1

Leafy VegetablesBroccoli, Cauliflower, Celery,

Asian Leafy

Marita Cantwell, UC Davismicantwell@ucdavis.edu

http://postharvest.ucdavis.eduPostharvest Technology Short Course, June 2009

Causes of Quality & Postharvest LossesCauses of Quality & Postharvest Losses

Leafy VegetablesLeafy VegetablesLettucesLettucesSpinachSpinachCabbageCabbageChardChardBroccoliBroccoliCeleryCeleryHerbsHerbsEndivesEndivesAsparagusAsparagusGreen OnionsGreen Onions

Water lossWater loss Mechanical damageMechanical damage Loss of chlorophyll and Loss of chlorophyll and

other nutrientsother nutrients Respiration ratesRespiration rates Microbial growthMicrobial growth Sensitivity to ethyleneSensitivity to ethylene

2

Relative Perishability

Relative Respiration Rate

NutsNutsDatesDates

CitrusCitrusGarlicGarlicPotatoPotato

AppleAppleCarrot Carrot OnionOnion

BananaBananaTomatoTomatoPeachPeach

ArtichokeArtichokeBroccoliBroccoliStrawberryStrawberry

AsparagusAsparagusPeasPeasSweet CornSweet Corn

10

Top Antioxidant foodsTop Antioxidant foods

VVVEEEGGGEEETTTAAABBBLLLEEESSS ORAC* units per 100 g**

Kale 1,770 Beets 840

Spinach 1,260 Peppers, red 710

Brussel sprouts 980 Onion 450

Alfalfa Sprouts 930 Corn 400

Broccoli florets 890 Eggplant 390*

* Oxygen Radical Absorbance Capacity** 100 g = about 3.5 ouncesAgricultural Research, USDA, Feb 1999

Impact of PostharvestConditions?

3

21.8

17.7

16.9

15.9

11.0

Chroma

Color Value

49.8

47.1

45.9

43.3

42.0

L

Color

Value

5.016.5115.35

5.517.5123.34

5.824.4125.43

6.428.2127.52

7.334.1135.01

Total Carotenoidsmg/100g FW

Total Chlorophyll mg/100g FW

Hue

Color

Value

Yellowing

Score

11

Broccoli Color Rating Scale andCorresponding Color Values andPigment Concentrations.

Date average of 3 replicates at each color stage

3

2

5

4

Broccoli CompositionBroccoli Composition

Sugar Chlorophyll Carotene Ascorbic Ac.

% mg % mg % mg %

2 150 11 42

1 23 4 34

2 8 1 40

3 4 1 26

LeavesLeaves

FloretsFlorets

BranchesBranches

Stalk Stalk

Data on fresh weight basis Data on fresh weight basis Cantwell, unpublishedCantwell, unpublished

4

cm

6

7

8

9

10

11

%

5

6

7

8

9m

g/g

FW

21

24

27

30

33

36

39

42

µg

/g F

W

6

8

10

12

14

16

18

µg

/g F

W

0

1

2

3

4

5

6

7

mg/

100

g F

W

70

80

90

100

110

120

130

Pounds Total N Pounds Total N

E. Carotenoids F. Ascorbic Acid

D. ChlorophyllC. Sugar

B. Dry weightA. Head diameter

60 120 180 240 300 60 120 180 240 300

Nitrogen fertilization Nitrogen fertilization significantly affectssignificantly affectsbroccoli head size and broccoli head size and CompositionComposition

Excessive N fertilizationExcessive N fertilizationreduces shelfreduces shelf--life oflife ofbroccoli at 5broccoli at 5°°C (41C (41°°F)F)

Lestrange & Cantwell, 1997, 2001, 2002

Storage temperature

Day

s

(to

init

iate

yel

low

ing

)

0

5

10

15

20

25

30

35 Broccoli Shelf-life & Temperature

032

2.536

541

7.545

1050

12.5 55

1559

20°C68°F

cv. Legacy

Fresh appearance

Green florets

Tender stem

No discoloration

No breakage

No decay

No off-odors

5

0ºC 5ºC10ºC

15ºC 20ºC

7 daysm

g/10

0 g

FW

0

5

10

15

20

25

mg/

100g

FW

0

1

2

3

4

Days

0 5 10 15 20 25

mg/

100

g F

W

0

5

10

15

20

25

30

35

40

Days

0 5 10 15 20 25

mg/

100

gFW

0

5

10

15

20

25

Chlorophyll Carotenoids

Ascorbic Acid Sugars

0°C (32°F)10°C (50°F)

20°C (68°F)

Limit of Salability

Broccoli Shelf-life: changes in composition

(Cantwell, unpublished)

6

Iceless BroccoliTemperatureMoisture loss

• 0°C with very high humidity

• MA: 5-8% O2 + 7-10% CO2

Broccoli Storage Conditions

Delay to Cool, hours at 25°C (77°F)

0 3 6 9 12 15

Day

s to

yel

low

at

7.5°

C (

45°F

)

0

2

4

6

8

10

12

14

16

Broccoli, cv. Marathon

Impact of cooling delays Impact of cooling delays on shelfon shelf--life (yellowing)life (yellowing)

• Impact of coolingImpact of coolingdelays on stem texturedelays on stem texture& firmness of heads?& firmness of heads?

