Effect of Chilling on Cucumber Postharvest Quality

EFFECT OF CHILLING ON POSTHARVEST QUALITY OF

CUCUMBER

Postharvest 2012

CUCUMBERCUCUMIS SATIVA

• Family: Cucurbitacaea(Cucurbit Family)

• Vining Habit

• Plasticulture

• Fresh Market and Canning

• Harvested immature

http://msue.anr.msu.edu/news/managing_plastic_mulches_profitably

POSTHARVEST CONSIDERATIONS

Non-climacteric

Low respiration rates

Chilling Sensitive

Highly sensitive to ethylene

Can be held in CA conditions

Optimum Conditions: 10-12.5°C; 95% RH

UC Davis Postharvest Technology Department

http://postharvest.ucdavis.edu/pfvegetable/Cucumber/

OBJECTIVES

(1)

Determine the effect of chilling temperatures on

cucumber respiration and ethylene production

(2)

Determine the effect of storage time at chilling

temperatures on cucumber quality

MATERIALS AND METHODSEXPERIMENTAL DESIGN

• Split Plot Design

• Treatments:• 3 Temperatures (12°C, 7.5°C, and 5°C)

• 2 Storage Lengths (6 and 10 Days)

• 3 Replications• 1 fruit per replication

• Cultivar: ‘Dasher’

TIME TABLE

Action Date

Harvest Oct -22 Monday

Begin Experiment Oct -23 Tuesday

Initial Respiration Oct –24 Wednesday

Respiration and Ethylene Reading

1

Oct –29 Monday (6 days)

Quality Ratings 1 Oct -30 Tuesday

Respiration and Ethylene Reading

2

Nov -2 Friday (10 days)

Quality Ratings 2 Nov -3 Saturday

MATERIALS AND METHODSSAMPLE PREPARATION

1. Field harvested

2. Washed (100 ppm bleach solution)

3. 18 were sorted by size

4. Each group was weighed

5. 2 groups of 3 went into its respective temperature

MATERIALS AND METHODSRESPIRATION AND ETHYLENE

1. Individual cucumber weighed and recorded

2. Placed into open jar

3. Jars moved to 20°C in the AM

4. Jars sealed at 6 and 10 hrs.

5. 1 measurement was taken from each jar

6. Gas was analyzed using a gas chromatograph

Gas Measurement

Process1

32

MATERIALS AND METHODSQUALITY ASSESSMENT

1. Samples held at 20°C for 24 hrs.

1. Weight was measured

2. Injury was assessed

3. Cucumbers Sliced for Interior Comparison

% CO2 CO2 Rate (ml CO2/ kg-hr)

Ethylene Content(ppm)

Ethylene Rate (μl C2H4/kg-hr)

Both measured at 6 and 10 hours

after transfer

MATERIALS AND METHODSMEASUREMENTS

Objective 1

Respiration and Ethylene

Objective 2

Quality Assessment

Interior and Exterior Injury

Scale of 1-5(Mercer and Smittle 1992)

Cumulative Weight

Before and After

MATERIALS AND METHODSANALYSIS

Analyzed using Two Way ANOVA

Means separated using Duncan's Multiple Range

Test

RESULTS

RESULTSRESPIRATION BY TEMPERATURE

22

23

24

25

26

27

28

29

30

5 7.5 12

Re

spira

tio

n R

ate

(m

l C

O2/

kg

-hr)

Temperature (°C )

ab

b

a

1

α=0.05

RESULTSETHYLENE BY TEMPERATURE

0

0.5

1

1.5

2

2.5

3

3.5

5 7.5 12

Eth

yle

ne

Ra

te (

μl C

2H

4/k

g-h

r)

Temperature (°C )

a

b

b

α=0.05

RESULTSRESPIRATION BY TIME

0

5

10

15

20

25

30

35

40

6 hours 10 hours

Re

spir

atio

n R

ate

(m

l C

O2/

kg

-hr)

Time After Transfer

b

aα=0.05

RESULTSETHYLENE BY TIME

0

0.5

1

1.5

2

2.5

3

6 Hours 10 Hours

Eth

yle

ne

Ra

te (

μlC

2H

4/k

g-h

r)

Time after Transfer

a

a

α=0.05

RESULTSQUALITY ASSESSMENT

Injury was

observed at

levels from 1-4

1 4

RESULTSQUALITY ASSESSMENT- EXTERIOR

RESULTSQUALITY ASSESSMENT- INTERIOR

No observable differences at any temperature

CONCLUSIONS

Cucumbers held below 7.5°C will increase respiration

Cucumbers held at 5°C will exhibit much greater ethylene production

Cucumbers allowed to rest for >10 hours at 20°C will have greater respiration

Cucumbers held for 10 days at 5°C will result in poor exterior quality

Exposing cucumbers to chilling temperatures will increase weight loss

CONCLUSIONSCONSUMER AND INDUSTRY

Cucumbers should be stored at about 12°C for optimum storage and quality

Continued exposure to chilling temperatures effects quality

Warmer temperatures may be detrimental to the fruit

Exterior quality does not necessarily dictate the interior quality

Q U E S T I O N S O R S U G G E S T I O N S A R E W E L C O M E D

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