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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
THANK YOU