•• Best cooling method?Best cooling method?•• Subsequent water loss?Subsequent water loss?

Alternatives to Alternatives to use of iceuse of ice

7

Broccoli ShelfBroccoli Shelf--life & Varietylife & Variety

Days 7.5°C Score 2

Cultivar Range Average % Head Rot PPPaaaccckkkmmmaaannn 111777---111999 111777...777 333333

LLLiiibbbeeerrrtttyyy 111222---111777 111555...111 000

PPPaaatttrrriiiooottt 111222---111777 111444...444 111000

GGGrrrnnn VVVaaallliiiaaannnttt 111333---111555 111444...111 000

BBBrrriiigggaaadddiiieeerrr 999---111222 111111...222 222000

MMMaaajjjeeessstttiiiccc 999---111444 111111...111 111111

AAAvvveeerrraaagggeee 111222---111555 111333...777 111111

M. Cantwell, Nov 1997

BacterialSoft rot

8

Chlo

roph

yll,

mg/g

FW

0.3

0.4

0.5

0.6

0.7

0.8

0C Control 0C 1-MCP

5C Control 5C 1-MCP

10C Control 10C 1-MCP

A. Chlorophyll

LSD.05

Days

0 5 10 15

Sugar

, mg/

g F

W

3

4

5

6

7

8B. Sugar

LSD.05

Vita

min

C, m

g/10

0g

FW

40

80

120

160

200

240

280

0C Control 0C 1-MCP

5C Control 5C 1-MCP

10C Control 10C 1-MCP

A. Vitamin C (AA + DHA)

LSD.05

Days

0 5 10 15

Glu

cora

phi

nin

, µm

ole

/g D

W

5

6

7

8

9

10

11

12

13

14

15B. Glucoraphinin

LSD.05

Broccoli and Temperature and 1-MCP (no ethylene exposure)

Glucoraphin produces Sulforaphane – potent Phase 2 Enzyme Inducer, inhibit cancer

10°C Air 10°C C2H45°C Air

Feb 2004; 12 days; 8 Feb 2004; 12 days; 8 ppmppm C2H4, Cantwell & KumarC2H4, Cantwell & Kumar

Collards

9

10°C Air 10°C Air + 1-MCP 10°C C2H4 10°C C2H4 + 1-MCP

% Green leaves

0 10 20 30 40 50 60 70 80 90 100

5°C Air

10°C Air

10°C C 2H 4

+ 1-M C P

+ 1-M CP

12days; 8ppm C2H4; 500 ppb 1-M CP

C ollards

12 days; 8 ppm C2H4; 500 ppb 1-MCP

94.7101.7124.2133.2138.5Hue

40.541.220.114.710.1Chroma

40.440.416.610.86.9b*

-3.3-8.3-11.3-10.1-7.8a*

60.460.646.940.241.1L*

12345Color score/

Color values

5 4 3 2 1

KaleColorScore

Cantwell and Fibriyanti, 2007

10

Days

0 2 4 6 8 10 12 14 16 18

Col

or s

core

, 5=

dark

gre

en, 1

=ye

llow

1

2

3

4

5

Mature Kale Leaves 20°C (68°F)15°C (59°F)10°C (50°F) 5°C (41°F)

Days

0 2 4 6 8 10 12 14 16 18

Immature Kale Leaves

LSD.05

Loss of green color by mature and immature Kale leaves stored at 4 temperatures for up to 18 days.

5 4 3 2 1

11

BacteriaBacteriaInjuryInjuryWarm temperaturesWarm temperatures

Cauliflower head and floret discolorationCauliflower head and floret discoloration

14 days air

2.5°C (36°F) 5°C (41°F) 7.5°C (45°F)

12

14 days 5°C (41°F)

1% O2 1% O2 + 7.5% CO21% O2 + 15% CO2

Days

1 2 3 4 5 6

Res

pira

tion

(µ

L C

O2/

g-h)

0

20

40

60

80

100

120

140 0°C (32°F)5°C (41°F)10°C (50°F)

15°C (59°F) 20°C (68°F)

A. Heads

Days

1 2 3 4 5 6

B. Florets

13

Napa or Chinese cabbageNapa or Chinese cabbageBlack Speck DisorderBlack Speck Disorder

Cultivar

1 2 3 4 5 6 7 8 9

Bla

ck s

pec

k in

dex

0

50

100

150

200

250

Air Ethylene

Cv #1= T-740 2= Yuki 3= Spring Flavor 4= Southern King 5= New Summer 6= Chacha 7= China Express 8= Blues 9= WR-70

Black speck development on Napa cabbage stored in air or in ethylene is the same. PAL enzyme levels similar; 1-MCP does not reduce black speck. Cultivars vary greatly in their susceptibility to black speck.

