Effect of Irradiation on Fruit Quality

Anuradha Prakash

Chapman University

Outline

• Quality considerations

• Effects of phytosanitaryirradiation on fruit

• Research on blueberries

• Cherries to Vietnam

Phytosanitary Irradiation of Fruit• Cold treatment

• Phytosanitary doses are low!

• Quality dependent on• Extrinsic factors:

• Dose

• Temperature

• Atmosphere/Packaging

• Handling

• Intrinsic factors: • Variety and cultivar

• Maturity stage

• Climacteric versus non-climacteric

• Composition

Most fruit can be irradiated between 150-600 Gy with no adverse effects on quality

Sugraone Crimson Red

Foods 2015, 4, 376-390; doi:10.3390/foods4030376

Courtesy Marissa Wall, 2012,USDA ARS, Hawaii

Ethylene and Ripening

Courtesy Marissa Wall, 2012USDA-ARS, Hilo, Hawaii

Irradiation- an abiotic stress

Effect of irradiation on climacteric fruit

Delay in ripening• Banana

• Papaya

• Mango

• Pear

• Treatment of immature fruit- greater delay of ripening

• Treatment of mature fruit- better quality

• Temperature of storage is very important

Acceleration of ripening

• Peaches

• Nectarines

- Increased respiration rate

J Sci Food Agric 80:1169±1175 (2000)

Control 0.8 kGy

- Delayed ripening

http://biology-forums.com/gallery/18099_27_04_12_6_29_54.jpeg

-Acceleration of ripening-Softening

- Phenolic biosynthesis

http://www.mdpi.com/2077-0472/2/3/259/htm

Day 1 after irradiation

4 weeks

3 weeks

Control 150 Gy 1000 GyChandler pummelos

Differences among varieties

Dr. Edmundo Mercado Silva

Post harvest decay

• Inhibition of fungal rot requires doses >1.5 kGy

• At these dose levels, most fruit show negative impacts on quality• Softness

• Undesirable flavors

• Altered metabolism and ripening

• Combination treatments may help• Hot water dips

• Fungicides

• Controlled/modified atmospheres

TASC Grant Quality Study objectives

• Dose response studies to determine tolerance of fruit to phytosanitary irradiation

• Determine the effects of distribution and retail conditions

• Compare irradiation to conventional treatments

19

Comparing irradiation and methyl bromide fumigation in combination with MAP

Harvest

Chapman University

MeBr FumigationIrradiation

Control Irradiation MAP MB IMAP MBMAP

Analytical and Sensory Testing Weekly

Statistical Analysis

Blueberries

• Climacteric fruit

• Average Shelf-life: 2 weeks

• Optimum Conditions: • Temperature: 31-32°F

• Relative Humidity: 90-95%

• Controlled Atmosphere: 10-15% CO2 and 1-10% O2

• Top-quality Blueberries:• Free from damage & physical defects

• Free from mold growth (Botrytis and Rhizopus rot)

Treatment conditions

❖ Bluecrop: July and August, CA

❖ Fumigation: Global Pest Management (Long Beach, CA)➢ 21.1°C

➢ 2 h at 32 g/m3

➢ Degas for 4-5 h

❖ Gamma Irradiation: Sterigenics (Tustin, CA)➢ Target dose: 400 Gy

MAP BreatheWay® Membrane MAP bags, (Apio, Inc., Guadalupe,

CA)

Firmness-Kramer Shear

Damage and Physical Defects

Control Irr MB MAP IMAP MBMAP

Treatments

Day

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38

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Consumer-Overall Liking

Sweet cherries to Vietnam

Air freighted to

Ho Chi Minh City

Unwrapped, ambient temperature retail

display

Quality evaluation

MeBr15.56 °C and 32g/m3 for 3.5 hours

Forced air cooled to

1°C

IrradiationForced air cooled to

1°C

Gamma

400 Gy

Control Maintained cold

Freshly harvested Washington sweet cherries, trucked to Los Angeles

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Transportation Day 1 Day 2 Day 3 Day 4 Day 5

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Control Ambient MeBr Ambient IRR Ambient

Grading

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Control 400 Gy Fumigated

Overall Results

• Cannot easily generalize responses of all fruit

• MAP helps maintain quality• Irradiation preserves quality

better than MeBr• Shelf-life may or may not be

better than non-treated fruit

Considerations for tradeof irradiated produce

• Fruit varieties

• Initial quality

• Maturity at harvest

• Handling

• How is the fruit packed?

• Where is the product exported to?• How long does it take? • Shipping, distribution

and retail conditions

Challenges to use of phytosanitary irradiation

• Maintaining cold chain – true for any treatment

• Conventional treatments still in use

• Location of irradiation facilities

• Added cost

• Regulatory hurdles

• Willingness of retail outlets to carry irradiated fruit

Gracias!

Anuradha Prakash

Professor and Program Director

Chapman University

(714) 744-7826

prakash@chapman.edu