeLDPE Low Density Polyethylene

CharacteristicsTypical OTR

(cc/100 in2/mil/atm/day)**

Material

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Blended with PE based polymers and EVA to achieve a peelable seal to itself

Polybutylene

Can be used in lidding material in combination with micro-perforation or high breathability patches. PET alone is a good oxygen barrier film. May be coated for various seal applications

5PET PolyethyleneterapthalatePolyester

Extremely stiff clear polymer that can be blended with polyethylene based polymers to increase stiffness without reducing clarity.

85-100COCCyclic Olefin Copolymer

Clear stiff polymer. Used predominately as the outer layer in fin and crimp co-extrusions.

500Styrene Butadiene Copolymer

Higher OTR than standard OPP achieved by proprietary manufacturing technology.

up to 600High Oxygen Transmission Rate Oriented Poly Poly Propylene (OPP)

Gauge ranges from 40 gauge (0.4 mil) to over 1 mil. Used as the outer layer in many produce laminations. Excellent stiffness and clarity.Often reverse printed, but it can be surface printed.

80-260Bi-Axially Oriented PP(BOPP)

Used commonly in core layers of co-extrusions. Good stiffness.

300PPPolypropylene

CharacteristicsTypical OTR (cc/100 in2/mil/atm/day)**Material

Multiple film layers are incorporated into a single structure during the manufacturing process to produce one film. See Figure 1 for an example of a coextruded film*.

Coextrusions

Different film types are joined together with some type of adhesive or molten polymer. See Figure 1 for an example of a laminated film.

Laminations

Different resins blended together to produce one mono-layer film. See Figure 1 for an example of a blended film.

Engineered Blended Mono Films

One resin one film (single layer).Monolayer Films

CharacteristicsStructure

•Recent advancements in Coextrusion technology have lead to a line of Coextruded films with OTR values up to 1500cc/100 sq. in. while at the same time providing excellent optics and increased stiffness

LDPE-EVA BlendLDPE-EVA Blend

LDPE

LDPE-EVALDPE-EVA Coextrusion Coextrusion

EVA

EVA

EVA

EVA

LLDPE

LDPE-EVA LaminationLDPE-EVA Lamination

Adhesive

Types of MAPackages

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Polyethylene Liner (1.5 mil) Delays Ripening of Bananas

Box liner for sweet cherries develops MA to reduce decay and keep stems green

Modified Atmosphere PackagingModified Atmosphere Packaging

••Injection of gasInjection of gas

••TwistTwist--tie or tie or zipzip--closing bagsclosing bagsworks fineworks fine

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Pallet Covers for Carbon Dioxide Treatment Pallet Covers for Carbon Dioxide Treatment of Strawberries during Transportof Strawberries during Transport

New Trends in PackagingNew Trends in Packaging

Controlled Atmosphere for StorageControlled Atmosphere for Storage

Capital investmentStore 2 to 12 monthsConstant monitoring of gas compositionSize room to market product quickly after openingMonitoring/sampling window

Capital investmentStore 2 to 12 monthsConstant monitoring of gas compositionSize room to market product quickly after openingMonitoring/sampling window

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Types of CA StorageTypes of CA StorageTypes of CA Storage

• Rapid CA– Establish in 1 to 3 days instead of 20 days

• Ultra low O2 CA• Sequential CA

– 2 wks 0.5% O2, then 2% O2 thereafter

• Dynamic CA– Harvest Watch (Satlantic) – chlorophyll

florescence– Ethanol monitoring system (ATO,

Netherlands)

• Rapid CA– Establish in 1 to 3 days instead of 20 days

• Ultra low O2 CA• Sequential CA

– 2 wks 0.5% O2, then 2% O2 thereafter

• Dynamic CA– Harvest Watch (Satlantic) – chlorophyll

florescence– Ethanol monitoring system (ATO,

Netherlands)

Portable, Low-Cost Tent for Controlled Atmospheres or Modified AtmospherePortable, LowPortable, Low--Cost Tent for Controlled Cost Tent for Controlled Atmospheres or Modified AtmosphereAtmospheres or Modified Atmosphere

Courtesy, Nate ReedCourtesy, Nate Reed

Sources of Nitrogen for CA/MA-Nitrogen is used to replace Oxygen-

Sources of Nitrogen for CA/MASources of Nitrogen for CA/MA--Nitrogen is used to replace OxygenNitrogen is used to replace Oxygen--

• Liquid nitrogen

• Pressure swing adsorption (PSA) separators

• Membrane separators (Generon, Permea)

•• Liquid nitrogenLiquid nitrogen

•• Pressure swing adsorption (PSA) Pressure swing adsorption (PSA) separatorsseparators

•• Membrane separators (Membrane separators (GeneronGeneron, , PermeaPermea))

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Atmospheric Air

N2O2, CO2

Membrane Air SeparatorMembrane Air Separator

Courtesy Maersk SealandCourtesy Courtesy MaerskMaersk SealandSealand

Equipment for Carbon Dioxide Removal

Equipment for Equipment for Carbon Dioxide RemovalCarbon Dioxide Removal

• Absorbers– Water

– Sodium hydroxide

– Ethanolamine

– Hydrated lime

• Adsorbers– Activated charcoal

– Membrane sieves

•• AAbbsorberssorbers–– WaterWater

–– Sodium hydroxideSodium hydroxide

–– EthanolamineEthanolamine

–– Hydrated limeHydrated lime

•• AAddsorberssorbers–– Activated charcoalActivated charcoal

–– Membrane sievesMembrane sieves

25 to 30 lbs.fresh hydrated limeper ton of apples

Can also be placed in aseparate room outside of the CA room

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Use of CA for Long Term Storage