Black speck index = black speck score multiplied by %

extension.

Black Speck Disorder on Chinese CabbageBlack Speck Disorder on Chinese Cabbage

14

Leafy greengrower, SingaporeAug 2007

15

Leafy greengrower, SingaporeAug 2007

2-3°C (34-36°F) best temperature; Asparagus is slightly chill sensitiveCA with high CO2 is beneficial

Asparagus

16

AsparagusAsparagus

M. Cantwell, UC Davis

TTIIPP Cell DivisionCell Enlargement

Sugars LOWProtein & Acidity HIGHSlight Lignification

MIDDLE Cell ElongationHydration

Total Solids 8-14%% Water High

BASE Cell WallThickening

Sugars HIGHProtein & Acidity LOWMaximum Lignification

17

Asparagus packinghouse in Peruhttp://www.freshplaza.com/fotoarchief/apr11.htm

Asparagus storage conditions• 2.5°C (slightly chilling sensitive

• High humidity

• 1-2 weeks; 3 weeks MA

• Modified atmospheres

– O2 5-10%

– CO2 7-10%

Days storage

0 3 6 9 12 15 18 21 24 27 30 33 36

Qua

lity

scor

e

1

2

3

4

5

6

7

8

9

Asparagus: Deterioration and Temperature

Excellent

Good

Fair

Poor2.5°C15°C 10°C 5°C

Tip decay (bacterial)

Frozen and then thawed

18

mg

/100

g fr

esh

we

ight

5

6

7

8

9

10

11

12

mg

/100

g fr

esh

we

ight

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Days 2.5°C (36°F)

0 7 14 21

mg/

g f

resh

wei

ght

6

8

10

12

14

Days 2.5°C (36°F)

0 7 14 21µ

g/g

fres

h w

eig

ht20

40

60

80

100

120

E. Chlorophyll F. Carotenoids

G. Sugars H. Ammonia

UC115

UC157

UC115UC115 compared to UC157. UC157. Asparagus stored at 2.5°C (36°F) up to 21 days.

Data averaged over 2 Tests & 2 Fields, 2004

UC157 UC115

2003 data, UC115 and UC157 averaged

9=e

xce

lle

nt,

1=

un

us

eab

le

6.5

7.0

7.5

8.0

8.5

9.0

LSD.05

After storage

Storage + 2 days 15°C (59°F)

A. Visual Quality

Days storage 2.5°C (36°F)

0 5 10 15 20

1=

no

ne,

5=

sev

ere

1.0

1.5

2.0

2.5

D. Decay cut end

Days storage 2.5°C (36°F)

0 5 10 15 20

1=

no

ne,

5=

sev

ere

1.0

1.5

2.0

2.5

Ne

wto

n-f

orc

e

10

12

14

16 B. Texture

C. Shrivel

Impact of Storage to Simulated Retail Conditions: Transfer from 2.5°C (36°F) to 15°C (59°F)

19

OVERALL CONCLUSION THE SAMEEthylene and 1-MCP treatment do not notably affect spear toughening.

Temperature and delays to cool are Major contributors to spear toughening

For

ce t

o c

ut (

new

tons

fo

rce

)

0

10

20

30

40

50

60

70

80

90

100

110

120

10 13 16 19

LSD.05

0d8d 5°C air8d 10°C air8d 10°C C2H4

8d 10°C 1-MCP + C2H4

Distance from tip (cm)

For

ce t

o c

ut

(new

tons

for

ce)

0

10

20

30

40

50

60

70

80

90

100

110

120

A. Green Butts

B. White Butts

LSD.05

single blade flat 3mm blade to measure force to cut across spear to depth of 5mm at 0.5mm/sec

Celery heartsTrimmed, washed and packagedMobile processing unitChlorine rinseDrain and package in perforated bag

With permission from T&A, June 2007

20

Root diseases affectCelery growth and yield.

If the celery is of marketablequality, root infectionnot affect postharvest qualityor shelf-life

Example of product not marketable

Causes of Quality & Postharvest LossesCauses of Quality & Postharvest Losses

Leafy VegetablesLeafy VegetablesLettucesLettucesSpinachSpinachCabbageCabbageChardChardBroccoliBroccoliCeleryCeleryHerbsHerbsEndivesEndivesAsparagusAsparagusGreen OnionsGreen Onions

Water lossWater loss Mechanical damageMechanical damage Loss of chlorophyll and Loss of chlorophyll and

other nutrientsother nutrients Respiration ratesRespiration rates Microbial growthMicrobial growth Sensitivity to ethyleneSensitivity to ethylene