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Postharvest Quality and Physiology of ‘Fuji’ ApplesSubjected to Phytosanitary IrradiationNasim KheshtiChapman University, khesh100@mail.chapman.edu

Alan BaqueroChapman University, baque101@mail.chapman.edu

Anderson MeloChapman University, melo@chapman.edu

Anuradha PrakashChapman University, prakash@chapman.edu

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Recommended CitationKheshti, Nasim; Baquero, Alan; Melo, Anderson; and Prakash, Anuradha, "Postharvest Quality and Physiology of ‘Fuji’ ApplesSubjected to Phytosanitary Irradiation" (2017). Student Research Day Abstracts and Posters. 232.http://digitalcommons.chapman.edu/cusrd_abstracts/232

Postharvest Quality and Physiology of ‘Fuji’ Apples subjected to

phytosanitary Irradiation

Kheshti, N., Baquero, A., Melo, A., Prakash, A.

Introduction

In the state of California, apples are harvested almost

a month before Washington’s apple harvest, therefore,

California has a time advantage in exporting apples

overseas. However, quarantine restrictions require

that California apples either be fumigated with methyl

bromide or be kept at 0˚C for 40 days or at 3.3 ˚C for

90 days to prevent spread of of Light Brown Apple

Moth and Oriental fruit moth (1, 2). Both treatments

have some disadvantages. Methyl bromide is ozone

depleting and with cold treatment, California loses its

time advantage in comparison to Washington state.

Irradiation is an effective treatment to sterilize and

destroy insect pests on apples and was recently

approved for apples exported to Mexico from

California (3). However, the impact on quality and

shelf of the apples is not known.

ObjectiveTo investigate the influence of the irradiation on

physicochemical properties of Fuji apples after

harvest and compare the quality of irradiated apples

with those treated with cold storage and fumigation.

The specific goals are to:

1. Determine the tolerance of apples to irradiation at

400 and 800 Gy.

2. Conduct a comparative evaluation of irradiated,

fumigated, and cold treated apples

Experimental Method

Results and Discussion Results and Discussion (cont.)

Irradiation caused an immediate decrease in

firmness by 12% at 400 Gy and by 38% at 800 Gy; this

difference remained throughout storage.

Electrolyte leakage was higher (P<0.05) in the 800

Gy apples as compared to control and 400 Gy.

Irradiation initially elevated respiration rate by 27%

at 800 Gy and 15% at 400 Gy. During storage at cold

temperature there was no significant difference between

control and 400 Gy while 800 Gy continued to be

significantly higher.

Ethylene decreased by 29% at 800 Gy and 18% at

400 Gy one day after treatment. During storage at room

temperature, ethylene levels increased significantly in the

control and 400 Gy, and remained constant and

significantly lower at 800 Gy.

ConclusionsThe increase in respiration rate was not reflected in most

of the quality parameters measured. The impact on

firmness and electrolyte leakage on quality perception

needs to be corroborated with sensory tests.

Future Study

Further studies on impact of irradiation on enzyme

activities such as PAL and PME would be helpful to

understand the basis of changes in respiration rate and

firmness. It would also be beneficial to study the effect of

maturity stage on irradiated fruit quality.

Acknowledgements

I would like to thank Dr. Anuradha Prakash for her

continued support and patience in guiding us through

this project and USDA-FAS for funding this project, Prima

Fruitta for providing the apples and Steri-tek for radiation

treatment. We are grateful to Todd Sanders of the

California Apple Commission for his technical assistance.

References

1. Lynch B. 2010b. Apples Industry and trade summary.

Washington: Office of Industries.

2. USDA. 2016. Treatment Manual. Non-Chemical

Treatment.

3. Phytosanitary Export Database. 2016 Available from:

https://pcit.aphis.usda.gov/PExD/faces/ViewPExD.jsp.

Apples sourced from a single farm were obtained from adistributor and shipped to a electron beam irradiationfacility where they were irradiated at 0, 400, 800 Gy.

Apples kept 7 days in cold temperature for simulating therefrigerated transportation of the apples from California toMexico. Then, the apples were placed in ambienttemperature for 7 days in order to simulate the retailcondition.

Statistical Analysis :

Linear fixed models and linear mixed models (R statistical software)

Figure 3. Firmness of the apples during storage- Irradiation

decrease firmness.

Figure 7. Peroxidase enzyme activity during storage time

Figure 4. Electrolyte Leakage of the apples during

storage. Irradiation increase EL.

Irradiation:

Freshly harvested apples, washed, waxed,

boxed, cooled

Refrigerated transport to Chapman University

Refrigerated transport to irradiation facility

Control 250 Gy

Baseline analysis upon arrival at CU

Analysis with fresh tissue

Respiration rate/Ethylene (every two days)

Starch iodine test

Color (sensory/instrumental)

Texture (Firmness)

Electrolyte Leakage

Quality indices (TSS/TA)

Damage, decay

1 week at ambient temperature

Analysis with frozen tissue (-80 ºC) Irradiated fruit only

Malondialdehyde (MDA)

Total phenolics

Organic Acids

Sugars

Cell wall degrading enzyme (PME)

Cold treated: Washed, waxed, cooled, O-1

C storage for 40 daysMeBr: Freshly harvested apples

washed, waxed, boxed, fumigated,

cooled

Refrigerated for 1 week

1000 Gy

Shikimic acid in treated apples during storage

Ctrl 400 Gy 800 Gy Ctrl 400 Gy 800 Gy Ctrl 400 Gy 800 Gy

Shik

imic

(µg/

g F

W)

0

1

2

3

4

5

6

7

One Day After Treatment

Day 7

Day 14

a b b a ab ba aa

POD Enzyme Activity During Storage Time

Ctrl 400 Gy800 Gy Ctrl 400 Gy800 GyCold trt Ctrl 400Gy800 GyCold trt

POD(

A/m

in)

Ctrl

400 Gy

800 Gy

Ctrl

400 Gy

800 Gy

Cold trt

One day after treatmentt

Day 7

Day 14

aab a

a a a aab b a

b

Figure 1. Respiration rate of the apples during storage.

Irradiation increase respiration rate.

Figure 5. Internal view of different treated apples. No

difference in browningFigure 6. Browning index of different treated apples

during storage time. No significance difference

400

800

Figure 8. Shikimic acid during storage time.

Chemical Analysis

Ctrl

400GY

800Gy

Ele

ctr

oly

te L

eak

ag

e

0 7 14

Storage Time (Day)

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400GY

800Gy

0 2 4 7 9 11 14

Storage Time (Day)

Ctrl

400GY

800Gy

Storage Time (Day)

0 2 4 7 9 11 14

a

bc

a

b

c

Figure 2. Ethylene production rate during sorage-

Iradiation decrease ethylene production rate.