Avocado, olive, some cultivars Avocado, olive, some cultivars of peach, plum, nectarine, of peach, plum, nectarine, persimmon, pomegranatepersimmon, pomegranate

1 1 -- 33

Cabbage, Cabbage, chinesechinese cabbage, cabbage, kiwifruit, some cultivars of kiwifruit, some cultivars of asianasian pearspears

3 3 -- 66

Some cultivars of apples and Some cultivars of apples and pearspears

6 6 -- 1212

Nuts and dried fruits and Nuts and dried fruits and vegetablesvegetables

>12>12

CommoditiesCommoditiesMonths of StorageMonths of Storage

Use of CA for Short Term Storage

Asparagus, broccoli, lettuce, Asparagus, broccoli, lettuce, sweet corn, fresh herbs, fresh sweet corn, fresh herbs, fresh cutcut

Delays senescence Delays senescence & compositional & compositional changeschanges

Blackberry, blueberry, cherry, Blackberry, blueberry, cherry, fig, grape, raspberry, strawberryfig, grape, raspberry, strawberry

Controls decayControls decay

Avocado, mango, banana, Avocado, mango, banana, melon, nectarine, papaya, melon, nectarine, papaya, peach, plum, tomato (MG, RR)peach, plum, tomato (MG, RR)

Delays ripening and Delays ripening and avoids chilling avoids chilling injuryinjury

CommoditiesCommoditiesBenefitsBenefits

Use of CA/MA During TransportUse of CA/MA During Transport

• Can make ocean transport a viable alternative to airfreight

• Within a retail or consumer package• Polymeric film liner within a carton• Within a plastic film cover for a pallet• In a rail car• In an intermodal container• Within a refrigerated storage compartment

aboard ship

• Can make ocean transport a viable alternative to airfreight

• Within a retail or consumer package• Polymeric film liner within a carton• Within a plastic film cover for a pallet• In a rail car• In an intermodal container• Within a refrigerated storage compartment

aboard ship

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Examples of CA ShipmentsExamples of CA Shipments

• Avocados from Mexico to Japan and Hong Kong

• Blueberries from Chile to US

• Mangos from Indonesia to Middle East

• Stone fruits from US to Taiwan

• Papayas from Taiwan to Canada

•• Avocados from Mexico to Japan and Hong Avocados from Mexico to Japan and Hong KongKong

•• Blueberries from Chile to USBlueberries from Chile to US

•• Mangos from Indonesia to Middle EastMangos from Indonesia to Middle East

•• Stone fruits from US to TaiwanStone fruits from US to Taiwan

•• Papayas from Taiwan to CanadaPapayas from Taiwan to Canada

CA Unit for Break Bulk Loads in Ship HullsCA Unit for Break Bulk Loads in Ship Hulls

Temperature ControlTemperature ControlControlled AtmosphereControlled Atmosphere

Humidity ControlHumidity ControlHumidity Control


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AIRAIRAIRN2

CO2O2

Ethylene ScrubberEthylene ScrubberEthylene Scrubber

O2 +CO2

OO22 ++COCO22

Membrane Air SeparatorMembrane Air Membrane Air SeparatorSeparator

C2H4

Pressure release valvePressure release valvePressure release valve


Normal Air

Normal Normal AirAir

O2 - 21%OO22 -- 21%21%

CO2 - 0.03%COCO22 -- 0.03%0.03%

Typical desired

atmosphere

Typical Typical desired desired

atmosphereatmosphere

O2 - 3%OO22 -- 3%3%

CO2 - 5%COCO22 -- 5%5%

StarfreshStarfreshStarfreshO2 decreases to setpoint and is maintained by product respiration and sped up and controlled by purging N2 into the unit

OO22 decreases to setpoint and decreases to setpoint and is maintained by product is maintained by product respiration and sped up and respiration and sped up and controlled by purging Ncontrolled by purging N22 into into the unitthe unit

CO2 increases from product respiration and can be further increased by adding CO2 if necessary

COCO22 increases from increases from product respiration and product respiration and can be further can be further increased by adding increased by adding COCO22 if necessaryif necessary


Installation of curtain in a CA container. Dry ice is used to

elevate the CO2 level.

Installation of curtain in a CA Installation of curtain in a CA container. Dry ice is used to container. Dry ice is used to

elevate the COelevate the CO22 level. level.

Dry ice Dry Dry ice ice


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APL System - Gas flushing

Required gas concentration is quickly achieved by gas flushing

Courtesy APL

Installation of Controller in Air Exchanger

MaxTend – Controller and valve externally mounted

Courtesy APL

CO2 Scrubber - APL

CO2 scrubbers

are packed in a

protective carton

If necessary CO2 scrubbersare placed onthe top of the load

Courtesy APL

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Curtain Installation

A Curtain is installed across the door to minimize leakage

Courtesy APL

Asparagus CA graph

Courtesy APL

Flush with N2Absorb CO2 with Lime

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How it Works – Marine CA

Marine PresentationLink

http://www.transfresh.com/m_how.html

True or False?

Use of CA/MA Can Replace the Need for Good Temperature Management

True or False?

Use of CA/MA Can Replace the Need for Good Temperature Management

• True

• False

• True

• False

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Questions?Questions?

mitcham-modified controlled atmospheres short course...

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