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
11
38
53
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
Tem
pe
ratu
re (
°F)
Control Ambient MeBr Ambient IRR Ambient
Grading
0
1
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6
0 1 3 5
Control MB IR
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% Decay
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Control MB IR
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
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