Phytosanitary irradiation: quality impacts on … irradiation: quality impacts on blueberries and cherries ANURADHA PRAKASH. Study objectives •Dose response studies to determine

Phytosanitary irradiation: quality impacts on blueberries and cherries

ANURADHA PRAKASH

Study objectives

•Dose response studies to determine tolerance of fruit to phytosanitaryirradiation

•Determine the effects of distribution and retail conditions

•Compare irradiation to conventional treatments

2

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)

1. Dose response study

Blueberries treated with irradiation up to 800 Gy

Stored for 26 days

4

Sensory Evaluation

Nine panelists trained in 6 sessions to determine changes in quality attributes.

During evaluation they used 15cm unstructured scales 0-15 or none-to-intense.

Consumer testing with approx. 100 untrained consumers using 9 point

Hedonic scales

Analytical Measurement

Titratable Acidity, Brix

Texture: Firmtech & TA-XTPlus Texture

Analyzer

Color: Konica Minolta Spectrophotometer 2500d

Statistical Analysis

Linear fixed models and linear mixed models

(R statistical software)

Blueberry Trained panel

↓ Mouth Firmness

↓Touch Firmness

↓Flavor

800 Gy

↓Smoothness

↓Skin Firmness

Age

Analytical Analysis- Kramer Shear

0

100

200

300

400

0 0.4 0.6 0.8

Day 12

Day 26

Forc

e N

Dose (kGy)

There was a significant difference (p≤0.05) in texture between control and irradiated samples.

Blueberry Consumer Evaluation

6.466.85 a

6.42

5.82 b

1

2

3

4

5

6

7

8

9

Day 12 Day 26

Text

ure

6.526.82 a

6.39 6.25 b

1

2

3

4

5

6

7

8

9

Day 12 Day 26

0 kGy

0.8 kGy

Ove

rall

Lik

ing

Overall Flavor and Appearance Liking were

not affected by irradiation

Dose response study conclusionsBlueberries have a good tolerance to irradiation

Softening detected using instruments and trained panels

Consumer acceptance affected at doses >700 Gy

Weight loss, % decay, color, bloom not affected by irradiation

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Combination with MAPIrradiation is an effective phytosanitarytreatment

MAP has been shown to retain blueberry quality◦ Slower rates of ripening◦ Growth of aerobic spoilage microorganisms and oxygen-

dependent pests inhibited◦ Limits moisture loss◦ Longer product shelf-life

Combination treatment?

2. The effects of modified atmosphere packaging and irradiation on the quality of blueberries under simulated commercial transportation and retail conditions

Star varJune 2012

Jewel varJuly 2012

Snowchaser varSeptember 2012

Harvest

Control Irr MAP IMAP

Arrive at Chapman – Preship Test

4-7 days

Air Shipment Simulation @ 4 °C (1 day)

Storage (3 day) @ 20°C

Quality Assessment

Ground Shipment Simulation @ 4 °C (8 day)

Storage (3 day) @ 20°C

Quality AssessmentSea Shipment Simulation @ 4 °C

(21 day)

Storage (3 day) @ 20°C

Quality Assessment

Postharvest Treatments

MAP applied about ~18 hrs before irradiationTarget dose: 0.4 kGyReceived up to 0.8 kGy

Effect of distribution and retail conditions

Different varieties/seasons of the same fruit can exhibit varied responses to irradiation

Blueberry firmness

Decay

Sea

Ground

Control IRR MAP IMAP

Effect of modified atmosphere packaging

Weight

Jewel variety - Sensory

Overall Liking Texture Appearance Flavor

Treatment

Air Simulation

Ground Simulation

Sea Simulation

Air Simulation

Ground Simulation

Sea Simulation

Air Simulation

Ground Simulation

Sea Simulation

Air Simulation

Ground Simulation

Sea Simulation

Jewel

Control 6.7±0.2ax 6.1±0.1ay 4.8±0.2cz 6.8±0.2ax 6.3±0.1by 5.2±0.2bz 7.4±0.1ax 7.0±0.1ay 6.3±0.2bz 6.7±0.2ax 6.2±0.1ay 5.1±0.2bz

IRR 6.8±0.3ax 6.5±0.3ay 5.8±0.6bz 6.9±0.2ax 6.5±0.3aby 5.8±0.5bz 7.4±0.2ax 7.1±0.3ay 6.4±0.5bz 6.8±0.3ax 6.5±0.3ax 6.0±0.6ax

MAP 6.4±0.3ax 6.4±0.3ax 6.6±0.6ax 6.7±0.2ax 6.7±0.3ax 6.7±0.5ax 7.0±0.2ax 7.1±0.3ax 7.3±0.5ax 6.4±0.3ax 6.4±0.3ax 6.6±0.6ax

IMAP 6.6±0.3ax 6.5±0.3ax 6.4±0.6ax 6.5±0.2ax 6.5±0.3abx 6.6±0.5ax 7.1±0.2ax 7.1±0.3ax 7.2±0.5ax 6.7±0.3ax 6.5±0.3ax 6.2±0.6ax

Texture Appropriateness (JAR Scale)Treatment

Air Simulation

Ground Simulation

Sea Simulation

JewelControl 2.7±0.1ax 2.4±0.0by 2.0±0.1bzIRR 2.7±0.1ax 2.6±0.1aby 2.3±0.2bzMAP 2.8±0.1ax 2.7±0.1ax 2.6±0.2axIMAP 2.5±0.1ax 2.6±0.1abx 2.7±0.2ax

Significant decreases in Control and IRR over time

Maintenance of higher scores over time in MAP and IMAP

3. 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

4 d

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

Yeast and mold

Control Irr MB MAP IMAP MBMAP

Treatments

Day

11

38

53

Consumer-Overall Liking

Salmonella survival in blueberries

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0 7 14 21 28

Log

Val

ue

of

CFU

/g

Days

Control Irradiated

Sweet Cherries

❖ Sweetheart: July and August, 2013, Washington

❖ 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

Bag in the box, LDPE (Freshlok, Yakima, WA)

Firmness-Kramer Shear

Sensory-appearance

Damage

Consumer-Overall liking

Control Irradiation

MB

MAP

IMAP MBMAP

Trial 2, Day 27

Sweet Cherries-conclusions◦Shelf life of 4-5 weeks before showing significant signs of quality loss

◦Harvest season is a significant factor

Overall Results

• Irradiation preserves quality better than MeBr• MAP helps maintain quality• Cannot easily generalize responses of all fruit• Varietal and maturity differences

Quality is highly dependent on:Initial qualityGas concentrations Temperature

Harvest date

Next steps•Optimize MAP

•Evaluate influence of harvest date during the season

•Assess intra-year variations

•Conduct commercial sea and air shipment tests of irradiated fruit

Acknowledgments

Jonathan TongKaren ThangKimberlee AuSheila LeeVikalp Joisar

USDA-APHISU.S. Highbush Blueberry CouncilSadexNutek CorporationApio IncVeg-Fresh FarmsSodexo

Anuradha Prakash

[email protected]

(714) 744-7826

Consumer Acceptance

•Consumers respond positively when informed

•People buy irradiated food

•Insect quarantine applications with produce are expected to grow

•Focus on the product and its benefits, rather than the technology

•Most (but not all) will buy when given the opportunity